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Entity Framework - Why explicitly set entity state to modified?

The official documentation says to modify an entity I retrieve a DbEntityEntry object and either work with the property functions or I set its state to modified. It uses the following example

Department dpt = context.Departments.FirstOrDefault();
DbEntityEntry entry = context.Entry(dpt);
entry.State = EntityState.Modified;

I don't understand the purpose of the 2nd and 3rd statement. If I ask the framework for an entity like the 1st statement does and then modify the POCO as in

dpt.Name = "Blah"

If I then ask EF to SaveChanges(), the entity has a status of MODIFIED (I'm guessing via snapshot tracking, this isn't a proxy) and the changes are persisted without the need to manually set the state. Am I missing something here?

Solution

  • In your scenario you indeed don't have to set the state. It is purpose of change tracking to find that you have changed a value on attached entity and put it to modified state. Setting state manually is important in case of detached entities (entities loaded without change tracking or created outside of the current context).