Is there a DbSet<TEntity>.Local equivalent in Entity Framework 7?

问题

I need an

ObservableCollection<TEntity>

in EF7,

DbSet<TEntity>.Local

doesn't seem to exist;

Is there any workaround?

回答1:

Current version of EntityFramework (RC1-final) has no DbSet.Local feature. But! You can achieve something similar with current extension method:

public static class Extensions
{
    public static ObservableCollection<TEntity> GetLocal<TEntity>(this DbSet<TEntity> set)
        where TEntity : class
    {
        var context = set.GetService<DbContext>();
        var data = context.ChangeTracker.Entries<TEntity>().Select(e => e.Entity);
        var collection = new ObservableCollection<TEntity>(data);

        collection.CollectionChanged += (s, e) =>
        {
            if (e.NewItems != null)
            {
                context.AddRange(e.NewItems.Cast<TEntity>());
            }

            if (e.OldItems != null)
            {
                context.RemoveRange(e.OldItems.Cast<TEntity>());
            }
        };

        return collection;
    }
}

Note: it won't refresh the list if you query for more data. It will sync changes to the list back into the change tracker though.

来源：https://stackoverflow.com/questions/33819159/is-there-a-dbsettentity-local-equivalent-in-entity-framework-7