Entity Framework 4.1 DbSet Reload

Question

I\'m using a single instance of DbContext scenario to shadow entire copy of the database locally in a WPF app. I\'ve heard this is bad practice, but my database

Answer 1

DbContexts are supposed to live short time, Consider after saving changes disposing it and reloading all from the start. Have 2 sets of objects.. one from db and another for binding.

Answer 2

This is not the way you are supposed to use DbContext, and because of that it is almost impossible to reload the data. Keeping a single context around for a long time is incorrect usage. The link will also answer why your tracked entities are not updated.

You can selectively reload a single entity by calling Reload on DbEntityEntry:

context.Entry(entity).Reload();

You can also revert back to ObjectContext and use ObjectQuery with MergeOption.OverrideChanges, or use Refresh for a collection of entities with RefreshMode.StoreWins.

All these approaches suffers some problems:

• If the record is deleted in the database, it will not be removed from the context.
• Changes in relations are not always refreshed.

The only correct way to get fresh data is Dispose the context, create a new one and load everything from scratch - and you are doing this anyway.

Answer 3

With Entity Framework 4.1, the recommendation for WPF data binding has changed to use .Local and a persistent DbContext.

http://blogs.msdn.com/b/efdesign/archive/2010/09/08/data-binding-with-dbcontext.aspx

It's, of course, possible to dispose of it whenever you need to, but it can negatively impact the UI if you do.

Here's another method, but I'm not sure that it takes EF4.1's features into account:

http://msdn.microsoft.com/en-us/library/cc716735.aspx

Answer 4

Please use using() for CRUD.It will automatically reload the updated data.

using (myDbContext context = new myDbContext())
{

}

Best Regards, Thet Tin Oo