Life Cycle of Entity

During entity’s lifetime, each entity has an entity state based on operation performed on it via Context (ObjectContext). The entity state is an enum of type System.Data.EntityState that declares the following values:

1. Added
2. Deleted
3. Modified
4. Unchanged
5. Detached

The Context not only holds the reference to all the objects retrieved from the database but also it holds the entity states and maintains modifications to the properties of the entity. This feature is known as Change Tracking.

The change in entity state from the Unchanged to the Modified state is the only state that’s automatically handled by the context. All other changes must be made explicitly using proper methods of ObjectContext:

Sr.	ObjectContext Methods	Description	EntityState
1	AddObject	Adds an entity to the context	Added
2	Attach	Attaches an entity to the context	Unchanged
3	ApplyCurrentValues	Replace currently attached entity’s scalar value with the property values of detached entity.	Modified
4	ApplyOriginalValues	It applies original database values to attached entity’s properties.	Unchanged
5	DeleteObject	Delete the object from context.	Deleted
6	AcceptAllChanges	pushes the current values of every attached entity into the original values.	Unchanged
7	ChangeState or ChangeObjectState	Change an entity from one state to another without any restrictions (except for Detached)	Based on passed state
8	Detach	Removes an entity from the context.	Detached