实体框架4：添加和保存实体的最佳方法是什么？

Question

I have a BaseRepository class that is used by all repositories to save entities (new or updated):

public abstract class BaseRepository
{
    protected void Add<T>(T source, CliCEntities context, bool isNew, EntityState state) where T : class
    {
        if (isNew)
        {
            context.CreateObjectSet<T>().AddObject(source);
        }
        else
        {
            if (state == EntityState.Detached)
            {
                context.CreateObjectSet<T>().Attach(source);
            }
        }
    }

    protected void Save(MyEntities context)
    {
        context.SaveChanges();
    }
}

It's called like this:

public class MyEntityRepository : BaseRepository
{
    public void Add(MyEntity source, MyEntities context)
    {
        base.Add(source, context, source.ID == Guid.Empty, source.EntityState);
    }

    public void Save(MyEntities context) {
        base.Save(context);
    }
}

The issue

When the base.Save() is called, there's no difference to the data, EntityState is unchanged. I assume this is because the load was on a different Context instance, so the current Context doesn't know about any changes.

How can I change the above code so that my source instance has EntityState Modified (so that it would work)?

Answer 1

I found a solution:

protected void Add<T>(T source, CliCEntities context, bool isNew, EntityState state) where T : class
{
    if (isNew)
    {
        context.CreateObjectSet<T>().AddObject(source);
    }
    else
    {
        if (state == EntityState.Detached)
        {
            context.CreateObjectSet<T>().Attach(source);

            context.ObjectStateManager.ChangeObjectState(source, EntityState.Modified);
        }
    }
}

The big difference is this:

context.ObjectStateManager.ChangeObjectState(source, EntityState.Modified);

That way I can change the EntityState of the source object, so it's actually updated.