Release: 0.9.8 | Release Date: October 13, 2014

SQLAlchemy 0.9 Documentation

ORM Internals

Key ORM constructs, not otherwise covered in other sections, are listed here.

class sqlalchemy.orm.state.AttributeState(state, key)

Provide an inspection interface corresponding to a particular attribute on a particular mapped object.

The AttributeState object is accessed via the InstanceState.attrs collection of a particular InstanceState:

from sqlalchemy import inspect

insp = inspect(some_mapped_object)
attr_state = insp.attrs.some_attribute
history

Return the current pre-flush change history for this attribute, via the History interface.

This method will not emit loader callables if the value of the attribute is unloaded.

See also

AttributeState.load_history() - retrieve history using loader callables if the value is not locally present.

attributes.get_history() - underlying function

load_history()

Return the current pre-flush change history for this attribute, via the History interface.

This method will emit loader callables if the value of the attribute is unloaded.

See also

AttributeState.history

attributes.get_history() - underlying function

New in version 0.9.0.

loaded_value

The current value of this attribute as loaded from the database.

If the value has not been loaded, or is otherwise not present in the object’s dictionary, returns NO_VALUE.

value

Return the value of this attribute.

This operation is equivalent to accessing the object’s attribute directly or via getattr(), and will fire off any pending loader callables if needed.

class sqlalchemy.orm.instrumentation.ClassManager(class_)

Bases: __builtin__.dict

tracks state information at the class level.

__le__
inherited from the __le__ attribute of dict

x.__le__(y) <==> x<=y

__lt__
inherited from the __lt__ attribute of dict

x.__lt__(y) <==> x<y

__ne__
inherited from the __ne__ attribute of dict

x.__ne__(y) <==> x!=y

clear() → None. Remove all items from D.
inherited from the clear() method of dict
copy() → a shallow copy of D
inherited from the copy() method of dict
dispose()

Dissasociate this manager from its class.

static fromkeys(S[, v]) → New dict with keys from S and values equal to v.
inherited from the fromkeys() method of dict

v defaults to None.

get(k[, d]) → D[k] if k in D, else d. d defaults to None.
inherited from the get() method of dict
has_key(k) → True if D has a key k, else False
inherited from the has_key() method of dict
has_parent(state, key, optimistic=False)

TODO

items() → list of D's (key, value) pairs, as 2-tuples
inherited from the items() method of dict
iteritems() → an iterator over the (key, value) items of D
inherited from the iteritems() method of dict
iterkeys() → an iterator over the keys of D
inherited from the iterkeys() method of dict
itervalues() → an iterator over the values of D
inherited from the itervalues() method of dict
keys() → list of D's keys
inherited from the keys() method of dict
manage()

Mark this instance as the manager for its class.

original_init

x.__init__(...) initializes x; see help(type(x)) for signature

pop(k[, d]) → v, remove specified key and return the corresponding value.
inherited from the pop() method of dict

If key is not found, d is returned if given, otherwise KeyError is raised

popitem() → (k, v), remove and return some (key, value) pair as a
inherited from the popitem() method of dict

2-tuple; but raise KeyError if D is empty.

setdefault(k[, d]) → D.get(k,d), also set D[k]=d if k not in D
inherited from the setdefault() method of dict
classmethod state_getter()

Return a (instance) -> InstanceState callable.

“state getter” callables should raise either KeyError or AttributeError if no InstanceState could be found for the instance.

unregister()

remove all instrumentation established by this ClassManager.

update([E, ]**F) → None. Update D from dict/iterable E and F.
inherited from the update() method of dict

If E present and has a .keys() method, does: for k in E: D[k] = E[k] If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v In either case, this is followed by: for k in F: D[k] = F[k]

values() → list of D's values
inherited from the values() method of dict
viewitems() → a set-like object providing a view on D's items
inherited from the viewitems() method of dict
viewkeys() → a set-like object providing a view on D's keys
inherited from the viewkeys() method of dict
viewvalues() → an object providing a view on D's values
inherited from the viewvalues() method of dict
class sqlalchemy.orm.properties.ColumnProperty(*columns, **kwargs)

Bases: sqlalchemy.orm.interfaces.StrategizedProperty

Describes an object attribute that corresponds to a table column.

Public constructor is the orm.column_property() function.

class Comparator(prop, parentmapper, adapt_to_entity=None)

Bases: sqlalchemy.orm.interfaces.PropComparator

Produce boolean, comparison, and other operators for ColumnProperty attributes.

See the documentation for PropComparator for a brief overview.

See also:

PropComparator

ColumnOperators

Redefining and Creating New Operators

TypeEngine.comparator_factory

__eq__(other)
inherited from the __eq__() method of ColumnOperators

Implement the == operator.

In a column context, produces the clause a = b. If the target is None, produces a IS NULL.

__le__(other)
inherited from the __le__() method of ColumnOperators

Implement the <= operator.

In a column context, produces the clause a <= b.

__lt__(other)
inherited from the __lt__() method of ColumnOperators

Implement the < operator.

In a column context, produces the clause a < b.

__ne__(other)
inherited from the __ne__() method of ColumnOperators

Implement the != operator.

In a column context, produces the clause a != b. If the target is None, produces a IS NOT NULL.

adapt_to_entity(adapt_to_entity)
inherited from the adapt_to_entity() method of PropComparator

Return a copy of this PropComparator which will use the given AliasedInsp to produce corresponding expressions.

adapter
inherited from the adapter attribute of PropComparator

Produce a callable that adapts column expressions to suit an aliased version of this comparator.

any(criterion=None, **kwargs)
inherited from the any() method of PropComparator

Return true if this collection contains any member that meets the given criterion.

The usual implementation of any() is RelationshipProperty.Comparator.any().

Parameters:
  • criterion – an optional ClauseElement formulated against the member class’ table or attributes.
  • **kwargs – key/value pairs corresponding to member class attribute names which will be compared via equality to the corresponding values.
asc()
inherited from the asc() method of ColumnOperators

Produce a asc() clause against the parent object.

between(cleft, cright, symmetric=False)
inherited from the between() method of ColumnOperators

Produce a between() clause against the parent object, given the lower and upper range.

collate(collation)
inherited from the collate() method of ColumnOperators

Produce a collate() clause against the parent object, given the collation string.

concat(other)
inherited from the concat() method of ColumnOperators

Implement the ‘concat’ operator.

In a column context, produces the clause a || b, or uses the concat() operator on MySQL.

contains(other, **kwargs)
inherited from the contains() method of ColumnOperators

Implement the ‘contains’ operator.

In a column context, produces the clause LIKE '%<other>%'

desc()
inherited from the desc() method of ColumnOperators

Produce a desc() clause against the parent object.

distinct()
inherited from the distinct() method of ColumnOperators

Produce a distinct() clause against the parent object.

endswith(other, **kwargs)
inherited from the endswith() method of ColumnOperators

Implement the ‘endswith’ operator.

In a column context, produces the clause LIKE '%<other>'

has(criterion=None, **kwargs)
inherited from the has() method of PropComparator

Return true if this element references a member which meets the given criterion.

The usual implementation of has() is RelationshipProperty.Comparator.has().

Parameters:
  • criterion – an optional ClauseElement formulated against the member class’ table or attributes.
  • **kwargs – key/value pairs corresponding to member class attribute names which will be compared via equality to the corresponding values.
ilike(other, escape=None)
inherited from the ilike() method of ColumnOperators

Implement the ilike operator.

In a column context, produces the clause a ILIKE other.

E.g.:

select([sometable]).where(sometable.c.column.ilike("%foobar%"))
Parameters:
  • other – expression to be compared
  • escape

    optional escape character, renders the ESCAPE keyword, e.g.:

    somecolumn.ilike("foo/%bar", escape="/")
in_(other)
inherited from the in_() method of ColumnOperators

Implement the in operator.

In a column context, produces the clause a IN other. “other” may be a tuple/list of column expressions, or a select() construct.

is_(other)
inherited from the is_() method of ColumnOperators

Implement the IS operator.

Normally, IS is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS may be desirable if comparing to boolean values on certain platforms.

New in version 0.7.9.

isnot(other)
inherited from the isnot() method of ColumnOperators

Implement the IS NOT operator.

Normally, IS NOT is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS NOT may be desirable if comparing to boolean values on certain platforms.

New in version 0.7.9.

like(other, escape=None)
inherited from the like() method of ColumnOperators

Implement the like operator.

In a column context, produces the clause a LIKE other.

E.g.:

select([sometable]).where(sometable.c.column.like("%foobar%"))
Parameters:
  • other – expression to be compared
  • escape

    optional escape character, renders the ESCAPE keyword, e.g.:

    somecolumn.like("foo/%bar", escape="/")
match(other, **kwargs)
inherited from the match() method of ColumnOperators

Implements a database-specific ‘match’ operator.

match() attempts to resolve to a MATCH-like function or operator provided by the backend. Examples include:

  • Postgresql - renders x @@ to_tsquery(y)
  • MySQL - renders MATCH (x) AGAINST (y IN BOOLEAN MODE)
  • Oracle - renders CONTAINS(x, y)
  • other backends may provide special implementations; some backends such as SQLite have no support.
notilike(other, escape=None)
inherited from the notilike() method of ColumnOperators

implement the NOT ILIKE operator.

This is equivalent to using negation with ColumnOperators.ilike(), i.e. ~x.ilike(y).

New in version 0.8.

notin_(other)
inherited from the notin_() method of ColumnOperators

implement the NOT IN operator.

This is equivalent to using negation with ColumnOperators.in_(), i.e. ~x.in_(y).

New in version 0.8.

notlike(other, escape=None)
inherited from the notlike() method of ColumnOperators

implement the NOT LIKE operator.

This is equivalent to using negation with ColumnOperators.like(), i.e. ~x.like(y).

New in version 0.8.

nullsfirst()
inherited from the nullsfirst() method of ColumnOperators

Produce a nullsfirst() clause against the parent object.

nullslast()
inherited from the nullslast() method of ColumnOperators

Produce a nullslast() clause against the parent object.

of_type(class_)
inherited from the of_type() method of PropComparator

Redefine this object in terms of a polymorphic subclass.

Returns a new PropComparator from which further criterion can be evaluated.

e.g.:

query.join(Company.employees.of_type(Engineer)).\
   filter(Engineer.name=='foo')
Parameters:class_ – a class or mapper indicating that criterion will be against this specific subclass.
op(opstring, precedence=0, is_comparison=False)
inherited from the op() method of Operators

produce a generic operator function.

e.g.:

somecolumn.op("*")(5)

produces:

somecolumn * 5

This function can also be used to make bitwise operators explicit. For example:

somecolumn.op('&')(0xff)

is a bitwise AND of the value in somecolumn.

Parameters:
  • operator – a string which will be output as the infix operator between this element and the expression passed to the generated function.
  • precedence

    precedence to apply to the operator, when parenthesizing expressions. A lower number will cause the expression to be parenthesized when applied against another operator with higher precedence. The default value of 0 is lower than all operators except for the comma (,) and AS operators. A value of 100 will be higher or equal to all operators, and -100 will be lower than or equal to all operators.

    New in version 0.8: - added the ‘precedence’ argument.

  • is_comparison

    if True, the operator will be considered as a “comparison” operator, that is which evaulates to a boolean true/false value, like ==, >, etc. This flag should be set so that ORM relationships can establish that the operator is a comparison operator when used in a custom join condition.

    New in version 0.9.2: - added the Operators.op.is_comparison flag.

startswith(other, **kwargs)
inherited from the startswith() method of ColumnOperators

Implement the startwith operator.

In a column context, produces the clause LIKE '<other>%'

ColumnProperty.__init__(*columns, **kwargs)

Construct a new ColumnProperty object.

This constructor is mirrored as a public API function; see column_property() for a full usage and argument description.

ColumnProperty.cascade_iterator(type_, state, visited_instances=None, halt_on=None)
inherited from the cascade_iterator() method of MapperProperty

Iterate through instances related to the given instance for a particular ‘cascade’, starting with this MapperProperty.

Return an iterator3-tuples (instance, mapper, state).

Note that the ‘cascade’ collection on this MapperProperty is checked first for the given type before cascade_iterator is called.

See PropertyLoader for the related instance implementation.

ColumnProperty.class_attribute
inherited from the class_attribute attribute of MapperProperty

Return the class-bound descriptor corresponding to this MapperProperty.

This is basically a getattr() call:

return getattr(self.parent.class_, self.key)

I.e. if this MapperProperty were named addresses, and the class to which it is mapped is User, this sequence is possible:

>>> from sqlalchemy import inspect
>>> mapper = inspect(User)
>>> addresses_property = mapper.attrs.addresses
>>> addresses_property.class_attribute is User.addresses
True
>>> User.addresses.property is addresses_property
True
ColumnProperty.compare(operator, value, **kw)
inherited from the compare() method of MapperProperty

Return a compare operation for the columns represented by this MapperProperty to the given value, which may be a column value or an instance. ‘operator’ is an operator from the operators module, or from sql.Comparator.

By default uses the PropComparator attached to this MapperProperty under the attribute name “comparator”.

ColumnProperty.expression

Return the primary column or expression for this ColumnProperty.

ColumnProperty.extension_type = symbol('NOT_EXTENSION')
ColumnProperty.info
inherited from the info attribute of MapperProperty

Info dictionary associated with the object, allowing user-defined data to be associated with this MapperProperty.

The dictionary is generated when first accessed. Alternatively, it can be specified as a constructor argument to the column_property(), relationship(), or composite() functions.

New in version 0.8: Added support for .info to all MapperProperty subclasses.

ColumnProperty.init()
inherited from the init() method of MapperProperty

Called after all mappers are created to assemble relationships between mappers and perform other post-mapper-creation initialization steps.

ColumnProperty.is_primary()
inherited from the is_primary() method of MapperProperty

Return True if this MapperProperty‘s mapper is the primary mapper for its class.

This flag is used to indicate that the MapperProperty can define attribute instrumentation for the class at the class level (as opposed to the individual instance level).

class sqlalchemy.orm.descriptor_props.CompositeProperty(class_, *attrs, **kwargs)

Bases: sqlalchemy.orm.descriptor_props.DescriptorProperty

Defines a “composite” mapped attribute, representing a collection of columns as one attribute.

CompositeProperty is constructed using the composite() function.

class Comparator(prop, parentmapper, adapt_to_entity=None)

Bases: sqlalchemy.orm.interfaces.PropComparator

Produce boolean, comparison, and other operators for CompositeProperty attributes.

See the example in Redefining Comparison Operations for Composites for an overview of usage , as well as the documentation for PropComparator.

See also:

PropComparator

ColumnOperators

Redefining and Creating New Operators

TypeEngine.comparator_factory

CompositeProperty.__init__(class_, *attrs, **kwargs)

Construct a new CompositeProperty object.

This constructor is mirrored as a public API function; see composite() for a full usage and argument description.

CompositeProperty.do_init()

Initialization which occurs after the CompositeProperty has been associated with its parent mapper.

CompositeProperty.get_history(state, dict_, passive=symbol('PASSIVE_OFF'))

Provided for userland code that uses attributes.get_history().

class sqlalchemy.orm.attributes.Event(attribute_impl, op)

A token propagated throughout the course of a chain of attribute events.

Serves as an indicator of the source of the event and also provides a means of controlling propagation across a chain of attribute operations.

The Event object is sent as the initiator argument when dealing with the AttributeEvents.append(), AttributeEvents.set(), and AttributeEvents.remove() events.

The Event object is currently interpreted by the backref event handlers, and is used to control the propagation of operations across two mutually-dependent attributes.

New in version 0.9.0.

impl = None

The AttributeImpl which is the current event initiator.

op = None

The symbol OP_APPEND, OP_REMOVE or OP_REPLACE, indicating the source operation.

class sqlalchemy.orm.interfaces._InspectionAttr

A base class applied to all ORM objects that can be returned by the inspect() function.

The attributes defined here allow the usage of simple boolean checks to test basic facts about the object returned.

While the boolean checks here are basically the same as using the Python isinstance() function, the flags here can be used without the need to import all of these classes, and also such that the SQLAlchemy class system can change while leaving the flags here intact for forwards-compatibility.

extension_type = symbol('NOT_EXTENSION')

The extension type, if any. Defaults to interfaces.NOT_EXTENSION

New in version 0.8.0.

is_aliased_class = False

True if this object is an instance of AliasedClass.

is_attribute = False

True if this object is a Python descriptor.

This can refer to one of many types. Usually a QueryableAttribute which handles attributes events on behalf of a MapperProperty. But can also be an extension type such as AssociationProxy or hybrid_property. The _InspectionAttr.extension_type will refer to a constant identifying the specific subtype.

is_clause_element = False

True if this object is an instance of ClauseElement.

is_instance = False

True if this object is an instance of InstanceState.

is_mapper = False

True if this object is an instance of Mapper.

is_property = False

True if this object is an instance of MapperProperty.

is_selectable = False

Return True if this object is an instance of Selectable.

class sqlalchemy.orm.state.InstanceState(obj, manager)

Bases: sqlalchemy.orm.base._InspectionAttr

tracks state information at the instance level.

The InstanceState is a key object used by the SQLAlchemy ORM in order to track the state of an object; it is created the moment an object is instantiated, typically as a result of instrumentation which SQLAlchemy applies to the __init__() method of the class.

InstanceState is also a semi-public object, available for runtime inspection as to the state of a mapped instance, including information such as its current status within a particular Session and details about data on individual attributes. The public API in order to acquire a InstanceState object is to use the inspect() system:

>>> from sqlalchemy import inspect
>>> insp = inspect(some_mapped_object)
__call__(state, passive)

__call__ allows the InstanceState to act as a deferred callable for loading expired attributes, which is also serializable (picklable).

attrs

Return a namespace representing each attribute on the mapped object, including its current value and history.

The returned object is an instance of AttributeState. This object allows inspection of the current data within an attribute as well as attribute history since the last flush.

detached

Return true if the object is detached.

dict

Return the instance dict used by the object.

Under normal circumstances, this is always synonymous with the __dict__ attribute of the mapped object, unless an alternative instrumentation system has been configured.

In the case that the actual object has been garbage collected, this accessor returns a blank dictionary.

expired_attributes

Return the set of keys which are ‘expired’ to be loaded by the manager’s deferred scalar loader, assuming no pending changes.

see also the unmodified collection which is intersected against this set when a refresh operation occurs.

has_identity

Return True if this object has an identity key.

This should always have the same value as the expression state.persistent or state.detached.

identity

Return the mapped identity of the mapped object. This is the primary key identity as persisted by the ORM which can always be passed directly to Query.get().

Returns None if the object has no primary key identity.

Note

An object which is transient or pending does not have a mapped identity until it is flushed, even if its attributes include primary key values.

identity_key

Return the identity key for the mapped object.

This is the key used to locate the object within the Session.identity_map mapping. It contains the identity as returned by identity within it.

mapper

Return the Mapper used for this mapepd object.

object

Return the mapped object represented by this InstanceState.

pending

Return true if the object is pending.

persistent

Return true if the object is persistent.

session

Return the owning Session for this instance, or None if none available.

Note that the result here can in some cases be different from that of obj in session; an object that’s been deleted will report as not in session, however if the transaction is still in progress, this attribute will still refer to that session. Only when the transaction is completed does the object become fully detached under normal circumstances.

transient

Return true if the object is transient.

unloaded

Return the set of keys which do not have a loaded value.

This includes expired attributes and any other attribute that was never populated or modified.

unmodified

Return the set of keys which have no uncommitted changes

unmodified_intersection(keys)

Return self.unmodified.intersection(keys).

class sqlalchemy.orm.attributes.InstrumentedAttribute(class_, key, impl=None, comparator=None, parententity=None, of_type=None)

Bases: sqlalchemy.orm.attributes.QueryableAttribute

Class bound instrumented attribute which adds basic descriptor methods.

See QueryableAttribute for a description of most features.

__delete__(instance)
__get__(instance, owner)
__set__(instance, value)
sqlalchemy.orm.interfaces.MANYTOONE = symbol('MANYTOONE')

Indicates the many-to-one direction for a relationship().

This symbol is typically used by the internals but may be exposed within certain API features.

sqlalchemy.orm.interfaces.MANYTOMANY = symbol('MANYTOMANY')

Indicates the many-to-many direction for a relationship().

This symbol is typically used by the internals but may be exposed within certain API features.

class sqlalchemy.orm.interfaces.MapperProperty

Bases: sqlalchemy.orm.base._MappedAttribute, sqlalchemy.orm.base._InspectionAttr

Manage the relationship of a Mapper to a single class attribute, as well as that attribute as it appears on individual instances of the class, including attribute instrumentation, attribute access, loading behavior, and dependency calculations.

The most common occurrences of MapperProperty are the mapped Column, which is represented in a mapping as an instance of ColumnProperty, and a reference to another class produced by relationship(), represented in the mapping as an instance of RelationshipProperty.

cascade = frozenset([])

The set of ‘cascade’ attribute names.

This collection is checked before the ‘cascade_iterator’ method is called.

cascade_iterator(type_, state, visited_instances=None, halt_on=None)

Iterate through instances related to the given instance for a particular ‘cascade’, starting with this MapperProperty.

Return an iterator3-tuples (instance, mapper, state).

Note that the ‘cascade’ collection on this MapperProperty is checked first for the given type before cascade_iterator is called.

See PropertyLoader for the related instance implementation.

class_attribute

Return the class-bound descriptor corresponding to this MapperProperty.

This is basically a getattr() call:

return getattr(self.parent.class_, self.key)

I.e. if this MapperProperty were named addresses, and the class to which it is mapped is User, this sequence is possible:

>>> from sqlalchemy import inspect
>>> mapper = inspect(User)
>>> addresses_property = mapper.attrs.addresses
>>> addresses_property.class_attribute is User.addresses
True
>>> User.addresses.property is addresses_property
True
compare(operator, value, **kw)

Return a compare operation for the columns represented by this MapperProperty to the given value, which may be a column value or an instance. ‘operator’ is an operator from the operators module, or from sql.Comparator.

By default uses the PropComparator attached to this MapperProperty under the attribute name “comparator”.

create_row_processor(context, path, mapper, row, adapter)

Return a 3-tuple consisting of three row processing functions.

do_init()

Perform subclass-specific initialization post-mapper-creation steps.

This is a template method called by the MapperProperty object’s init() method.

info

Info dictionary associated with the object, allowing user-defined data to be associated with this MapperProperty.

The dictionary is generated when first accessed. Alternatively, it can be specified as a constructor argument to the column_property(), relationship(), or composite() functions.

New in version 0.8: Added support for .info to all MapperProperty subclasses.

init()

Called after all mappers are created to assemble relationships between mappers and perform other post-mapper-creation initialization steps.

is_primary()

Return True if this MapperProperty‘s mapper is the primary mapper for its class.

This flag is used to indicate that the MapperProperty can define attribute instrumentation for the class at the class level (as opposed to the individual instance level).

merge(session, source_state, source_dict, dest_state, dest_dict, load, _recursive)

Merge the attribute represented by this MapperProperty from source to destination object

post_instrument_class(mapper)

Perform instrumentation adjustments that need to occur after init() has completed.

setup(context, entity, path, adapter, **kwargs)

Called by Query for the purposes of constructing a SQL statement.

Each MapperProperty associated with the target mapper processes the statement referenced by the query context, adding columns and/or criterion as appropriate.

sqlalchemy.orm.interfaces.NOT_EXTENSION = symbol('NOT_EXTENSION')

Symbol indicating an _InspectionAttr that’s not part of sqlalchemy.ext.

Is assigned to the _InspectionAttr.extension_type attibute.

sqlalchemy.orm.interfaces.ONETOMANY = symbol('ONETOMANY')

Indicates the one-to-many direction for a relationship().

This symbol is typically used by the internals but may be exposed within certain API features.

class sqlalchemy.orm.interfaces.PropComparator(prop, parentmapper, adapt_to_entity=None)

Bases: sqlalchemy.sql.operators.ColumnOperators

Defines boolean, comparison, and other operators for MapperProperty objects.

SQLAlchemy allows for operators to be redefined at both the Core and ORM level. PropComparator is the base class of operator redefinition for ORM-level operations, including those of ColumnProperty, RelationshipProperty, and CompositeProperty.

Note

With the advent of Hybrid properties introduced in SQLAlchemy 0.7, as well as Core-level operator redefinition in SQLAlchemy 0.8, the use case for user-defined PropComparator instances is extremely rare. See Hybrid Attributes as well as Redefining and Creating New Operators.

User-defined subclasses of PropComparator may be created. The built-in Python comparison and math operator methods, such as operators.ColumnOperators.__eq__(), operators.ColumnOperators.__lt__(), and operators.ColumnOperators.__add__(), can be overridden to provide new operator behavior. The custom PropComparator is passed to the MapperProperty instance via the comparator_factory argument. In each case, the appropriate subclass of PropComparator should be used:

# definition of custom PropComparator subclasses

from sqlalchemy.orm.properties import \
                        ColumnProperty,\
                        CompositeProperty,\
                        RelationshipProperty

class MyColumnComparator(ColumnProperty.Comparator):
    def __eq__(self, other):
        return self.__clause_element__() == other

class MyRelationshipComparator(RelationshipProperty.Comparator):
    def any(self, expression):
        "define the 'any' operation"
        # ...

class MyCompositeComparator(CompositeProperty.Comparator):
    def __gt__(self, other):
        "redefine the 'greater than' operation"

        return sql.and_(*[a>b for a, b in
                          zip(self.__clause_element__().clauses,
                              other.__composite_values__())])


# application of custom PropComparator subclasses

from sqlalchemy.orm import column_property, relationship, composite
from sqlalchemy import Column, String

class SomeMappedClass(Base):
    some_column = column_property(Column("some_column", String),
                        comparator_factory=MyColumnComparator)

    some_relationship = relationship(SomeOtherClass,
                        comparator_factory=MyRelationshipComparator)

    some_composite = composite(
            Column("a", String), Column("b", String),
            comparator_factory=MyCompositeComparator
        )

Note that for column-level operator redefinition, it’s usually simpler to define the operators at the Core level, using the TypeEngine.comparator_factory attribute. See Redefining and Creating New Operators for more detail.

See also:

ColumnProperty.Comparator

RelationshipProperty.Comparator

CompositeProperty.Comparator

ColumnOperators

Redefining and Creating New Operators

TypeEngine.comparator_factory

__eq__(other)
inherited from the __eq__() method of ColumnOperators

Implement the == operator.

In a column context, produces the clause a = b. If the target is None, produces a IS NULL.

__le__(other)
inherited from the __le__() method of ColumnOperators

Implement the <= operator.

In a column context, produces the clause a <= b.

__lt__(other)
inherited from the __lt__() method of ColumnOperators

Implement the < operator.

In a column context, produces the clause a < b.

__ne__(other)
inherited from the __ne__() method of ColumnOperators

Implement the != operator.

In a column context, produces the clause a != b. If the target is None, produces a IS NOT NULL.

adapt_to_entity(adapt_to_entity)

Return a copy of this PropComparator which will use the given AliasedInsp to produce corresponding expressions.

adapter

Produce a callable that adapts column expressions to suit an aliased version of this comparator.

any(criterion=None, **kwargs)

Return true if this collection contains any member that meets the given criterion.

The usual implementation of any() is RelationshipProperty.Comparator.any().

Parameters:
  • criterion – an optional ClauseElement formulated against the member class’ table or attributes.
  • **kwargs – key/value pairs corresponding to member class attribute names which will be compared via equality to the corresponding values.
asc()
inherited from the asc() method of ColumnOperators

Produce a asc() clause against the parent object.

between(cleft, cright, symmetric=False)
inherited from the between() method of ColumnOperators

Produce a between() clause against the parent object, given the lower and upper range.

collate(collation)
inherited from the collate() method of ColumnOperators

Produce a collate() clause against the parent object, given the collation string.

concat(other)
inherited from the concat() method of ColumnOperators

Implement the ‘concat’ operator.

In a column context, produces the clause a || b, or uses the concat() operator on MySQL.

contains(other, **kwargs)
inherited from the contains() method of ColumnOperators

Implement the ‘contains’ operator.

In a column context, produces the clause LIKE '%<other>%'

desc()
inherited from the desc() method of ColumnOperators

Produce a desc() clause against the parent object.

distinct()
inherited from the distinct() method of ColumnOperators

Produce a distinct() clause against the parent object.

endswith(other, **kwargs)
inherited from the endswith() method of ColumnOperators

Implement the ‘endswith’ operator.

In a column context, produces the clause LIKE '%<other>'

has(criterion=None, **kwargs)

Return true if this element references a member which meets the given criterion.

The usual implementation of has() is RelationshipProperty.Comparator.has().

Parameters:
  • criterion – an optional ClauseElement formulated against the member class’ table or attributes.
  • **kwargs – key/value pairs corresponding to member class attribute names which will be compared via equality to the corresponding values.
ilike(other, escape=None)
inherited from the ilike() method of ColumnOperators

Implement the ilike operator.

In a column context, produces the clause a ILIKE other.

E.g.:

select([sometable]).where(sometable.c.column.ilike("%foobar%"))
Parameters:
  • other – expression to be compared
  • escape

    optional escape character, renders the ESCAPE keyword, e.g.:

    somecolumn.ilike("foo/%bar", escape="/")
in_(other)
inherited from the in_() method of ColumnOperators

Implement the in operator.

In a column context, produces the clause a IN other. “other” may be a tuple/list of column expressions, or a select() construct.

is_(other)
inherited from the is_() method of ColumnOperators

Implement the IS operator.

Normally, IS is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS may be desirable if comparing to boolean values on certain platforms.

New in version 0.7.9.

isnot(other)
inherited from the isnot() method of ColumnOperators

Implement the IS NOT operator.

Normally, IS NOT is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS NOT may be desirable if comparing to boolean values on certain platforms.

New in version 0.7.9.

like(other, escape=None)
inherited from the like() method of ColumnOperators

Implement the like operator.

In a column context, produces the clause a LIKE other.

E.g.:

select([sometable]).where(sometable.c.column.like("%foobar%"))
Parameters:
  • other – expression to be compared
  • escape

    optional escape character, renders the ESCAPE keyword, e.g.:

    somecolumn.like("foo/%bar", escape="/")
match(other, **kwargs)
inherited from the match() method of ColumnOperators

Implements a database-specific ‘match’ operator.

match() attempts to resolve to a MATCH-like function or operator provided by the backend. Examples include:

  • Postgresql - renders x @@ to_tsquery(y)
  • MySQL - renders MATCH (x) AGAINST (y IN BOOLEAN MODE)
  • Oracle - renders CONTAINS(x, y)
  • other backends may provide special implementations; some backends such as SQLite have no support.
notilike(other, escape=None)
inherited from the notilike() method of ColumnOperators

implement the NOT ILIKE operator.

This is equivalent to using negation with ColumnOperators.ilike(), i.e. ~x.ilike(y).

New in version 0.8.

notin_(other)
inherited from the notin_() method of ColumnOperators

implement the NOT IN operator.

This is equivalent to using negation with ColumnOperators.in_(), i.e. ~x.in_(y).

New in version 0.8.

notlike(other, escape=None)
inherited from the notlike() method of ColumnOperators

implement the NOT LIKE operator.

This is equivalent to using negation with ColumnOperators.like(), i.e. ~x.like(y).

New in version 0.8.

nullsfirst()
inherited from the nullsfirst() method of ColumnOperators

Produce a nullsfirst() clause against the parent object.

nullslast()
inherited from the nullslast() method of ColumnOperators

Produce a nullslast() clause against the parent object.

of_type(class_)

Redefine this object in terms of a polymorphic subclass.

Returns a new PropComparator from which further criterion can be evaluated.

e.g.:

query.join(Company.employees.of_type(Engineer)).\
   filter(Engineer.name=='foo')
Parameters:class_ – a class or mapper indicating that criterion will be against this specific subclass.
op(opstring, precedence=0, is_comparison=False)
inherited from the op() method of Operators

produce a generic operator function.

e.g.:

somecolumn.op("*")(5)

produces:

somecolumn * 5

This function can also be used to make bitwise operators explicit. For example:

somecolumn.op('&')(0xff)

is a bitwise AND of the value in somecolumn.

Parameters:
  • operator – a string which will be output as the infix operator between this element and the expression passed to the generated function.
  • precedence

    precedence to apply to the operator, when parenthesizing expressions. A lower number will cause the expression to be parenthesized when applied against another operator with higher precedence. The default value of 0 is lower than all operators except for the comma (,) and AS operators. A value of 100 will be higher or equal to all operators, and -100 will be lower than or equal to all operators.

    New in version 0.8: - added the ‘precedence’ argument.

  • is_comparison

    if True, the operator will be considered as a “comparison” operator, that is which evaulates to a boolean true/false value, like ==, >, etc. This flag should be set so that ORM relationships can establish that the operator is a comparison operator when used in a custom join condition.

    New in version 0.9.2: - added the Operators.op.is_comparison flag.

operate(op, *other, **kwargs)
inherited from the operate() method of Operators

Operate on an argument.

This is the lowest level of operation, raises NotImplementedError by default.

Overriding this on a subclass can allow common behavior to be applied to all operations. For example, overriding ColumnOperators to apply func.lower() to the left and right side:

class MyComparator(ColumnOperators):
    def operate(self, op, other):
        return op(func.lower(self), func.lower(other))
Parameters:
  • op – Operator callable.
  • *other – the ‘other’ side of the operation. Will be a single scalar for most operations.
  • **kwargs – modifiers. These may be passed by special operators such as ColumnOperators.contains().
reverse_operate(op, other, **kwargs)
inherited from the reverse_operate() method of Operators

Reverse operate on an argument.

Usage is the same as operate().

startswith(other, **kwargs)
inherited from the startswith() method of ColumnOperators

Implement the startwith operator.

In a column context, produces the clause LIKE '<other>%'

class sqlalchemy.orm.properties.RelationshipProperty(argument, secondary=None, primaryjoin=None, secondaryjoin=None, foreign_keys=None, uselist=None, order_by=False, backref=None, back_populates=None, post_update=False, cascade=False, extension=None, viewonly=False, lazy=True, collection_class=None, passive_deletes=False, passive_updates=True, remote_side=None, enable_typechecks=True, join_depth=None, comparator_factory=None, single_parent=False, innerjoin=False, distinct_target_key=None, doc=None, active_history=False, cascade_backrefs=True, load_on_pending=False, strategy_class=None, _local_remote_pairs=None, query_class=None, info=None)

Bases: sqlalchemy.orm.interfaces.StrategizedProperty

Describes an object property that holds a single item or list of items that correspond to a related database table.

Public constructor is the orm.relationship() function.

See also:

Relationship Configuration

class Comparator(prop, parentmapper, adapt_to_entity=None, of_type=None)

Bases: sqlalchemy.orm.interfaces.PropComparator

Produce boolean, comparison, and other operators for RelationshipProperty attributes.

See the documentation for PropComparator for a brief overview of ORM level operator definition.

See also:

PropComparator

ColumnProperty.Comparator

ColumnOperators

Redefining and Creating New Operators

TypeEngine.comparator_factory

__eq__(other)

Implement the == operator.

In a many-to-one context, such as:

MyClass.some_prop == <some object>

this will typically produce a clause such as:

mytable.related_id == <some id>

Where <some id> is the primary key of the given object.

The == operator provides partial functionality for non- many-to-one comparisons:

  • Comparisons against collections are not supported. Use contains().
  • Compared to a scalar one-to-many, will produce a clause that compares the target columns in the parent to the given target.
  • Compared to a scalar many-to-many, an alias of the association table will be rendered as well, forming a natural join that is part of the main body of the query. This will not work for queries that go beyond simple AND conjunctions of comparisons, such as those which use OR. Use explicit joins, outerjoins, or has() for more comprehensive non-many-to-one scalar membership tests.
  • Comparisons against None given in a one-to-many or many-to-many context produce a NOT EXISTS clause.
__init__(prop, parentmapper, adapt_to_entity=None, of_type=None)

Construction of RelationshipProperty.Comparator is internal to the ORM’s attribute mechanics.

__le__(other)
inherited from the __le__() method of ColumnOperators

Implement the <= operator.

In a column context, produces the clause a <= b.

__lt__(other)
inherited from the __lt__() method of ColumnOperators

Implement the < operator.

In a column context, produces the clause a < b.

__ne__(other)

Implement the != operator.

In a many-to-one context, such as:

MyClass.some_prop != <some object>

This will typically produce a clause such as:

mytable.related_id != <some id>

Where <some id> is the primary key of the given object.

The != operator provides partial functionality for non- many-to-one comparisons:

  • Comparisons against collections are not supported. Use contains() in conjunction with not_().
  • Compared to a scalar one-to-many, will produce a clause that compares the target columns in the parent to the given target.
  • Compared to a scalar many-to-many, an alias of the association table will be rendered as well, forming a natural join that is part of the main body of the query. This will not work for queries that go beyond simple AND conjunctions of comparisons, such as those which use OR. Use explicit joins, outerjoins, or has() in conjunction with not_() for more comprehensive non-many-to-one scalar membership tests.
  • Comparisons against None given in a one-to-many or many-to-many context produce an EXISTS clause.
adapter
inherited from the adapter attribute of PropComparator

Produce a callable that adapts column expressions to suit an aliased version of this comparator.

any(criterion=None, **kwargs)

Produce an expression that tests a collection against particular criterion, using EXISTS.

An expression like:

session.query(MyClass).filter(
    MyClass.somereference.any(SomeRelated.x==2)
)

Will produce a query like:

SELECT * FROM my_table WHERE
EXISTS (SELECT 1 FROM related WHERE related.my_id=my_table.id
AND related.x=2)

Because any() uses a correlated subquery, its performance is not nearly as good when compared against large target tables as that of using a join.

any() is particularly useful for testing for empty collections:

session.query(MyClass).filter(
    ~MyClass.somereference.any()
)

will produce:

SELECT * FROM my_table WHERE
NOT EXISTS (SELECT 1 FROM related WHERE
related.my_id=my_table.id)

any() is only valid for collections, i.e. a relationship() that has uselist=True. For scalar references, use has().

asc()
inherited from the asc() method of ColumnOperators

Produce a asc() clause against the parent object.

between(cleft, cright, symmetric=False)
inherited from the between() method of ColumnOperators

Produce a between() clause against the parent object, given the lower and upper range.

collate(collation)
inherited from the collate() method of ColumnOperators

Produce a collate() clause against the parent object, given the collation string.

concat(other)
inherited from the concat() method of ColumnOperators

Implement the ‘concat’ operator.

In a column context, produces the clause a || b, or uses the concat() operator on MySQL.

contains(other, **kwargs)

Return a simple expression that tests a collection for containment of a particular item.

contains() is only valid for a collection, i.e. a relationship() that implements one-to-many or many-to-many with uselist=True.

When used in a simple one-to-many context, an expression like:

MyClass.contains(other)

Produces a clause like:

mytable.id == <some id>

Where <some id> is the value of the foreign key attribute on other which refers to the primary key of its parent object. From this it follows that contains() is very useful when used with simple one-to-many operations.

For many-to-many operations, the behavior of contains() has more caveats. The association table will be rendered in the statement, producing an “implicit” join, that is, includes multiple tables in the FROM clause which are equated in the WHERE clause:

query(MyClass).filter(MyClass.contains(other))

Produces a query like:

SELECT * FROM my_table, my_association_table AS
my_association_table_1 WHERE
my_table.id = my_association_table_1.parent_id
AND my_association_table_1.child_id = <some id>

Where <some id> would be the primary key of other. From the above, it is clear that contains() will not work with many-to-many collections when used in queries that move beyond simple AND conjunctions, such as multiple contains() expressions joined by OR. In such cases subqueries or explicit “outer joins” will need to be used instead. See any() for a less-performant alternative using EXISTS, or refer to Query.outerjoin() as well as Querying with Joins for more details on constructing outer joins.

desc()
inherited from the desc() method of ColumnOperators

Produce a desc() clause against the parent object.

distinct()
inherited from the distinct() method of ColumnOperators

Produce a distinct() clause against the parent object.

endswith(other, **kwargs)
inherited from the endswith() method of ColumnOperators

Implement the ‘endswith’ operator.

In a column context, produces the clause LIKE '%<other>'

has(criterion=None, **kwargs)

Produce an expression that tests a scalar reference against particular criterion, using EXISTS.

An expression like:

session.query(MyClass).filter(
    MyClass.somereference.has(SomeRelated.x==2)
)

Will produce a query like:

SELECT * FROM my_table WHERE
EXISTS (SELECT 1 FROM related WHERE
related.id==my_table.related_id AND related.x=2)

Because has() uses a correlated subquery, its performance is not nearly as good when compared against large target tables as that of using a join.

has() is only valid for scalar references, i.e. a relationship() that has uselist=False. For collection references, use any().

ilike(other, escape=None)
inherited from the ilike() method of ColumnOperators

Implement the ilike operator.

In a column context, produces the clause a ILIKE other.

E.g.:

select([sometable]).where(sometable.c.column.ilike("%foobar%"))
Parameters:
  • other – expression to be compared
  • escape

    optional escape character, renders the ESCAPE keyword, e.g.:

    somecolumn.ilike("foo/%bar", escape="/")
in_(other)

Produce an IN clause - this is not implemented for relationship()-based attributes at this time.

is_(other)
inherited from the is_() method of ColumnOperators

Implement the IS operator.

Normally, IS is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS may be desirable if comparing to boolean values on certain platforms.

New in version 0.7.9.

isnot(other)
inherited from the isnot() method of ColumnOperators

Implement the IS NOT operator.

Normally, IS NOT is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS NOT may be desirable if comparing to boolean values on certain platforms.

New in version 0.7.9.

like(other, escape=None)
inherited from the like() method of ColumnOperators

Implement the like operator.

In a column context, produces the clause a LIKE other.

E.g.:

select([sometable]).where(sometable.c.column.like("%foobar%"))
Parameters:
  • other – expression to be compared
  • escape

    optional escape character, renders the ESCAPE keyword, e.g.:

    somecolumn.like("foo/%bar", escape="/")
mapper

The target Mapper referred to by this RelationshipProperty.Comparator.

This is the “target” or “remote” side of the relationship().

match(other, **kwargs)
inherited from the match() method of ColumnOperators

Implements a database-specific ‘match’ operator.

match() attempts to resolve to a MATCH-like function or operator provided by the backend. Examples include:

  • Postgresql - renders x @@ to_tsquery(y)
  • MySQL - renders MATCH (x) AGAINST (y IN BOOLEAN MODE)
  • Oracle - renders CONTAINS(x, y)
  • other backends may provide special implementations; some backends such as SQLite have no support.
notilike(other, escape=None)
inherited from the notilike() method of ColumnOperators

implement the NOT ILIKE operator.

This is equivalent to using negation with ColumnOperators.ilike(), i.e. ~x.ilike(y).

New in version 0.8.

notin_(other)
inherited from the notin_() method of ColumnOperators

implement the NOT IN operator.

This is equivalent to using negation with ColumnOperators.in_(), i.e. ~x.in_(y).

New in version 0.8.

notlike(other, escape=None)
inherited from the notlike() method of ColumnOperators

implement the NOT LIKE operator.

This is equivalent to using negation with ColumnOperators.like(), i.e. ~x.like(y).

New in version 0.8.

nullsfirst()
inherited from the nullsfirst() method of ColumnOperators

Produce a nullsfirst() clause against the parent object.

nullslast()
inherited from the nullslast() method of ColumnOperators

Produce a nullslast() clause against the parent object.

of_type(cls)

Produce a construct that represents a particular ‘subtype’ of attribute for the parent class.

Currently this is usable in conjunction with Query.join() and Query.outerjoin().

op(opstring, precedence=0, is_comparison=False)
inherited from the op() method of Operators

produce a generic operator function.

e.g.:

somecolumn.op("*")(5)

produces:

somecolumn * 5

This function can also be used to make bitwise operators explicit. For example:

somecolumn.op('&')(0xff)

is a bitwise AND of the value in somecolumn.

Parameters:
  • operator – a string which will be output as the infix operator between this element and the expression passed to the generated function.
  • precedence

    precedence to apply to the operator, when parenthesizing expressions. A lower number will cause the expression to be parenthesized when applied against another operator with higher precedence. The default value of 0 is lower than all operators except for the comma (,) and AS operators. A value of 100 will be higher or equal to all operators, and -100 will be lower than or equal to all operators.

    New in version 0.8: - added the ‘precedence’ argument.

  • is_comparison

    if True, the operator will be considered as a “comparison” operator, that is which evaulates to a boolean true/false value, like ==, >, etc. This flag should be set so that ORM relationships can establish that the operator is a comparison operator when used in a custom join condition.

    New in version 0.9.2: - added the Operators.op.is_comparison flag.

operate(op, *other, **kwargs)
inherited from the operate() method of Operators

Operate on an argument.

This is the lowest level of operation, raises NotImplementedError by default.

Overriding this on a subclass can allow common behavior to be applied to all operations. For example, overriding ColumnOperators to apply func.lower() to the left and right side:

class MyComparator(ColumnOperators):
    def operate(self, op, other):
        return op(func.lower(self), func.lower(other))
Parameters:
  • op – Operator callable.
  • *other – the ‘other’ side of the operation. Will be a single scalar for most operations.
  • **kwargs – modifiers. These may be passed by special operators such as ColumnOperators.contains().
reverse_operate(op, other, **kwargs)
inherited from the reverse_operate() method of Operators

Reverse operate on an argument.

Usage is the same as operate().

startswith(other, **kwargs)
inherited from the startswith() method of ColumnOperators

Implement the startwith operator.

In a column context, produces the clause LIKE '<other>%'

RelationshipProperty.__init__(argument, secondary=None, primaryjoin=None, secondaryjoin=None, foreign_keys=None, uselist=None, order_by=False, backref=None, back_populates=None, post_update=False, cascade=False, extension=None, viewonly=False, lazy=True, collection_class=None, passive_deletes=False, passive_updates=True, remote_side=None, enable_typechecks=True, join_depth=None, comparator_factory=None, single_parent=False, innerjoin=False, distinct_target_key=None, doc=None, active_history=False, cascade_backrefs=True, load_on_pending=False, strategy_class=None, _local_remote_pairs=None, query_class=None, info=None)

Construct a new RelationshipProperty object.

This constructor is mirrored as a public API function; see relationship() for a full usage and argument description.

RelationshipProperty.cascade

Return the current cascade setting for this RelationshipProperty.

RelationshipProperty.class_attribute
inherited from the class_attribute attribute of MapperProperty

Return the class-bound descriptor corresponding to this MapperProperty.

This is basically a getattr() call:

return getattr(self.parent.class_, self.key)

I.e. if this MapperProperty were named addresses, and the class to which it is mapped is User, this sequence is possible:

>>> from sqlalchemy import inspect
>>> mapper = inspect(User)
>>> addresses_property = mapper.attrs.addresses
>>> addresses_property.class_attribute is User.addresses
True
>>> User.addresses.property is addresses_property
True
RelationshipProperty.extension_type = symbol('NOT_EXTENSION')
RelationshipProperty.info
inherited from the info attribute of MapperProperty

Info dictionary associated with the object, allowing user-defined data to be associated with this MapperProperty.

The dictionary is generated when first accessed. Alternatively, it can be specified as a constructor argument to the column_property(), relationship(), or composite() functions.

New in version 0.8: Added support for .info to all MapperProperty subclasses.

RelationshipProperty.init()
inherited from the init() method of MapperProperty

Called after all mappers are created to assemble relationships between mappers and perform other post-mapper-creation initialization steps.

RelationshipProperty.is_primary()
inherited from the is_primary() method of MapperProperty

Return True if this MapperProperty‘s mapper is the primary mapper for its class.

This flag is used to indicate that the MapperProperty can define attribute instrumentation for the class at the class level (as opposed to the individual instance level).

RelationshipProperty.mapper

Return the targeted Mapper for this RelationshipProperty.

This is a lazy-initializing static attribute.

RelationshipProperty.table

Return the selectable linked to this RelationshipProperty object’s target Mapper.

Deprecated since version 0.7: Use .target

class sqlalchemy.orm.descriptor_props.SynonymProperty(name, map_column=None, descriptor=None, comparator_factory=None, doc=None)

Bases: sqlalchemy.orm.descriptor_props.DescriptorProperty

__init__(name, map_column=None, descriptor=None, comparator_factory=None, doc=None)

Construct a new SynonymProperty object.

This constructor is mirrored as a public API function; see synonym() for a full usage and argument description.

cascade_iterator(type_, state, visited_instances=None, halt_on=None)
inherited from the cascade_iterator() method of MapperProperty

Iterate through instances related to the given instance for a particular ‘cascade’, starting with this MapperProperty.

Return an iterator3-tuples (instance, mapper, state).

Note that the ‘cascade’ collection on this MapperProperty is checked first for the given type before cascade_iterator is called.

See PropertyLoader for the related instance implementation.

class_attribute
inherited from the class_attribute attribute of MapperProperty

Return the class-bound descriptor corresponding to this MapperProperty.

This is basically a getattr() call:

return getattr(self.parent.class_, self.key)

I.e. if this MapperProperty were named addresses, and the class to which it is mapped is User, this sequence is possible:

>>> from sqlalchemy import inspect
>>> mapper = inspect(User)
>>> addresses_property = mapper.attrs.addresses
>>> addresses_property.class_attribute is User.addresses
True
>>> User.addresses.property is addresses_property
True
compare(operator, value, **kw)
inherited from the compare() method of MapperProperty

Return a compare operation for the columns represented by this MapperProperty to the given value, which may be a column value or an instance. ‘operator’ is an operator from the operators module, or from sql.Comparator.

By default uses the PropComparator attached to this MapperProperty under the attribute name “comparator”.

create_row_processor(context, path, mapper, row, adapter)
inherited from the create_row_processor() method of MapperProperty

Return a 3-tuple consisting of three row processing functions.

do_init()
inherited from the do_init() method of MapperProperty

Perform subclass-specific initialization post-mapper-creation steps.

This is a template method called by the MapperProperty object’s init() method.

extension_type = symbol('NOT_EXTENSION')
info
inherited from the info attribute of MapperProperty

Info dictionary associated with the object, allowing user-defined data to be associated with this MapperProperty.

The dictionary is generated when first accessed. Alternatively, it can be specified as a constructor argument to the column_property(), relationship(), or composite() functions.

New in version 0.8: Added support for .info to all MapperProperty subclasses.

init()
inherited from the init() method of MapperProperty

Called after all mappers are created to assemble relationships between mappers and perform other post-mapper-creation initialization steps.

is_primary()
inherited from the is_primary() method of MapperProperty

Return True if this MapperProperty‘s mapper is the primary mapper for its class.

This flag is used to indicate that the MapperProperty can define attribute instrumentation for the class at the class level (as opposed to the individual instance level).

merge(session, source_state, source_dict, dest_state, dest_dict, load, _recursive)
inherited from the merge() method of MapperProperty

Merge the attribute represented by this MapperProperty from source to destination object

post_instrument_class(mapper)
inherited from the post_instrument_class() method of MapperProperty

Perform instrumentation adjustments that need to occur after init() has completed.

setup(context, entity, path, adapter, **kwargs)
inherited from the setup() method of MapperProperty

Called by Query for the purposes of constructing a SQL statement.

Each MapperProperty associated with the target mapper processes the statement referenced by the query context, adding columns and/or criterion as appropriate.

class sqlalchemy.orm.query.QueryContext(query)
class sqlalchemy.orm.attributes.QueryableAttribute(class_, key, impl=None, comparator=None, parententity=None, of_type=None)

Bases: sqlalchemy.orm.base._MappedAttribute, sqlalchemy.orm.base._InspectionAttr, sqlalchemy.orm.interfaces.PropComparator

Base class for descriptor objects that intercept attribute events on behalf of a MapperProperty object. The actual MapperProperty is accessible via the QueryableAttribute.property attribute.

__eq__(other)
inherited from the __eq__() method of ColumnOperators

Implement the == operator.

In a column context, produces the clause a = b. If the target is None, produces a IS NULL.

__le__(other)
inherited from the __le__() method of ColumnOperators

Implement the <= operator.

In a column context, produces the clause a <= b.

__lt__(other)
inherited from the __lt__() method of ColumnOperators

Implement the < operator.

In a column context, produces the clause a < b.

__ne__(other)
inherited from the __ne__() method of ColumnOperators

Implement the != operator.

In a column context, produces the clause a != b. If the target is None, produces a IS NOT NULL.

adapter
inherited from the adapter attribute of PropComparator

Produce a callable that adapts column expressions to suit an aliased version of this comparator.

any(criterion=None, **kwargs)
inherited from the any() method of PropComparator

Return true if this collection contains any member that meets the given criterion.

The usual implementation of any() is RelationshipProperty.Comparator.any().

Parameters:
  • criterion – an optional ClauseElement formulated against the member class’ table or attributes.
  • **kwargs – key/value pairs corresponding to member class attribute names which will be compared via equality to the corresponding values.
asc()
inherited from the asc() method of ColumnOperators

Produce a asc() clause against the parent object.

between(cleft, cright, symmetric=False)
inherited from the between() method of ColumnOperators

Produce a between() clause against the parent object, given the lower and upper range.

collate(collation)
inherited from the collate() method of ColumnOperators

Produce a collate() clause against the parent object, given the collation string.

concat(other)
inherited from the concat() method of ColumnOperators

Implement the ‘concat’ operator.

In a column context, produces the clause a || b, or uses the concat() operator on MySQL.

contains(other, **kwargs)
inherited from the contains() method of ColumnOperators

Implement the ‘contains’ operator.

In a column context, produces the clause LIKE '%<other>%'

desc()
inherited from the desc() method of ColumnOperators

Produce a desc() clause against the parent object.

distinct()
inherited from the distinct() method of ColumnOperators

Produce a distinct() clause against the parent object.

endswith(other, **kwargs)
inherited from the endswith() method of ColumnOperators

Implement the ‘endswith’ operator.

In a column context, produces the clause LIKE '%<other>'

extension_type = symbol('NOT_EXTENSION')
has(criterion=None, **kwargs)
inherited from the has() method of PropComparator

Return true if this element references a member which meets the given criterion.

The usual implementation of has() is RelationshipProperty.Comparator.has().

Parameters:
  • criterion – an optional ClauseElement formulated against the member class’ table or attributes.
  • **kwargs – key/value pairs corresponding to member class attribute names which will be compared via equality to the corresponding values.
ilike(other, escape=None)
inherited from the ilike() method of ColumnOperators

Implement the ilike operator.

In a column context, produces the clause a ILIKE other.

E.g.:

select([sometable]).where(sometable.c.column.ilike("%foobar%"))
Parameters:
  • other – expression to be compared
  • escape

    optional escape character, renders the ESCAPE keyword, e.g.:

    somecolumn.ilike("foo/%bar", escape="/")
in_(other)
inherited from the in_() method of ColumnOperators

Implement the in operator.

In a column context, produces the clause a IN other. “other” may be a tuple/list of column expressions, or a select() construct.

info

Return the ‘info’ dictionary for the underlying SQL element.

The behavior here is as follows:

New in version 0.8.0.

is_(other)
inherited from the is_() method of ColumnOperators

Implement the IS operator.

Normally, IS is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS may be desirable if comparing to boolean values on certain platforms.

New in version 0.7.9.

isnot(other)
inherited from the isnot() method of ColumnOperators

Implement the IS NOT operator.

Normally, IS NOT is generated automatically when comparing to a value of None, which resolves to NULL. However, explicit usage of IS NOT may be desirable if comparing to boolean values on certain platforms.

New in version 0.7.9.

like(other, escape=None)
inherited from the like() method of ColumnOperators

Implement the like operator.

In a column context, produces the clause a LIKE other.

E.g.:

select([sometable]).where(sometable.c.column.like("%foobar%"))
Parameters:
  • other – expression to be compared
  • escape

    optional escape character, renders the ESCAPE keyword, e.g.:

    somecolumn.like("foo/%bar", escape="/")
match(other, **kwargs)
inherited from the match() method of ColumnOperators

Implements a database-specific ‘match’ operator.

match() attempts to resolve to a MATCH-like function or operator provided by the backend. Examples include:

  • Postgresql - renders x @@ to_tsquery(y)
  • MySQL - renders MATCH (x) AGAINST (y IN BOOLEAN MODE)
  • Oracle - renders CONTAINS(x, y)
  • other backends may provide special implementations; some backends such as SQLite have no support.
notilike(other, escape=None)
inherited from the notilike() method of ColumnOperators

implement the NOT ILIKE operator.

This is equivalent to using negation with ColumnOperators.ilike(), i.e. ~x.ilike(y).

New in version 0.8.

notin_(other)
inherited from the notin_() method of ColumnOperators

implement the NOT IN operator.

This is equivalent to using negation with ColumnOperators.in_(), i.e. ~x.in_(y).

New in version 0.8.

notlike(other, escape=None)
inherited from the notlike() method of ColumnOperators

implement the NOT LIKE operator.

This is equivalent to using negation with ColumnOperators.like(), i.e. ~x.like(y).

New in version 0.8.

nullsfirst()
inherited from the nullsfirst() method of ColumnOperators

Produce a nullsfirst() clause against the parent object.

nullslast()
inherited from the nullslast() method of ColumnOperators

Produce a nullslast() clause against the parent object.

op(opstring, precedence=0, is_comparison=False)
inherited from the op() method of Operators

produce a generic operator function.

e.g.:

somecolumn.op("*")(5)

produces:

somecolumn * 5

This function can also be used to make bitwise operators explicit. For example:

somecolumn.op('&')(0xff)

is a bitwise AND of the value in somecolumn.

Parameters:
  • operator – a string which will be output as the infix operator between this element and the expression passed to the generated function.
  • precedence

    precedence to apply to the operator, when parenthesizing expressions. A lower number will cause the expression to be parenthesized when applied against another operator with higher precedence. The default value of 0 is lower than all operators except for the comma (,) and AS operators. A value of 100 will be higher or equal to all operators, and -100 will be lower than or equal to all operators.

    New in version 0.8: - added the ‘precedence’ argument.

  • is_comparison

    if True, the operator will be considered as a “comparison” operator, that is which evaulates to a boolean true/false value, like ==, >, etc. This flag should be set so that ORM relationships can establish that the operator is a comparison operator when used in a custom join condition.

    New in version 0.9.2: - added the Operators.op.is_comparison flag.

parent

Return an inspection instance representing the parent.

This will be either an instance of Mapper or AliasedInsp, depending upon the nature of the parent entity which this attribute is associated with.

property

Return the MapperProperty associated with this QueryableAttribute.

Return values here will commonly be instances of ColumnProperty or RelationshipProperty.

startswith(other, **kwargs)
inherited from the startswith() method of ColumnOperators

Implement the startwith operator.

In a column context, produces the clause LIKE '<other>%'

class sqlalchemy.orm.session.UOWTransaction(session)
filter_states_for_dep(dep, states)

Filter the given list of InstanceStates to those relevant to the given DependencyProcessor.

finalize_flush_changes()

mark processed objects as clean / deleted after a successful flush().

this method is called within the flush() method after the execute() method has succeeded and the transaction has been committed.

get_attribute_history(state, key, passive=symbol('PASSIVE_NO_INITIALIZE'))

facade to attributes.get_state_history(), including caching of results.

is_deleted(state)

return true if the given state is marked as deleted within this uowtransaction.

remove_state_actions(state)

remove pending actions for a state from the uowtransaction.