How do you get the DataContext of a LINQ to SQL Entity?

Currently this is what I have:

public partial class LinqToSqlEntity {
   开发者_如何学C public IQueryable<AnotherLinqToSqlEntity> AnotherLinqToSqlEntities {
        using(DataContext context = new DataContext) {
            return context.AnotherLinqToSqlEntities.Where(item => item.Property == SOME_VALUE);
        }
    }
}

Is there a way to get the DataContext of this so that I would not need to create a new DataContext?

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Sorry, that is not possible. An entity or querable in that case keeps no direct reference of the context.

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You can achieve that using the reflection by figuring out if PropertyChanging event was hooked up, but consider this a hack and maybe you can avoid using it with better design. Our use case of this is on detach_EntityName delegate where we change the default Linq behaviour of only deleting the foreign key of a record (setting it to null), with the actual delete from DB.

public static DataContext GetDataContextFromEntityObject(object entity) 
{
    // Use a reflection to get the invocaiton list.
    var o = (PropertyChangingEventHandler)entity.GetType().GetField("PropertyChanging", BindingFlags.Instance | BindingFlags.NonPublic).GetValue(entity);
    var o = GetFieldValue(entity, "PropertyChanging");

    if (o == null) return null;
    var invocationList = o.GetInvocationList();
    if (invocationList != null)
    {
        // DataContext changes are tracked through StandardChangeTracker
        object changeTracker = (from i in invocationList where i.Target.GetType().FullName == "System.Data.Linq.ChangeTracker+StandardChangeTracker" select i.Target).FirstOrDefault();
        if (changeTracker != null)
        {
            object services = GetFieldValue(changeTracker, "services");
            return (DataContext)GetFieldValue(services, "context");
        }
    }

    return null;
}

private static object GetFieldValue(object instance, string propertyName)
{
    return instance.GetType().GetField(propertyName, BindingFlags.Instance | BindingFlags.NonPublic).GetValue(instance);
}