Entity State in Entity Framework

In Entity Framework, the EntityState is an enumeration that represents the state of an entity being tracked by the DbContext. It is used to determine what actions need to be taken when saving changes to the database.

The EntityState enumeration consists of the following values:

1. Added: Indicates that the entity is being tracked by the context and is scheduled to be inserted into the database when SaveChanges is called.
2. Unchanged: Indicates that the entity is being tracked by the context and its state has not changed since it was attached to the context or since the last call to SaveChanges.
3. Modified: Indicates that the entity is being tracked by the context and some or all of its properties have been modified. When SaveChanges is called, the context will generate an update statement for the entity in the database.
4. Deleted: Indicates that the entity is being tracked by the context and is scheduled to be deleted from the database when SaveChanges is called.
5. Detached: Indicates that the entity is not being tracked by the context. This is the initial state of an entity before it is attached to a context or after it has been removed from the context.

You can access and modify the EntityState of an entity using the Entry method of the DbContext. For example:

var entity = dbContext.Set<MyEntity>().Find(id);
dbContext.Entry(entity).State = EntityState.Modified;
dbContext.SaveChanges();

This code snippet retrieves an entity from the database, sets its EntityState to Modified, and then saves the changes to the database.

The EntityState is important for Entity Framework's change tracking mechanism. It helps the framework determine which entities need to be inserted, updated, or deleted when changes are saved to the database.