Release: 1.4.51 | Release Date: January 2, 2024

# SQLAlchemy 1.4 Documentation

# Events and Internals

The SQLAlchemy ORM as well as Core are extended generally through the use of event hooks. Be sure to review the use of the event system in general at Events.

- ORM Events
  - Session Events
  - Mapper Events
  - Instance Events
  - Attribute Events
  - Query Events
  - Instrumentation Events
- ORM Internals
  - `AttributeState`
  - `CascadeOptions`
  - `ClassManager`
  - `ColumnProperty`
  - `ColumnProperty.Comparator.expressions`
  - `CompositeProperty`
  - `AttributeEvent`
  - `IdentityMap`
  - `InspectionAttr`
  - `InspectionAttrInfo`
  - `InstanceState`
  - `InstrumentedAttribute`
  - `MANYTOONE`
  - `MANYTOMANY`
  - `Mapped`
  - `MapperProperty`
  - `NOT_EXTENSION`
  - `merge_result()`
  - `merge_frozen_result()`
  - `ONETOMANY`
  - `PropComparator`
  - `RelationshipProperty`
  - `SynonymProperty`
  - `QueryContext`
  - `QueryableAttribute`
  - `UOWTransaction`
- ORM Exceptions
  - `ConcurrentModificationError`
  - `DetachedInstanceError`
  - `FlushError`
  - `LoaderStrategyException`
  - `NO_STATE`
  - `ObjectDeletedError`
  - `ObjectDereferencedError`
  - `StaleDataError`
  - `UnmappedClassError`
  - `UnmappedColumnError`
  - `UnmappedError`
  - `UnmappedInstanceError`