Relationship Configuration

This section describes the relationship() function and in depth discussion of its usage. For an introduction to relationships, start with the Object Relational Tutorial (1.x API) and head into Working with ORM Related Objects.

• Basic Relationship Patterns
  • One To Many
    • Configuring Delete Behavior for One to Many
  • Many To One
  • One To One
  • Many To Many
    • Deleting Rows from the Many to Many Table
  • Association Object
• Late-Evaluation of Relationship Arguments
  • Late-Evaluation for a many-to-many relationship
• Adjacency List Relationships
  • Composite Adjacency Lists
  • Self-Referential Query Strategies
  • Configuring Self-Referential Eager Loading
• Configuring how Relationship Joins
  • Handling Multiple Join Paths
  • Specifying Alternate Join Conditions
  • Creating Custom Foreign Conditions
  • Using custom operators in join conditions
  • Custom operators based on SQL functions
  • Overlapping Foreign Keys
  • Non-relational Comparisons / Materialized Path
  • Self-Referential Many-to-Many Relationship
  • Composite “Secondary” Joins
  • Relationship to Aliased Class
    • Using the AliasedClass target in Queries
  • Row-Limited Relationships with Window Functions
  • Building Query-Enabled Properties
• Collection Configuration and Techniques
  • Working with Large Collections
    • Dynamic Relationship Loaders
    • Setting Noload, RaiseLoad
    • Using Passive Deletes
  • Customizing Collection Access
    • Dictionary Collections
  • Custom Collection Implementations
    • Annotating Custom Collections via Decorators
    • Custom Dictionary-Based Collections
    • Instrumentation and Custom Types
  • Collection Internals
    • bulk_replace()
    • collection_adapter
    • CollectionAdapter
    • InstrumentedDict
    • InstrumentedList
    • InstrumentedSet
    • prepare_instrumentation()
• Special Relationship Persistence Patterns
  • Rows that point to themselves / Mutually Dependent Rows
  • Mutable Primary Keys / Update Cascades
    • Simulating limited ON UPDATE CASCADE without foreign key support
• Using the legacy ‘backref’ relationship parameter
  • Backref Default Arguments
  • Specifying Backref Arguments
• Relationships API
  • relationship()
  • backref()
  • relation()
  • dynamic_loader()
  • foreign()
  • remote()