Can you get the DbContext from a DbSet?

c#, dbcontext, dbset, entity-framework, entity-framework-4.1

Solution

Yes, you can get the `DbContext` from a `DbSet<TEntity>`, but the solution is reflection heavy. I have provided an example of how to do this below.

I tested the following code and it was able to successfully retrieve the `DbContext` instance from which the `DbSet` was generated. Please note that, although it does answer your question, there is almost certainly a better solution to your problem.

public static class HackyDbSetGetContextTrick
{ 
    public static DbContext GetContext<TEntity>(this DbSet<TEntity> dbSet)
        where TEntity: class
    { 
        object internalSet = dbSet
            .GetType()
            .GetField("_internalSet",BindingFlags.NonPublic|BindingFlags.Instance)
            .GetValue(dbSet);
        object internalContext = internalSet
            .GetType()
            .BaseType
            .GetField("_internalContext",BindingFlags.NonPublic|BindingFlags.Instance)
            .GetValue(internalSet); 
        return (DbContext)internalContext
            .GetType()
            .GetProperty("Owner",BindingFlags.Instance|BindingFlags.Public)
            .GetValue(internalContext,null); 
    } 
}

Example usage:

using(var originalContextReference = new MyContext())
{
   DbSet<MyObject> set = originalContextReference.Set<MyObject>();
   DbContext retrievedContextReference = set.GetContext();
   Debug.Assert(ReferenceEquals(retrievedContextReference,originalContextReference));
}

Explanation:

According to Reflector, `DbSet<TEntity>` has a private field `_internalSet` of type `InternalSet<TEntity>`. The type is internal to the EntityFramework dll. It inherits from `InternalQuery<TElement>` (where `TEntity : TElement`). `InternalQuery<TElement>` is also internal to the EntityFramework dll. It has a private field `_internalContext` of type `InternalContext`. `InternalContext` is also internal to EntityFramework. However, `InternalContext` exposes a public `DbContext` property called `Owner`. So, if you have a `DbSet<TEntity>`, you can get a reference to the `DbContext` owner, by accessing each of those properties reflectively and casting the final result to `DbContext`.

Update from @LoneyPixel

In EF7 there is a private field _context directly in the class the implements DbSet. It's not hard to expose this field publicly

Problem

In my application it is sometimes necessary to save 10,000 or more rows to the database in one operation. I've found that simply iterating and adding each item one at a time can take upwards of half an hour. However, if I disable AutoDetectChangesEnabled it takes ~ 5 seconds (which is exactly what I want) I'm trying to make an extension method called "AddRange" to DbSet which will disable AutoDetectChangesEnabled and then re-enable it upon completion. ``` public static void AddRange<TEntity>(this DbSet<TEntity> set, DbContext con, IEnumerable<TEntity> items) where TEntity : class { // Disable auto detect changes for speed var detectChanges = con.Configuration.AutoDetectChangesEnabled; try { con.Configuration.AutoDetectChangesEnabled = false; foreach (var item in items) { set.Add(item); } } finally { con.Configuration.AutoDetectChangesEnabled = detectChanges; } } ``` So, my question is: Is there a way to get the DbContext from a DbSet? I don't like making it a parameter - It feels like it should be unnecessary.

Original source