Mapper Configuration

This section describes a variety of configurational patterns that are usable with mappers. It assumes you’ve worked through Object Relational Tutorial (1.x API) and know how to construct and use rudimentary mappers and relationships.

• Mapping Python Classes
  • Declarative Mapping
  • Imperative (a.k.a. Classical) Mappings
    • Imperative Mapping with Dataclasses and Attrs
  • Mapper Configuration Overview
    • The class to be mapped
    • The table, or other from clause object
    • The properties dictionary
    • Other mapper configuration parameters
  • Mapped Class Behavior
    • Default Constructor
    • Runtime Introspection of Mapped classes and Mappers
    • Mapper Inspection Features
• Mapping Classes with Declarative
  • Declarative Mapping Styles
    • Using a Generated Base Class
    • Creating an Explicit Base Non-Dynamically (for use with mypy, similar)
    • Declarative Mapping using a Decorator (no declarative base)
    • Declarative Mapping with Dataclasses and Attrs
  • Table Configuration with Declarative
    • Declarative Table
    • Declarative with Imperative Table (a.k.a. Hybrid Declarative)
    • Mapping Declaratively with Reflected Tables
  • Mapper Configuration with Declarative
    • Defining Mapped Properties with Declarative
    • Mapper Configuration Options with Declarative
    • Other Declarative Mapping Directives
  • Composing Mapped Hierarchies with Mixins
    • Augmenting the Base
    • Mixing in Columns
    • Mixing in Relationships
    • Mixing in deferred(), column_property(), and other MapperProperty classes
    • Mixing in Association Proxy and Other Attributes
    • Controlling table inheritance with mixins
    • Mixing in Columns in Inheritance Scenarios
    • Combining Table/Mapper Arguments from Multiple Mixins
    • Creating Indexes with Mixins
• Mapping Columns and Expressions
  • Mapping Table Columns
    • Naming Columns Distinctly from Attribute Names
    • Automating Column Naming Schemes from Reflected Tables
    • Naming All Columns with a Prefix
    • Using column_property for column level options
    • Mapping a Subset of Table Columns
  • SQL Expressions as Mapped Attributes
    • Using a Hybrid
    • Using column_property
    • Using a plain descriptor
    • Query-time SQL expressions as mapped attributes
  • Changing Attribute Behavior
    • Simple Validators
    • Using Custom Datatypes at the Core Level
    • Using Descriptors and Hybrids
    • Synonyms
    • Operator Customization
  • Composite Column Types
    • Tracking In-Place Mutations on Composites
    • Redefining Comparison Operations for Composites
    • Nesting Composites
• Mapping Class Inheritance Hierarchies
  • Joined Table Inheritance
    • Relationships with Joined Inheritance
    • Loading Joined Inheritance Mappings
  • Single Table Inheritance
    • Resolving Column Conflicts
    • Relationships with Single Table Inheritance
    • Loading Single Inheritance Mappings
  • Concrete Table Inheritance
    • Concrete Polymorphic Loading Configuration
    • Abstract Concrete Classes
    • Classical and Semi-Classical Concrete Polymorphic Configuration
    • Relationships with Concrete Inheritance
    • Loading Concrete Inheritance Mappings
• Non-Traditional Mappings
  • Mapping a Class against Multiple Tables
  • Mapping a Class against Arbitrary Subqueries
  • Multiple Mappers for One Class
• Configuring a Version Counter
  • Simple Version Counting
  • Custom Version Counters / Types
  • Server Side Version Counters
  • Programmatic or Conditional Version Counters
• Class Mapping API