SQLAlchemy 1.4 Documentation
Changes and Migration
- What’s New in SQLAlchemy 1.4?
- 1.4 Changelog
- 1.3 Changelog¶
- 1.2 Changelog
- 1.1 Changelog
- 1.0 Changelog
- 0.9 Changelog
- 0.8 Changelog
- 0.7 Changelog
- 0.6 Changelog
- 0.5 Changelog
- 0.4 Changelog
- 0.3 Changelog
- 0.2 Changelog
- 0.1 Changelog
- What’s New in SQLAlchemy 1.3?
- What’s New in SQLAlchemy 1.2?
- What’s New in SQLAlchemy 1.1?
- What’s New in SQLAlchemy 1.0?
- What’s New in SQLAlchemy 0.9?
- What’s New in SQLAlchemy 0.8?
- What’s New in SQLAlchemy 0.7?
- What’s New in SQLAlchemy 0.6?
- What’s new in SQLAlchemy 0.5?
- What’s new in SQLAlchemy 0.4?
Project Versions
1.3 Changelog¶
1.3.12¶
no release dateorm¶
[orm] [bug]
Fixed issue involving
¶lazy="raise"
strategy where an ORM delete of an object would raise for a simple “use-get” style many-to-one relationship that had lazy=”raise” configured. This is inconsistent vs. the change introduced in 1.3 as part of #4353, where it was established that a history operation that does not expect emit SQL should bypass thelazy="raise"
check, and instead effectively treat it aslazy="raise_on_sql"
for this case. The fix adjusts the lazy loader strategy to not raise for the case where the lazy load was instructed that it should not emit SQL if the object were not present.References: #4997
[orm] [bug]
Fixed regression introduced in 1.3.0 related to the association proxy refactor in #4351 that prevented
¶composite()
attributes from working in terms of an association proxy that references them.References: #5000
[orm] [bug]
Setting persistence-related flags on
¶relationship()
while also setting viewonly=True will now emit a regular warning, as these flags do not make sense for a viewonly=True relationship. In particular, the “cascade” settings have their own warning that is generated based on the individual values, such as “delete, delete-orphan”, that should not apply to a viewonly relationship. Note however that in the case of “cascade”, these settings are still erroneously taking effect even though the relationship is set up as “viewonly”. In 1.4, all persistence-related cascade settings will be disallowed on a viewonly=True relationship in order to resolve this issue.References: #4993
[orm] [bug] [py3k]
Fixed issue where when assigning a collection to itself as a slice, the mutation operation would fail as it would first erase the assigned collection inadvertently. As an assignment that does not change the contents should not generate events, the operation is now a no-op. Note that the fix only applies to Python 3; in Python 2, the
¶__setitem__
hook isn’t called in this case;__setslice__
is used instead which recreates the list item-by-item in all cases.References: #4990
sql¶
[sql] [bug]
Changed the text of the exception for “Can’t resolve label reference” to include other kinds of label coercions, namely that “DISTINCT” is also in this category under the PostgreSQL dialect.
¶[sql] [bug]
Fixed bug where “distinct” keyword passed to
¶select()
would not treat a string value as a “label reference” in the same way that theselect.distinct()
does; it would instead raise unconditionally. This keyword argument and the others passed toselect()
will ultimately be deprecated for SQLAlchemy 2.0.References: #5028
sqlite¶
[sqlite] [bug]
Fixed issue to workaround SQLite’s behavior of assigning “numeric” affinity to JSON datatypes, first described at Support for SQLite JSON Added, which returns scalar numeric JSON values as a number and not as a string that can be JSON deserialized. The SQLite-specific JSON deserializer now gracefully degrades for this case as an exception and bypasses deserialization for single numeric values, as from a JSON perspective they are already deserialized.
¶References: #5014
mssql¶
[mssql] [bug]
Repaired support for the
¶mssql.DATETIMEOFFSET
datatype on PyODBC, by adding PyODBC-level result handlers as it does not include native support for this datatype. This includes usage of the Python 3 “timezone” tzinfo subclass in order to set up a timezone, which on Python 2 makes use of a minimal backport of “timezone” in sqlalchemy.util.References: #4983
1.3.11¶
Released: November 11, 2019orm¶
[orm] [usecase]
Added accessor
¶Query.is_single_entity()
toQuery
, which will indicate if the results returned by thisQuery
will be a list of ORM entities, or a tuple of entities or column expressions. SQLAlchemy hopes to improve upon the behavior of single entity / tuples in future releases such that the behavior would be explicit up front, however this attribute should be helpful with the current behavior. Pull request courtesy Patrick Hayes.References: #4934
[orm] [bug]
The
¶relationship.omit_join
flag was not intended to be manually set to True, and will now emit a warning when this occurs. The omit_join optimization is detected automatically, and theomit_join
flag was only intended to disable the optimization in the hypothetical case that the optimization may have interfered with correct results, which has not been observed with the modern version of this feature. Setting the flag to True when it is not automatically detected may cause the selectin load feature to not work correctly when a non-default primary join condition is in use.References: #4954
[orm] [bug]
A warning is emitted if a primary key value is passed to
¶Query.get()
that consists of None for all primary key column positions. Previously, passing a single None outside of a tuple would raise aTypeError
and passing a composite None (tuple of None values) would silently pass through. The fix now coerces the single None into a tuple where it is handled consistently with the other None conditions. Thanks to Lev Izraelit for the help with this.References: #4915
[orm] [bug]
The
BakedQuery
will not cache a query that was modified by aQueryEvents.before_compile()
event, so that compilation hooks that may be applying ad-hoc modifications to queries will take effect on each run. In particular this is helpful for events that modify queries used in lazy loading as well as eager loading such as “select in” loading. In order to re-enable caching for a query modified by this event, a new flagbake_ok
is added; see Using the before_compile event for details.A longer term plan to provide a new form of SQL caching should solve this kind of issue more comprehensively.
¶References: #4947
[orm] [bug]
Fixed ORM bug where a “secondary” table that referred to a selectable which in some way would refer to the local primary table would apply aliasing to both sides of the join condition when a relationship-related join, either via
¶Query.join()
or byjoinedload()
, were generated. The “local” side is now excluded.References: #4974
engine¶
[engine] [bug]
Fixed bug where parameter repr as used in logging and error reporting needs additional context in order to distinguish between a list of parameters for a single statement and a list of parameter lists, as the “list of lists” structure could also indicate a single parameter list where the first parameter itself is a list, such as for an array parameter. The engine/connection now passes in an additional boolean indicating how the parameters should be considered. The only SQLAlchemy backend that expects arrays as parameters is that of psycopg2 which uses pyformat parameters, so this issue has not been too apparent, however as other drivers that use positional gain more features it is important that this be supported. It also eliminates the need for the parameter repr function to guess based on the parameter structure passed.
¶References: #4902
[engine] [bug] [postgresql]
Fixed bug in
¶Inspector
where the cache key generation did not take into account arguments passed in the form of tuples, such as the tuple of view name styles to return for the PostgreSQL dialect. This would lead the inspector to cache too generally for a more specific set of criteria. The logic has been adjusted to include every keyword element in the cache, as every argument is expected to be appropriate for a cache else the caching decorator should be bypassed by the dialect.References: #4955
sql¶
[sql] [usecase]
Added new accessors to expressions of type
JSON
to allow for specific datatype access and comparison, covering strings, integers, numeric, boolean elements. This revises the documented approach of CASTing to string when comparing values, instead adding specific functionality into the PostgreSQL, SQlite, MySQL dialects to reliably deliver these basic types in all cases.See also
References: #4276
[sql] [usecase]
The
¶text()
construct now supports “unique” bound parameters, which will dynamically uniquify themselves on compilation thus allowing multipletext()
constructs with the same bound parameter names to be combined together.References: #4933
[sql] [bug] [py3k]
Changed the
¶repr()
of thequoted_name
construct to use regular string repr() under Python 3, rather than running it through “backslashreplace” escaping, which can be misleading.References: #4931
schema¶
[schema] [usecase]
Added DDL support for “computed columns”; these are DDL column specifications for columns that have a server-computed value, either upon SELECT (known as “virtual”) or at the point of which they are INSERTed or UPDATEd (known as “stored”). Support is established for Postgresql, MySQL, Oracle SQL Server and Firebird. Thanks to Federico Caselli for lots of work on this one.
¶References: #4894
[schema] [bug]
Fixed bug where a table that would have a column label overlap with a plain column name, such as “foo.id AS foo_id” vs. “foo.foo_id”, would prematurely generate the
¶._label
attribute for a column before this overlap could be detected due to the use of theindex=True
orunique=True
flag on the column in conjunction with the default naming convention of"column_0_label"
. This would then lead to failures when._label
were used later to generate a bound parameter name, in particular those used by the ORM when generating the WHERE clause for an UPDATE statement. The issue has been fixed by using an alternate._label
accessor for DDL generation that does not affect the state of theColumn
. The accessor also bypasses the key-deduplication step as it is not necessary for DDL, the naming is now consistently"<tablename>_<columnname>"
without any subsequent numeric symbols when used in DDL.References: #4911
mysql¶
mssql¶
[mssql] [bug]
Fixed issue in MSSQL dialect where an expression-based OFFSET value in a SELECT would be rejected, even though the dialect can render this expression inside of a ROW NUMBER-oriented LIMIT/OFFSET construct.
¶References: #4973
[mssql] [bug]
Fixed an issue in the
¶Engine.table_names()
method where it would feed the dialect’s default schema name back into the dialect level table function, which in the case of SQL Server would interpret it as a dot-tokenized schema name as viewed by the mssql dialect, which would cause the method to fail in the case where the database username actually had a dot inside of it. In 1.3, this method is still used by theMetaData.reflect()
function so is a prominent codepath. In 1.4, which is the current master development branch, this issue doesn’t exist, both becauseMetaData.reflect()
isn’t using this method nor does the method pass the default schema name explicitly. The fix nonetheless guards against the default server name value returned by the dialect from being interpreted as dot-tokenized name under any circumstances by wrapping it in quoted_name().References: #4923
oracle¶
[oracle] [usecase]
Added dialect-level flag
¶encoding_errors
to the cx_Oracle dialect, which can be specified as part ofcreate_engine()
. This is passed to SQLAlchemy’s unicode decoding converter under Python 2, and to cx_Oracle’scursor.var()
object as theencodingErrors
parameter under Python 3, for the very unusual case that broken encodings are present in the target database which cannot be fetched unless error handling is relaxed. The value is ultimately one of the Python “encoding errors” parameters passed todecode()
.References: #4799
[oracle] [bug] [firebird]
Modified the approach of “name normalization” for the Oracle and Firebird dialects, which converts from the UPPERCASE-as-case-insensitive convention of these dialects into lowercase-as-case-insensitive for SQLAlchemy, to not automatically apply the
¶quoted_name
construct to a name that matches itself under upper or lower case conversion, as is the case for many non-european characters. All names used within metadata structures are converted toquoted_name
objects in any case; the change here would only affect the output of some inspection functions.References: #4931
[oracle] [bug]
The
¶sqltypes.NCHAR
datatype will now bind to thecx_Oracle.FIXED_NCHAR
DBAPI data bindings when used in a bound parameter, which supplies proper comparison behavior against a variable-length string. Previously, thesqltypes.NCHAR
datatype would bind tocx_oracle.NCHAR
which is not fixed length; thesqltypes.CHAR
datatype already binds tocx_Oracle.FIXED_CHAR
so it is now consistent thatsqltypes.NCHAR
binds tocx_Oracle.FIXED_NCHAR
.References: #4913
firebird¶
misc¶
[bug] [tests]
Fixed test failures which would occur with newer SQLite as of version 3.30 or greater, due to their addition of nulls ordering syntax as well as new restrictions on aggregate functions. Pull request courtesy Nils Philippsen.
¶References: #4920
[bug] [installation] [windows]
Added a workaround for a setuptools-related failure that has been observed as occurring on Windows installations, where setuptools is not correctly reporting a build error when the MSVC build dependencies are not installed and therefore not allowing graceful degradation into non C extensions builds.
¶References: #4967
1.3.10¶
Released: October 9, 2019mssql¶
oracle¶
[oracle] [bug]
Fixed regression in Oracle dialect that was inadvertently using max identifier length of 128 characters on Oracle server 12.2 and greater even though the stated contract for the remainder of the 1.3 series is that this value stays at 30 until version SQLAlchemy 1.4. Also repaired issues with the retrieval of the “compatibility” version, and removed the warning emitted when the “v$parameter” view was not accessible as this was causing user confusion.
¶
1.3.9¶
Released: October 4, 2019orm¶
[orm] [bug]
Fixed regression in selectinload loader strategy caused by #4775 (released in version 1.3.6) where a many-to-one attribute of None would no longer be populated by the loader. While this was usually not noticeable due to the lazyloader populating None upon get, it would lead to a detached instance error if the object were detached.
¶References: #4872
[orm] [bug]
Passing a plain string expression to
¶Session.query()
is deprecated, as all string coercions were removed in #4481 and this one should have been included. Theliteral_column()
function may be used to produce a textual column expression.References: #4873
[orm] [bug]
A warning is emitted for a condition in which the
¶Session
may implicitly swap an object out of the identity map for another one with the same primary key, detaching the old one, which can be an observed result of load operations which occur within theSessionEvents.after_flush()
hook. The warning is intended to notify the user that some special condition has caused this to happen and that the previous object may not be in the expected state.References: #4890
engine¶
[engine] [usecase]
Added new
create_engine()
parametercreate_engine.max_identifier_length
. This overrides the dialect-coded “max identifier length” in order to accommodate for databases that have recently changed this length and the SQLAlchemy dialect has not yet been adjusted to detect for that version. This parameter interacts with the existingcreate_engine.label_length
parameter in that it establishes the maximum (and default) value for anonymously generated labels. Additionally, post-connection detection of max identifier lengths has been added to the dialect system. This feature is first being used by the Oracle dialect.See also
Max Identifier Lengths - in the Oracle dialect documentation
References: #4857
sql¶
[sql] [usecase]
Added an explicit error message for the case when objects passed to
¶Table
are notSchemaItem
objects, rather than resolving to an attribute error.References: #4847
[sql] [bug]
Characters that interfere with “pyformat” or “named” formats in bound parameters, namely
¶%, (, )
and the space character, as well as a few other typically undesirable characters, are stripped early for abindparam()
that is using an anonymized name, which is typically generated automatically from a named column which itself includes these characters in its name and does not use a.key
, so that they do not interfere either with the SQLAlchemy compiler’s use of string formatting or with the driver-level parsing of the parameter, both of which could be demonstrated before the fix. The change only applies to anonymized parameter names that are generated and consumed internally, not end-user defined names, so the change should have no impact on any existing code. Applies in particular to the psycopg2 driver which does not otherwise quote special parameter names, but also strips leading underscores to suit Oracle (but not yet leading numbers, as some anon parameters are currently entirely numeric/underscore based); Oracle in any case continues to quote parameter names that include special characters.References: #4837
sqlite¶
mssql¶
[mssql] [bug]
Added identifier quoting to the schema name applied to the “use” statement which is invoked when a SQL Server multipart schema name is used within a
¶Table
that is being reflected, as well as forInspector
methods such asInspector.get_table_names()
; this accommodates for special characters or spaces in the database name. Additionally, the “use” statement is not emitted if the current database matches the target owner database name being passed.References: #4883
oracle¶
[oracle] [usecase]
The Oracle dialect now emits a warning if Oracle version 12.2 or greater is used, and the
create_engine.max_identifier_length
parameter is not set. The version in this specific case defaults to that of the “compatibility” version set in the Oracle server configuration, not the actual server version. In version 1.4, the default max_identifier_length for 12.2 or greater will move to 128 characters. In order to maintain forwards compatibility, applications should setcreate_engine.max_identifier_length
to 30 in order to maintain the same length behavior, or to 128 in order to test the upcoming behavior. This length determines among other things how generated constraint names are truncated for statements likeCREATE CONSTRAINT
andDROP CONSTRAINT
, which means a the new length may produce a name-mismatch against a name that was generated with the old length, impacting database migrations.See also
Max Identifier Lengths - in the Oracle dialect documentation
References: #4857
[oracle] [bug]
Restored adding cx_Oracle.DATETIME to the setinputsizes() call when a SQLAlchemy
¶Date
,DateTime
orTime
datatype is used, as some complex queries require this to be present. This was removed in the 1.2 series for arbitrary reasons.References: #4886
misc¶
[bug] [tests]
Fixed unit test regression released in 1.3.8 that would cause failure for Oracle, SQL Server and other non-native ENUM platforms due to new enumeration tests added as part of #4285 enum sortability in the unit of work; the enumerations created constraints that were duplicated on name.
¶References: #4285
1.3.8¶
Released: August 27, 2019orm¶
[orm] [usecase]
Added support for the use of an
¶Enum
datatype using Python pep-435 enumeration objects as values for use as a primary key column mapped by the ORM. As these values are not inherently sortable, as required by the ORM for primary keys, a newTypeEngine.sort_key_function
attribute is added to the typing system which allows any SQL type to implement a sorting for Python objects of its type which is consulted by the unit of work. TheEnum
type then defines this using the database value of a given enumeration. The sorting scheme can be also be redefined by passing a callable to theEnum.sort_key_function
parameter. Pull request courtesy Nicolas Caniart.References: #4285
[orm] [bug]
Fixed bug where
¶Load
objects were not pickleable due to mapper/relationship state in the internal context dictionary. These objects are now converted to picklable using similar techniques as that of other elements within the loader option system that have long been serializable.References: #4823
engine¶
[engine] [feature]
Added new parameter
¶create_engine.hide_parameters
which when set to True will cause SQL parameters to no longer be logged, nor rendered in the string representation of aStatementError
object.References: #4815
[engine] [bug]
Fixed an issue whereby if the dialect “initialize” process which occurs on first connect would encounter an unexpected exception, the initialize process would fail to complete and then no longer attempt on subsequent connection attempts, leaving the dialect in an un-initialized, or partially initialized state, within the scope of parameters that need to be established based on inspection of a live connection. The “invoke once” logic in the event system has been reworked to accommodate for this occurrence using new, private API features that establish an “exec once” hook that will continue to allow the initializer to fire off on subsequent connections, until it completes without raising an exception. This does not impact the behavior of the existing
¶once=True
flag within the event system.References: #4807
postgresql¶
[postgresql] [usecase]
Added support for reflection of CHECK constraints that include the special PostgreSQL qualifier “NOT VALID”, which can be present for CHECK constraints that were added to an exsiting table with the directive that they not be applied to existing data in the table. The PostgreSQL dictionary for CHECK constraints as returned by
¶Inspector.get_check_constraints()
may include an additional entrydialect_options
which within will contain an entry"not_valid": True
if this symbol is detected. Pull request courtesy Bill Finn.References: #4824
[postgresql] [bug]
Revised the approach for the just added support for the psycopg2 “execute_values()” feature added in 1.3.7 for #4623. The approach relied upon a regular expression that would fail to match for a more complex INSERT statement such as one which had subqueries involved. The new approach matches exactly the string that was rendered as the VALUES clause.
¶References: #4623
[postgresql] [bug]
Fixed bug where Postgresql operators such as
¶postgresql.ARRAY.Comparator.contains()
andpostgresql.ARRAY.Comparator.contained_by()
would fail to function correctly for non-integer values when used against apostgresql.array
object, due to an erroneous assert statement.References: #4822
sqlite¶
[sqlite] [bug] [reflection]
Fixed bug where a FOREIGN KEY that was set up to refer to the parent table by table name only without the column names would not correctly be reflected as far as setting up the “referred columns”, since SQLite’s PRAGMA does not report on these columns if they weren’t given explicitly. For some reason this was harcoded to assume the name of the local column, which might work for some cases but is not correct. The new approach reflects the primary key of the referred table and uses the constraint columns list as the referred columns list, if the remote column(s) aren’t present in the reflected pragma directly.
¶References: #4810
1.3.7¶
Released: August 14, 2019orm¶
[orm] [bug]
Fixed regression caused by new selectinload for many-to-one logic where a primaryjoin condition not based on real foreign keys would cause KeyError if a related object did not exist for a given key value on the parent object.
¶References: #4777
[orm] [bug]
Fixed bug where using
¶Query.first()
or a slice expression in conjunction with a query that has an expression based “offset” applied would raise TypeError, due to an “or” conditional against “offset” that did not expect it to be a SQL expression as opposed to an integer or None.References: #4803
sql¶
[sql] [bug]
Fixed issue where
¶Index
object which contained a mixture of functional expressions which were not resolvable to a particular column, in combination with string-based column names, would fail to initialize its internal state correctly leading to failures during DDL compilation.References: #4778
[sql] [bug]
Fixed bug where
¶TypeEngine.column_expression()
method would not be applied to subsequent SELECT statements inside of a UNION or otherCompoundSelect
, even though the SELECT statements are rendered at the topmost level of the statement. New logic now differentiates between rendering the column expression, which is needed for all SELECTs in the list, vs. gathering the returned data type for the result row, which is needed only for the first SELECT.References: #4787
[sql] [bug]
Fixed issue where internal cloning of SELECT constructs could lead to a key error if the copy of the SELECT changed its state such that its list of columns changed. This was observed to be occurring in some ORM scenarios which may be unique to 1.3 and above, so is partially a regression fix.
¶References: #4780
postgresql¶
[postgresql] [usecase]
Added new dialect flag for the psycopg2 dialect,
executemany_mode
which supersedes the previous experimentaluse_batch_mode
flag.executemany_mode
supports both the “execute batch” and “execute values” functions provided by psycopg2, the latter which is used for compiledinsert()
constructs. Pull request courtesy Yuval Dinari.See also
References: #4623
mysql¶
[mysql] [usecase]
Added reserved words ARRAY and MEMBER to the MySQL reserved words list, as MySQL 8.0 has now made these reserved.
¶References: #4783
[mysql] [bug]
The MySQL dialects will emit “SET NAMES” at the start of a connection when charset is given to the MySQL driver, to appease an apparent behavior observed in MySQL 8.0 that raises a collation error when a UNION includes string columns unioned against columns of the form CAST(NULL AS CHAR(..)), which is what SQLAlchemy’s polymorphic_union function does. The issue seems to have affected PyMySQL for at least a year, however has recently appeared as of mysqlclient 1.4.4 based on changes in how this DBAPI creates a connection. As the presence of this directive impacts three separate MySQL charset settings which each have intricate effects based on their presense, SQLAlchemy will now emit the directive on new connections to ensure correct behavior.
¶References: #4804
[mysql] [bug]
Added another fix for an upstream MySQL 8 issue where a case sensitive table name is reported incorrectly in foreign key constraint reflection, this is an extension of the fix first added for #4344 which affects a case sensitive column name. The new issue occurs through MySQL 8.0.17, so the general logic of the 88718 fix remains in place.
See also
https://bugs.mysql.com/bug.php?id=96365 - upstream bug
References: #4751
sqlite¶
[sqlite] [bug]
The dialects that support json are supposed to take arguments
¶json_serializer
andjson_deserializer
at the create_engine() level, however the SQLite dialect calls them_json_serilizer
and_json_deserilalizer
. The names have been corrected, the old names are accepted with a change warning, and these parameters are now documented ascreate_engine.json_serializer
andcreate_engine.json_deserializer
.References: #4798
[sqlite] [bug]
Fixed bug where usage of “PRAGMA table_info” in SQLite dialect meant that reflection features to detect for table existence, list of table columns, and list of foreign keys, would default to any table in any attached database, when no schema name was given and the table did not exist in the base schema. The fix explicitly runs PRAGMA for the ‘main’ schema and then the ‘temp’ schema if the ‘main’ returned no rows, to maintain the behavior of tables + temp tables in the “no schema” namespace, attached tables only in the “schema” namespace.
¶References: #4793
mssql¶
[mssql] [usecase]
Added new
¶mssql.try_cast()
construct for SQL Server which emits “TRY_CAST” syntax. Pull request courtesy Leonel Atencio.References: #4782
misc¶
[bug] [events]
Fixed issue in event system where using the
¶once=True
flag with dynamically generated listener functions would cause event registration of future events to fail if those listener functions were garbage collected after they were used, due to an assumption that a listened function is strongly referenced. The “once” wrapped is now modified to strongly reference the inner function persistently, and documentation is updated that using “once” does not imply automatic de-registration of listener functions.References: #4794
1.3.6¶
Released: July 21, 2019orm¶
[orm] [feature]
Added new loader option method
¶Load.options()
which allows loader options to be constructed hierarchically, so that many sub-options can be applied to a particular path without needing to calldefaultload()
many times. Thanks to Alessio Bogon for the idea.References: #4736
[orm] [bug]
Fixed regression caused by #4365 where a join from an entity to itself without using aliases no longer raises an informative error message, instead failing on an assertion. The informative error condition has been restored.
¶References: #4773
[orm] [bug]
Fixed an issue where the
¶orm._ORMJoin.join()
method, which is a not-internally-used ORM-level method that exposes what is normally an internal process ofQuery.join()
, did not propagate thefull
andouterjoin
keyword arguments correctly. Pull request courtesy Denis Kataev.References: #4713
[orm] [bug]
Fixed bug where a many-to-one relationship that specified
¶uselist=True
would fail to update correctly during a primary key change where a related column needs to change.References: #4772
[orm] [bug]
Fixed bug where the detection for many-to-one or one-to-one use with a “dynamic” relationship, which is an invalid configuration, would fail to raise if the relationship were configured with
¶uselist=True
. The current fix is that it warns, instead of raises, as this would otherwise be backwards incompatible, however in a future release it will be a raise.References: #4772
[orm] [bug]
Fixed bug where a synonym created against a mapped attribute that does not exist yet, as is the case when it refers to backref before mappers are configured, would raise recursion errors when trying to test for attributes on it which ultimately don’t exist (as occurs when the classes are run through Sphinx autodoc), as the unconfigured state of the synonym would put it into an attribute not found loop.
¶References: #4767
[orm] [performance]
The optimization applied to selectin loading in #4340 where a JOIN is not needed to eagerly load related items is now applied to many-to-one relationships as well, so that only the related table is queried for a simple join condition. In this case, the related items are queried based on the value of a foreign key column on the parent; if these columns are deferred or otherwise not loaded on any of the parent objects in the collection, the loader falls back to the JOIN method.
¶References: #4775
engine¶
[engine] [bug]
Fixed bug where using reflection function such as
¶MetaData.reflect()
with anEngine
object that had execution options applied to it would fail, as the resultingOptionEngine
proxy object failed to include a.engine
attribute used within the reflection routines.References: #4754
sql¶
[sql] [bug]
Adjusted the initialization for
¶Enum
to minimize how often it invokes the.__members__
attribute of a given PEP-435 enumeration object, to suit the case where this attribute is expensive to invoke, as is the case for some popular third party enumeration libraries.References: #4758
[sql] [bug] [postgresql]
Fixed issue where the
¶array_agg
construct in combination withFunctionElement.filter()
would not produce the correct operator precedence in combination with the array index operator.References: #4760
[sql] [bug]
Fixed an unlikely issue where the “corresponding column” routine for unions and other
¶CompoundSelect
objects could return the wrong column in some overlapping column situtations, thus potentially impacting some ORM operations when set operations are in use, if the underlyingselect()
constructs were used previously in other similar kinds of routines, due to a cached value not being cleared.References: #4747
postgresql¶
[postgresql] [usecase]
Added support for reflection of indexes on PostgreSQL partitioned tables, which was added to PostgreSQL as of version 11.
¶References: #4771
[postgresql] [usecase]
Added support for multidimensional Postgresql array literals via nesting the
postgresql.array
object within another one. The multidimensional array type is detected automatically.See also
References: #4756
mysql¶
[mysql] [bug]
Fixed bug where the special logic to render “NULL” for the
¶TIMESTAMP
datatype whennullable=True
would not work if the column’s datatype were aTypeDecorator
or aVariant
. The logic now ensures that it unwraps down to the originalTIMESTAMP
so that this special case NULL keyword is correctly rendered when requested.References: #4743
[mysql] [bug]
Enhanced MySQL/MariaDB version string parsing to accommodate for exotic MariaDB version strings where the “MariaDB” word is embedded among other alphanumeric characters such as “MariaDBV1”. This detection is critical in order to correctly accommodate for API features that have split between MySQL and MariaDB such as the “transaction_isolation” system variable.
¶References: #4624
sqlite¶
[sqlite] [usecase]
Added support for composite (tuple) IN operators with SQLite, by rendering the VALUES keyword for this backend. As other backends such as DB2 are known to use the same syntax, the syntax is enabled in the base compiler using a dialect-level flag
¶tuple_in_values
. The change also includes support for “empty IN tuple” expressions for SQLite when using “in_()” between a tuple value and an empty set.References: #4766
mssql¶
[mssql] [bug]
Ensured that the queries used to reflect indexes and view definitions will explicitly CAST string parameters into NVARCHAR, as many SQL Server drivers frequently treat string values, particularly those with non-ascii characters or larger string values, as TEXT which often don’t compare correctly against VARCHAR characters in SQL Server’s information schema tables for some reason. These CAST operations already take place for reflection queries against SQL Server
¶information_schema.
tables but were missing from three additional queries that are againstsys.
tables.References: #4745
1.3.5¶
Released: June 17, 2019orm¶
[orm] [bug]
Fixed a series of related bugs regarding joined table inheritance more than two levels deep, in conjunction with modification to primary key values, where those primary key columns are also linked together in a foreign key relationship as is typical for joined table inheritance. The intermediary table in a three-level inheritance hierarchy will now get its UPDATE if only the primary key value has changed and passive_updates=False (e.g. foreign key constraints not being enforced), whereas before it would be skipped; similarly, with passive_updates=True (e.g. ON UPDATE CASCADE in effect), the third-level table will not receive an UPDATE statement as was the case earlier which would fail since CASCADE already modified it. In a related issue, a relationship linked to a three-level inheritance hierarchy on the primary key of an intermediary table of a joined-inheritance hierarchy will also correctly have its foreign key column updated when the parent object’s primary key is modified, even if that parent object is a subclass of the linked parent class, whereas before these classes would not be counted.
¶References: #4723
[orm] [bug]
Fixed bug where the
¶Mapper.all_orm_descriptors
accessor would return an entry for theMapper
itself under the declarative__mapper___
key, when this is not a descriptor. The.is_attribute
flag that’s present on allInspectionAttr
objects is now consulted, which has also been modified to beTrue
for an association proxy, as it was erroneously set to False for this object.References: #4729
[orm] [bug]
Fixed regression in
¶Query.join()
where thealiased=True
flag would not properly apply clause adaptation to filter criteria, if a previous join were made to the same entity. This is because the adapters were placed in the wrong order. The order has been reversed so that the adapter for the most recentaliased=True
call takes precedence as was the case in 1.2 and earlier. This broke the “elementtree” examples among other things.References: #4704
[orm] [bug] [py3k]
Replaced the Python compatbility routines for
¶getfullargspec()
with a fully vendored version from Python 3.3. Originally, Python was emitting deprecation warnings for this function in Python 3.8 alphas. While this change was reverted, it was observed that Python 3 implementations forgetfullargspec()
are an order of magnitude slower as of the 3.4 series where it was rewritten againstSignature
. While Python plans to improve upon this situation, SQLAlchemy projects for now are using a simple replacement to avoid any future issues.References: #4674
[orm] [bug]
Reworked the attribute mechanics used by
¶AliasedClass
to no longer rely upon calling__getattribute__
on the MRO of the wrapped class, and to instead resolve the attribute normally on the wrapped class using getattr(), and then unwrap/adapt that. This allows a greater range of attribute styles on the mapped class including special__getattr__()
schemes; but it also makes the code simpler and more resilient in general.References: #4694
sql¶
[sql] [bug]
Fixed a series of quoting issues which all stemmed from the concept of the
¶literal_column()
construct, which when being “proxied” through a subquery to be referred towards by a label that matches its text, the label would not have quoting rules applied to it, even if the string in theLabel
were set up as aquoted_name
construct. Not applying quoting to the text of theLabel
is a bug because this text is strictly a SQL identifier name and not a SQL expression, and the string should not have quotes embedded into it already unlike theliteral_column()
which it may be applied towards. The existing behavior of a non-labeledliteral_column()
being propagated as is on the outside of a subquery is maintained in order to help with manual quoting schemes, although it’s not clear if valid SQL can be generated for such a construct in any case.References: #4730
postgresql¶
[postgresql] [usecase]
Added support for column sorting flags when reflecting indexes for PostgreSQL, including ASC, DESC, NULLSFIRST, NULLSLAST. Also adds this facility to the reflection system in general which can be applied to other dialects in future releases. Pull request courtesy Eli Collins.
¶References: #4717
[postgresql] [bug]
Fixed bug where PostgreSQL dialect could not correctly reflect an ENUM datatype that has no members, returning a list with
¶None
for theget_enums()
call and raising a TypeError when reflecting a column which has such a datatype. The inspection now returns an empty list.References: #4701
1.3.4¶
Released: May 27, 2019orm¶
[orm] [bug]
Fixed issue where the
¶AttributeEvents.active_history
flag would not be set for an event listener that propgated to a subclass via theAttributeEvents.propagate
flag. This bug has been present for the full span of theAttributeEvents
system.References: #4695
[orm] [bug]
Fixed regression where new association proxy system was still not proxying hybrid attributes when they made use of the
¶@hybrid_property.expression
decorator to return an alternate SQL expression, or when the hybrid returned an arbitraryPropComparator
, at the expression level. This involved further generalization of the heuristics used to detect the type of object being proxied at the level ofQueryableAttribute
, to better detect if the descriptor ultimately serves mapped classes or column expressions.References: #4690
[orm] [bug]
Applied the mapper “configure mutex” against the declarative class mapping process, to guard against the race which can occur if mappers are used while dynamic module import schemes are still in the process of configuring mappers for related classes. This does not guard against all possible race conditions, such as if the concurrent import has not yet encountered the dependent classes as of yet, however it guards against as much as possible within the SQLAlchemy declarative process.
¶References: #4686
[orm] [bug]
A warning is now emitted for the case where a transient object is being merged into the session with
¶Session.merge()
when that object is already transient in theSession
. This warns for the case where the object would normally be double-inserted.References: #4647
[orm] [bug]
Fixed regression in new relationship m2o comparison logic first introduced at Improvement to the behavior of many-to-one query expressions when comparing to an attribute that is persisted as NULL and is in an un-fetched state in the mapped instance. Since the attribute has no explicit default, it needs to default to NULL when accessed in a persistent setting.
¶References: #4676
engine¶
[engine] [bug] [postgresql]
Moved the “rollback” which occurs during dialect initialization so that it occurs after additional dialect-specific initialize steps, in particular those of the psycopg2 dialect which would inadvertently leave transactional state on the first new connection, which could interfere with some psycopg2-specific APIs which require that no transaction is started. Pull request courtesy Matthew Wilkes.
¶References: #4663
sql¶
[sql] [bug]
Fixed that the
¶GenericFunction
class was inadvertently registering itself as one of the named functions. Pull request courtesy Adrien Berchet.References: #4653
[sql] [bug]
Fixed issue where double negation of a boolean column wouldn’t reset the “NOT” operator.
¶References: #4618
[sql] [bug]
The
¶GenericFunction
namespace is being migrated so that function names are looked up in a case-insensitive manner, as SQL functions do not collide on case sensitive differences nor is this something which would occur with user-defined functions or stored procedures. Lookups for functions declared withGenericFunction
now use a case insensitive scheme, however a deprecation case is supported which allows two or moreGenericFunction
objects with the same name of different cases to exist, which will cause case sensitive lookups to occur for that particular name, while emitting a warning at function registration time. Thanks to Adrien Berchet for a lot of work on this complicated feature.References: #4569
postgresql¶
mysql¶
[mysql] [bug]
Added support for DROP CHECK constraint which is required by MySQL 8.0.16 to drop a CHECK constraint; MariaDB supports plain DROP CONSTRAINT. The logic distinguishes between the two syntaxes by checking the server version string for MariaDB presence. Alembic migrations has already worked around this issue by implementing its own DROP for MySQL / MariaDB CHECK constraints, however this change implements it straight in Core so that its available for general use. Pull request courtesy Hannes Hansen.
¶References: #4650
mssql¶
[mssql] [feature]
Added support for SQL Server filtered indexes, via the
mssql_where
parameter which works similarly to that of thepostgresql_where
index function in the PostgreSQL dialect.See also
References: #4657
[mssql] [bug]
Added error code 20047 to “is_disconnect” for pymssql. Pull request courtesy Jon Schuff.
¶References: #4680
1.3.3¶
Released: April 15, 2019orm¶
[orm] [bug]
Fixed 1.3 regression in new “ambiguous FROMs” query logic introduced in Query.join() handles ambiguity in deciding the “left” side more explicitly where a
¶Query
that explicitly places an entity in the FROM clause withQuery.select_from()
and also joins to it usingQuery.join()
would later cause an “ambiguous FROM” error if that entity were used in additional joins, as the entity appears twice in the “from” list of theQuery
. The fix resolves this ambiguity by folding the standalone entity into the join that it’s already a part of in the same way that ultimately happens when the SELECT statement is rendered.References: #4584
[orm] [bug]
Adjusted the
¶Query.filter_by()
method to not calland()
internally against multiple criteria, instead passing it off toQuery.filter()
as a series of criteria, instead of a single criteria. This allowsQuery.filter_by()
to defer toQuery.filter()
’s treatment of variable numbers of clauses, including the case where the list is empty. In this case, theQuery
object will not have a.whereclause
, which allows subsequent “no whereclause” methods likeQuery.select_from()
to behave consistently.References: #4606
postgresql¶
[postgresql] [bug]
Fixed regression from release 1.3.2 caused by #4562 where a URL that contained only a query string and no hostname, such as for the purposes of specifying a service file with connection information, would no longer be propagated to psycopg2 properly. The change in #4562 has been adjusted to further suit psycopg2’s exact requirements, which is that if there are any connection parameters whatsoever, the “dsn” parameter is no longer required, so in this case the query string parameters are passed alone.
¶References: #4601
mssql¶
[mssql] [bug]
Fixed issue in SQL Server dialect where if a bound parameter were present in an ORDER BY expression that would ultimately not be rendered in the SQL Server version of the statement, the parameters would still be part of the execution parameters, leading to DBAPI-level errors. Pull request courtesy Matt Lewellyn.
¶References: #4587
misc¶
[bug] [pool]
Fixed behavioral regression as a result of deprecating the “use_threadlocal” flag for
¶Pool
, where theSingletonThreadPool
no longer makes use of this option which causes the “rollback on return” logic to take place when the sameEngine
is used multiple times in the context of a transaction to connect or implicitly execute, thereby cancelling the transaction. While this is not the recommended way to work with engines and connections, it is nonetheless a confusing behavioral change as when usingSingletonThreadPool
, the transaction should stay open regardless of what else is done with the same engine in the same thread. Theuse_threadlocal
flag remains deprecated however theSingletonThreadPool
now implements its own version of the same logic.References: #4585
[bug] [ext]
Fixed bug where using
¶copy.copy()
orcopy.deepcopy()
onMutableList
would cause the items within the list to be duplicated, due to an inconsistency in how Python pickle and copy both make use of__getstate__()
and__setstate__()
regarding lists. In order to resolve, a__reduce_ex__
method had to be added toMutableList
. In order to maintain backwards compatibility with existing pickles based on__getstate__()
, the__setstate__()
method remains as well; the test suite asserts that pickles made against the old version of the class can still be deserialized by the pickle module.References: #4603
1.3.2¶
Released: April 2, 2019orm¶
[orm] [bug] [ext]
Restored instance-level support for plain Python descriptors, e.g.
¶@property
objects, in conjunction with association proxies, in that if the proxied object is not within ORM scope at all, it gets classified as “ambiguous” but is proxed directly. For class level access, a basic class level``__get__()`` now returns theAmbiguousAssociationProxyInstance
directly, rather than raising its exception, which is the closest approximation to the previous behavior that returned theAssociationProxy
itself that’s possible. Also improved the stringification of these objects to be more descriptive of current state.[orm] [bug]
Fixed bug where use of
¶with_polymorphic()
or other aliased construct would not properly adapt when the aliased target were used as theSelect.correlate_except()
target of a subquery used inside of acolumn_property()
. This required a fix to the clause adaption mechanics to properly handle a selectable that shows up in the “correlate except” list, in a similar manner as which occurs for selectables that show up in the “correlate” list. This is ultimately a fairly fundamental bug that has lasted for a long time but it is hard to come across it.References: #4537
[orm] [bug]
Fixed regression where a new error message that was supposed to raise when attempting to link a relationship option to an AliasedClass without using
¶PropComparator.of_type()
would instead raise anAttributeError
. Note that in 1.3, it is no longer valid to create an option path from a plain mapper relationship to anAliasedClass
without usingPropComparator.of_type()
.References: #4566
sql¶
[sql] [bug] [documentation]
Thanks to TypeEngine methods bind_expression, column_expression work with Variant, type-specific types, we no longer need to rely on recipes that subclass dialect-specific types directly,
¶TypeDecorator
can now handle all cases. Additionally, the above change made it slightly less likely that a direct subclass of a base SQLAlchemy type would work as expected, which could be misleading. Documentation has been updated to useTypeDecorator
for these examples including the PostgreSQL “ArrayOfEnum” example datatype and direct support for the “subclass a type directly” has been removed.References: #4580
postgresql¶
[postgresql] [feature]
Added support for parameter-less connection URLs for the psycopg2 dialect, meaning, the URL can be passed to
¶create_engine()
as"postgresql+psycopg2://"
with no additional arguments to indicate an empty DSN passed to libpq, which indicates to connect to “localhost” with no username, password, or database given. Pull request courtesy Julian Mehnle.References: #4562
[postgresql] [bug]
Modified the
¶Select.with_for_update.of
parameter so that if a join or other composed selectable is passed, the individualTable
objects will be filtered from it, allowing one to pass a join() object to the parameter, as occurs normally when using joined table inheritance with the ORM. Pull request courtesy Raymond Lu.References: #4550
1.3.1¶
Released: March 9, 2019orm¶
mssql¶
[mssql] [bug]
A commit() is emitted after an isolation level change to SNAPSHOT, as both pyodbc and pymssql open an implicit transaction which blocks subsequent SQL from being emitted in the current transaction.
¶This change is also backported to: 1.2.19
References: #4536
[mssql] [bug]
Fixed regression in SQL Server reflection due to #4393 where the removal of open-ended
¶**kw
from theFloat
datatype caused reflection of this type to fail due to a “scale” argument being passed.References: #4525
1.3.0¶
Released: March 4, 2019orm¶
[orm] [feature]
The
¶Query.get()
method can now accept a dictionary of attribute keys and values as a means of indicating the primary key value to load; is particularly useful for composite primary keys. Pull request courtesy Sanjana S.References: #4316
[orm] [feature]
A SQL expression can now be assigned to a primary key attribute for an ORM flush in the same manner as ordinary attributes as described in Embedding SQL Insert/Update Expressions into a Flush where the expression will be evaulated and then returned to the ORM using RETURNING, or in the case of pysqlite, works using the cursor.lastrowid attribute.Requires either a database that supports RETURNING (e.g. Postgresql, Oracle, SQL Server) or pysqlite.
¶References: #3133
engine¶
[engine] [feature]
Revised the formatting for
¶StatementError
when stringified. Each error detail is broken up over multiple newlines instead of spaced out on a single line. Additionally, the SQL representation now stringifies the SQL statement rather than usingrepr()
, so that newlines are rendered as is. Pull request courtesy Nate Clark.References: #4500
sql¶
[sql] [bug]
The
¶Alias
class and related subclassesCTE
,Lateral
andTableSample
have been reworked so that it is not possible for a user to construct the objects directly. These constructs require that the standalone construction function or selectable-bound method be used to instantiate new objects.References: #4509
schema¶
[schema] [feature]
Added new parameters
¶Table.resolve_fks
andMetaData.reflect.resolve_fks
which when set to False will disable the automatic reflection of related tables encountered inForeignKey
objects, which can both reduce SQL overhead for omitted tables as well as avoid tables that can’t be reflected for database-specific reasons. TwoTable
objects present in the sameMetaData
collection can still refer to each other even if the reflection of the two tables occurred separately.References: #4517
1.3.0b3¶
Released: February 8, 2019orm¶
[orm] [bug]
Improved the behavior of
¶orm.with_polymorphic()
in conjunction with loader options, in particular wildcard operations as well asorm.load_only()
. The polymorphic object will be more accurately targeted so that column-level options on the entity will correctly take effect.The issue is a continuation of the same kinds of things fixed in #4468.References: #4469
orm declarative¶
[bug] [declarative] [orm]
Added some helper exceptions that invoke when a mapping based on
¶AbstractConcreteBase
,DeferredReflection
, orAutoMap
is used before the mapping is ready to be used, which contain descriptive information on the class, rather than falling through into other failure modes that are less informative.References: #4470
sql¶
[sql] [bug]
Fully removed the behavior of strings passed directly as components of a
select()
orQuery
object being coerced totext()
constructs automatically; the warning that has been emitted is now an ArgumentError or in the case of order_by() / group_by() a CompileError. This has emitted a warning since version 1.0 however its presence continues to create concerns for the potential of mis-use of this behavior.Note that public CVEs have been posted for order_by() / group_by() which are resolved by this commit: CVE-2019-7164 CVE-2019-7548
¶References: #4481
[sql] [bug]
Quoting is applied to
¶Function
names, those which are usually but not necessarily generated from thesql.func
construct, at compile time if they contain illegal characters, such as spaces or punctuation. The names are as before treated as case insensitive however, meaning if the names contain uppercase or mixed case characters, that alone does not trigger quoting. The case insensitivity is currently maintained for backwards compatibility.References: #4467
[sql] [bug]
Added “SQL phrase validation” to key DDL phrases that are accepted as plain strings, including
¶ForeignKeyConstraint.on_delete
,ForeignKeyConstraint.on_update
,ExcludeConstraint.using
,ForeignKeyConstraint.initially
, for areas where a series of SQL keywords only are expected.Any non-space characters that suggest the phrase would need to be quoted will raise aCompileError
. This change is related to the series of changes committed as part of #4481.References: #4481
postgresql¶
[postgresql] [bug]
Fixed issue where using an uppercase name for an index type (e.g. GIST, BTREE, etc. ) or an EXCLUDE constraint would treat it as an identifier to be quoted, rather than rendering it as is. The new behavior converts these types to lowercase and ensures they contain only valid SQL characters.
¶References: #4473
misc¶
[bug] [ext]
Implemented a more comprehensive assignment operation (e.g. “bulk replace”) when using association proxy with sets or dictionaries. Fixes the problem of redundant proxy objects being created to replace the old ones, which leads to excessive events and SQL and in the case of unique constraints will cause the flush to fail.
¶References: #2642
[change] [tests]
The test system has removed support for Nose, which is unmaintained for several years and is producing warnings under Python 3. The test suite is currently standardized on Pytest. Pull request courtesy Parth Shandilya.
¶References: #4460
1.3.0b2¶
Released: January 25, 2019general¶
[general] [change]
A large change throughout the library has ensured that all objects, parameters, and behaviors which have been noted as deprecated or legacy now emit
¶DeprecationWarning
warnings when invoked.As the Python 3 interpreter now defaults to displaying deprecation warnings, as well as that modern test suites based on tools like tox and pytest tend to display deprecation warnings, this change should make it easier to note what API features are obsolete. A major rationale for this change is so that long- deprecated features that nonetheless still see continue to see real world use can finally be removed in the near future; the biggest example of this are theSessionExtension
andMapperExtension
classes as well as a handful of other pre-event extension hooks, which have been deprecated since version 0.7 but still remain in the library. Another is that several major longstanding behaviors are to be deprecated as well, including the threadlocal engine strategy, the convert_unicode flag, and non primary mappers.References: #4393
orm¶
[orm] [feature]
Implemented a new feature whereby the
¶AliasedClass
construct can now be used as the target of arelationship()
. This allows the concept of “non primary mappers” to no longer be necessary, as theAliasedClass
is much easier to configure and automatically inherits all the relationships of the mapped class, as well as preserves the ability for loader options to work normally.References: #4423
[orm] [feature]
Added new
¶MapperEvents.before_mapper_configured()
event. This event complements the other “configure” stage mapper events with a per mapper event that receives eachMapper
right before its configure step, and additionally may be used to prevent or delay the configuration of specificMapper
objects using a new return valueorm.interfaces.EXT_SKIP
. See the documentation link for an example.References: #4397
[orm] [bug]
Fixed long-standing issue where duplicate collection members would cause a backref to delete the association between the member and its parent object when one of the duplicates were removed, as occurs as a side effect of swapping two objects in one statement.
¶References: #1103
[orm] [bug]
Extended the fix first made as part of #3287, where a loader option made against a subclass using a wildcard would extend itself to include application of the wildcard to attributes on the super classes as well, to a “bound” loader option as well, e.g. in an expression like
¶Load(SomeSubClass).load_only('foo')
. Columns that are part of the parent class ofSomeSubClass
will also be excluded in the same way as if the unbound optionload_only('foo')
were used.References: #4373
[orm] [bug]
Improved error messages emitted by the ORM in the area of loader option traversal. This includes early detection of mis-matched loader strategies along with a clearer explanation why these strategies don’t match.
¶References: #4433
[orm] [bug]
The “remove” event for collections is now called before the item is removed in the case of the
¶collection.remove()
method, as is consistent with the behavior for most other forms of collection item removal (such as__delitem__
, replacement under__setitem__
). Forpop()
methods, the remove event still fires after the operation.[orm] [bug] [engine]
Added accessors for execution options to Core and ORM, via
¶Query.get_execution_options()
,Connection.get_execution_options()
,Engine.get_execution_options()
, andExecutable.get_execution_options()
. PR courtesy Daniel Lister.References: #4464
[orm] [bug]
Fixed issue in association proxy due to #3423 which caused the use of custom
¶PropComparator
objects with hybrid attributes, such as the one demonstrated in thedictlike-polymorphic
example to not function within an association proxy. The strictness that was added in #3423 has been relaxed, and additional logic to accommodate for an association proxy that links to a custom hybrid have been added.References: #4446
[orm] [bug]
Implemented the
¶.get_history()
method, which also implies availability ofAttributeState.history
, forsynonym()
attributes. Previously, trying to access attribute history via a synonym would raise anAttributeError
.References: #3777
[orm] [change]
Added a new function
¶close_all_sessions()
which takes over the task of theSession.close_all()
method, which is now deprecated as this is confusing as a classmethod. Pull request courtesy Augustin Trancart.References: #4412
orm declarative¶
[orm declarative] [bug]
Added a
¶__clause_element__()
method toColumnProperty
which can allow the usage of a not-fully-declared column or deferred attribute in a declarative mapped class slightly more friendly when it’s used in a constraint or other column-oriented scenario within the class declaration, though this still can’t work in open-ended expressions; prefer to call theColumnProperty.expression
attribute if receivingTypeError
.References: #4372
engine¶
[engine] [feature]
Added public accessor
¶QueuePool.timeout()
that returns the configured timeout for aQueuePool
object. Pull request courtesy Irina Delamare.References: #3689
[engine] [change]
The “threadlocal” engine strategy which has been a legacy feature of SQLAlchemy since around version 0.2 is now deprecated, along with the
¶Pool.threadlocal
parameter ofPool
which has no effect in most modern use cases.References: #4393
sql¶
[sql] [feature]
Amended the
¶AnsiFunction
class, the base of common SQL functions likeCURRENT_TIMESTAMP
, to accept positional arguments like a regular ad-hoc function. This to suit the case that many of these functions on specific backends accept arguments such as “fractional seconds” precision and such. If the function is created with arguments, it renders the parenthesis and the arguments. If no arguments are present, the compiler generates the non-parenthesized form.References: #4386
[sql] [change]
The
¶create_engine.convert_unicode
andString.convert_unicode
parameters have been deprecated. These parameters were built back when most Python DBAPIs had little to no support for Python Unicode objects, and SQLAlchemy needed to take on the very complex task of marshalling data and SQL strings between Unicode and bytestrings throughout the system in a performant way. Thanks to Python 3, DBAPIs were compelled to adapt to Unicode-aware APIs and today all DBAPIs supported by SQLAlchemy support Unicode natively, including on Python 2, allowing this long-lived and very complicated feature to finally be (mostly) removed. There are still of course a few Python 2 edge cases where SQLAlchemy has to deal with Unicode however these are handled automatically; in modern use, there should be no need for end-user interaction with these flags.References: #4393
mssql¶
[mssql] [bug]
The
¶literal_processor
for theUnicode
andUnicodeText
datatypes now render anN
character in front of the literal string expression as required by SQL Server for Unicode string values rendered in SQL expressions.References: #4442
1.3.0b1¶
Released: November 16, 2018orm¶
[orm] [feature]
Added new feature
¶Query.only_return_tuples()
. Causes theQuery
object to return keyed tuple objects unconditionally even if the query is against a single entity. Pull request courtesy Eric Atkin.This change is also backported to: 1.2.5
[orm] [feature]
Added new flag
¶Session.bulk_save_objects.preserve_order
to theSession.bulk_save_objects()
method, which defaults to True. When set to False, the given mappings will be grouped into inserts and updates per each object type, to allow for greater opportunities to batch common operations together. Pull request courtesy Alessandro Cucci.[orm] [feature]
The “selectin” loader strategy now omits the JOIN in the case of a simple one-to-many load, where it instead relies loads only from the related table, relying upon the foreign key columns of the related table in order to match up to primary keys in the parent table. This optimization can be disabled by setting the
¶relationship.omit_join
flag to False. Many thanks to Jayson Reis for the efforts on this.References: #4340
[orm] [feature]
Added
¶.info
dictionary to theInstanceState
class, the object that comes from callinginspect()
on a mapped object.References: #4257
[orm] [bug]
Fixed bug where use of
¶Lateral
construct in conjunction withQuery.join()
as well asQuery.select_entity_from()
would not apply clause adaption to the right side of the join. “lateral” introduces the use case of the right side of a join being correlatable. Previously, adaptation of this clause wasn’t considered. Note that in 1.2 only, a selectable introduced byQuery.subquery()
is still not adapted due to #4304; the selectable needs to be produced by theselect()
function to be the right side of the “lateral” join.This change is also backported to: 1.2.12
References: #4334
[orm] [bug]
Fixed issue regarding passive_deletes=”all”, where the foreign key attribute of an object is maintained with its value even after the object is removed from its parent collection. Previously, the unit of work would set this to NULL even though passive_deletes indicated it should not be modified.
¶References: #3844
[orm] [bug]
Improved the behavior of a relationship-bound many-to-one object expression such that the retrieval of column values on the related object are now resilient against the object being detached from its parent
¶Session
, even if the attribute has been expired. New features within theInstanceState
are used to memoize the last known value of a particular column attribute before its expired, so that the expression can still evaluate when the object is detached and expired at the same time. Error conditions are also improved using modern attribute state features to produce more specific messages as needed.References: #4359
[orm] [bug] [mysql] [postgresql]
The ORM now doubles the “FOR UPDATE” clause within the subquery that renders in conjunction with joined eager loading in some cases, as it has been observed that MySQL does not lock the rows from a subquery. This means the query renders with two FOR UPDATE clauses; note that on some backends such as Oracle, FOR UPDATE clauses on subqueries are silently ignored since they are unnecessary. Additionally, in the case of the “OF” clause used primarily with PostgreSQL, the FOR UPDATE is rendered only on the inner subquery when this is used so that the selectable can be targeted to the table within the SELECT statement.
¶References: #4246
[orm] [bug]
Refactored
¶Query.join()
to further clarify the individual components of structuring the join. This refactor adds the ability forQuery.join()
to determine the most appropriate “left” side of the join when there is more than one element in the FROM list or the query is against multiple entities. If more than one FROM/entity matches, an error is raised that asks for an ON clause to be specified to resolve the ambiguity. In particular this targets the regression we saw in #4363 but is also of general use. The codepaths withinQuery.join()
are now easier to follow and the error cases are decided more specifically at an earlier point in the operation.References: #4365
[orm] [bug]
Fixed long-standing issue in
¶Query
where a scalar subquery such as produced byQuery.exists()
,Query.as_scalar()
and other derivations fromQuery.statement
would not correctly be adapted when used in a newQuery
that required entity adaptation, such as when the query were turned into a union, or a from_self(), etc. The change removes the “no adaptation” annotation from theselect()
object produced by theQuery.statement
accessor.References: #4304
[orm] [bug]
An informative exception is re-raised when a primary key value is not sortable in Python during an ORM flush under Python 3, such as an
¶Enum
that has no__lt__()
method; normally Python 3 raises aTypeError
in this case. The flush process sorts persistent objects by primary key in Python so the values must be sortable.References: #4232
[orm] [bug]
Removed the collection converter used by the
MappedCollection
class. This converter was used only to assert that the incoming dictionary keys matched that of their corresponding objects, and only during a bulk set operation. The converter can interfere with a custom validator orAttributeEvents.bulk_replace()
listener that wants to convert incoming values further. TheTypeError
which would be raised by this converter when an incoming key didn’t match the value is removed; incoming values during a bulk assignment will be keyed to their value-generated key, and not the key that’s explicitly present in the dictionary.Overall, @converter is superseded by the
¶AttributeEvents.bulk_replace()
event handler added as part of #3896.References: #3604
[orm] [bug]
Added new behavior to the lazy load that takes place when the “old” value of a many-to-one is retrieved, such that exceptions which would be raised due to either
¶lazy="raise"
or a detached session error are skipped.References: #4353
[orm] [bug]
A long-standing oversight in the ORM, the
__delete__
method for a many- to-one relationship was non-functional, e.g. for an operation such asdel a.b
. This is now implemented and is equivalent to setting the attribute toNone
.See also
References: #4354
orm declarative¶
[bug] [declarative] [orm]
Fixed bug where declarative would not update the state of the
¶Mapper
as far as what attributes were present, when additional attributes were added or removed after the mapper attribute collections had already been called and memoized. Additionally, aNotImplementedError
is now raised if a fully mapped attribute (e.g. column, relationship, etc.) is deleted from a class that is currently mapped, since the mapper will not function correctly if the attribute has been removed.References: #4133
engine¶
[engine] [feature]
Added new “lifo” mode to
¶QueuePool
, typically enabled by setting the flagcreate_engine.pool_use_lifo
to True. “lifo” mode means the same connection just checked in will be the first to be checked out again, allowing excess connections to be cleaned up from the server side during periods of the pool being only partially utilized. Pull request courtesy Taem Park.
sql¶
[sql] [feature]
Refactored
¶SQLCompiler
to expose aSQLCompiler.group_by_clause()
method similar to theSQLCompiler.order_by_clause()
andSQLCompiler.limit_clause()
methods, which can be overridden by dialects to customize how GROUP BY renders. Pull request courtesy Samuel Chou.This change is also backported to: 1.2.13
[sql] [feature]
Added
¶Sequence
to the “string SQL” system that will render a meaningful string expression ("<next sequence value: my_sequence>"
) when stringifying without a dialect a statement that includes a “sequence nextvalue” expression, rather than raising a compilation error.References: #4144
[sql] [feature]
Added new naming convention tokens
column_0N_name
,column_0_N_name
, etc., which will render the names / keys / labels for all columns referenced by a particular constraint in a sequence. In order to accommodate for the length of such a naming convention, the SQL compiler’s auto-truncation feature now applies itself to constraint names as well, which creates a shortened, deterministically generated name for the constraint that will apply to a target backend without going over the character limit of that backend.The change also repairs two other issues. One is that the
¶column_0_key
token wasn’t available even though this token was documented, the other was that thereferred_column_0_name
token would inadvertently render the.key
and not the.name
of the column if these two values were different.References: #3989
[sql] [feature]
Added new logic to the “expanding IN” bound parameter feature whereby if the given list is empty, a special “empty set” expression that is specific to different backends is generated, thus allowing IN expressions to be fully dynamic including empty IN expressions.
¶References: #4271
[sql] [feature]
The Python builtin
¶dir()
is now supported for a SQLAlchemy “properties” object, such as that of a Core columns collection (e.g..c
),mapper.attrs
, etc. Allows iPython autocompletion to work as well. Pull request courtesy Uwe Korn.[sql] [feature]
Added new feature
¶FunctionElement.as_comparison()
which allows a SQL function to act as a binary comparison operation that can work within the ORM.References: #3831
[sql] [bug]
Added “like” based operators as “comparison” operators, including
¶ColumnOperators.startswith()
ColumnOperators.endswith()
ColumnOperators.ilike()
ColumnOperators.notilike()
among many others, so that all of these operators can be the basis for an ORM “primaryjoin” condition.References: #4302
[sql] [bug]
Fixed issue with
TypeEngine.bind_expression()
andTypeEngine.column_expression()
methods where these methods would not work if the target type were part of aVariant
, or other target type of aTypeDecorator
. Additionally, the SQL compiler now calls upon the dialect-level implementation when it renders these methods so that dialects can now provide for SQL-level processing for built-in types.See also
TypeEngine methods bind_expression, column_expression work with Variant, type-specific types
References: #3981
postgresql¶
[postgresql] [feature]
Added new PG type
¶postgresql.REGCLASS
which assists in casting table names to OID values. Pull request courtesy Sebastian Bank.This change is also backported to: 1.2.7
References: #4160
[postgresql] [feature]
Added rudimental support for reflection of PostgreSQL partitioned tables, e.g. that relkind=’p’ is added to reflection queries that return table information.
¶References: #4237
mysql¶
[mysql] [feature]
Support added for the “WITH PARSER” syntax of CREATE FULLTEXT INDEX in MySQL, using the
¶mysql_with_parser
keyword argument. Reflection is also supported, which accommodates MySQL’s special comment format for reporting on this option as well. Additionally, the “FULLTEXT” and “SPATIAL” index prefixes are now reflected back into themysql_prefix
index option.References: #4219
[mysql] [feature]
Added support for the parameters in an ON DUPLICATE KEY UPDATE statement on MySQL to be ordered, since parameter order in a MySQL UPDATE clause is significant, in a similar manner as that described at Parameter-Ordered Updates. Pull request courtesy Maxim Bublis.
¶[mysql] [feature]
The “pre-ping” feature of the connection pool now uses the
¶ping()
method of the DBAPI connection in the case of mysqlclient, PyMySQL and mysql-connector-python. Pull request courtesy Maxim Bublis.
sqlite¶
[sqlite] [feature]
Added support for SQLite’s json functionality via the new SQLite implementation for
types.JSON
,sqlite.JSON
. The name used for the type isJSON
, following an example found at SQLite’s own documentation. Pull request courtesy Ilja Everilä.See also
References: #3850
[sqlite] [feature]
Implemented the SQLite
¶ON CONFLICT
clause as understood at the DDL level, e.g. for primary key, unique, and CHECK constraints as well as specified on aColumn
to satisfy inline primary key and NOT NULL. Pull request courtesy Denis Kataev.References: #4360
mssql¶
[mssql] [feature]
Added
fast_executemany=True
parameter to the SQL Server pyodbc dialect, which enables use of pyodbc’s new performance feature of the same name when using Microsoft ODBC drivers.See also
References: #4158
[mssql] [bug]
Deprecated the use of
¶Sequence
with SQL Server in order to affect the “start” and “increment” of the IDENTITY value, in favor of new parametersmssql_identity_start
andmssql_identity_increment
which set these parameters directly.Sequence
will be used to generate realCREATE SEQUENCE
DDL with SQL Server in a future release.References: #4362
oracle¶
[oracle] [feature]
Added a new event currently used only by the cx_Oracle dialect,
¶DialectEvents.setiputsizes()
. The event passes a dictionary ofBindParameter
objects to DBAPI-specific type objects that will be passed, after conversion to parameter names, to the cx_Oraclecursor.setinputsizes()
method. This allows both visibility into the setinputsizes process as well as the ability to alter the behavior of what datatypes are passed to this method.This change is also backported to: 1.2.9
References: #4290
[oracle] [bug]
Updated the parameters that can be sent to the cx_Oracle DBAPI to both allow for all current parameters as well as for future parameters not added yet. In addition, removed unused parameters that were deprecated in version 1.2, and additionally we are now defaulting “threaded” to False.
¶References: #4369
[oracle] [bug]
The Oracle dialect will no longer use the NCHAR/NCLOB datatypes represent generic unicode strings or clob fields in conjunction with
¶Unicode
andUnicodeText
unless the flaguse_nchar_for_unicode=True
is passed tocreate_engine()
- this includes CREATE TABLE behavior as well assetinputsizes()
for bound parameters. On the read side, automatic Unicode conversion under Python 2 has been added to CHAR/VARCHAR/CLOB result rows, to match the behavior of cx_Oracle under Python 3. In order to mitigate the performance hit under Python 2, SQLAlchemy’s very performant (when C extensions are built) native Unicode handlers are used under Python 2.References: #4242
misc¶
[feature] [ext]
Added new attribute
¶Query.lazy_loaded_from
which is populated with anInstanceState
that is using thisQuery
in order to lazy load a relationship. The rationale for this is that it serves as a hint for the horizontal sharding feature to use, such that the identity token of the state can be used as the default identity token to use for the query within id_chooser().This change is also backported to: 1.2.9
References: #4243
[feature] [ext]
Added new feature
¶BakedQuery.to_query()
, which allows for a clean way of using oneBakedQuery
as a subquery inside of anotherBakedQuery
without needing to refer explicitly to aSession
.References: #4318
[feature] [ext]
The
¶AssociationProxy
now has standard column comparison operations such asColumnOperators.like()
andColumnOperators.startswith()
available when the target attribute is a plain column - the EXISTS expression that joins to the target table is rendered as usual, but the column expression is then use within the WHERE criteria of the EXISTS. Note that this alters the behavior of the.contains()
method on the association proxy to make use ofColumnOperators.contains()
when used on a column-based attribute.References: #4351
[feature] [ext]
Added support for bulk
¶Query.update()
andQuery.delete()
to theShardedQuery
class within the horizontal sharding extension. This also adds an additional expansion hook to the bulk update/delete methodsQuery._execute_crud()
.References: #4196
[bug] [ext]
Reworked
¶AssociationProxy
to store state that’s specific to a parent class in a separate object, so that a singleAssociationProxy
can serve for multiple parent classes, as is intrinsic to inheritance, without any ambiguity in the state returned by it. A new methodAssociationProxy.for_class()
is added to allow inspection of class-specific state.References: #3423
[bug] [ext]
The long-standing behavior of the association proxy collection maintaining only a weak reference to the parent object is reverted; the proxy will now maintain a strong reference to the parent for as long as the proxy collection itself is also in memory, eliminating the “stale association proxy” error. This change is being made on an experimental basis to see if any use cases arise where it causes side effects.
See also
References: #4268
[bug] [ext]
Fixed multiple issues regarding de-association of scalar objects with the association proxy.
¶del
now works, and additionally a new flagAssociationProxy.cascade_scalar_deletes
is added, which when set to True indicates that setting a scalar attribute toNone
or deleting viadel
will also set the source association toNone
.References: #4308