change-tracking

name	change-tracking
description	Implementation details for EF Core change tracking. Use when changing InternalEntityEntry, ChangeDetector, SnapshotFactoryFactory, or related entity state, snapshot, or property accessor code.
user-invocable	false

Change Tracking

Manages entity states and detects changes for SaveChanges().

Core Components

• StateManager — central engine, identity maps, tracks all entities
• InternalEntityEntry — per-entity state, property flags, snapshots
• SnapshotFactoryFactory subclasses build snapshot factories for change detection
• PropertyAccessorsFactory, ClrPropertyGetterFactory and ClrPropertySetterFactory compile property accessors for efficient snapshotting and change detection
  • Ordinals in indices parameter specify element at each complex collection depth

Testing

Unit tests: test/EFCore.Tests/ChangeTracking/. Functional tests: test/EFCore.Specification.Tests/GraphUpdates/.

Common Pitfalls

Pitfall	Solution
There is a failure when there is shared identity entry (Added and Deleted)	Add code that checks SharedIdentityEntry

Validation

• DetectChanges() identifies modified properties via snapshot comparison
• Setting original values marks properties as modified or unchanged based on comparison with current values