Entity Data Model Associations and MVC 1 .NET giving NULL on Associated objects but allowing Linq to Entities Filtering

Question

I have a EDM that was wizard generated from an SQL 2005 Express database. For example, I have a table named Projects with a relationship to a table named People. Projects have two relationships on the People table primary key as foreign key in the People table (ChamipionID and LeaderID).

I have cleaned up all of the names for the Entities, Entity Sets and Associations and verified that the Association mappings are what I expect them to be.

When I write a Linq to Entities query against this, the association "Leader" which is mapping LeaderID to PeopleID of data type int64 (long) is always returned as null in the View Model in an MVC 1 website.

for example

var object = (from p in _entities.Projects 
              where p.Leader.PeopleID == 1 
              select p);

always yeilds null for object.Leader even though the association allowed for the filtering to happen correctly and the project data is all there.

even if I write the query like this..

var object = (from p in _entities.Projects 
              from pe in _entities.PeopleSet 
              where pe.PeopleID == 1 
              select p);

the result is the same

does anyone know why this happens? What am I missing?

Answer 1

EF 1 will never load a related type unless you force it.

I'd strongly recommend decoupling your views from entity types. Then you can force loading the correct properties (and only the correct properties) via projection:

var object = (from p in _entities.Projects 
              where p.Leader.PeopleID == 1 
              select new ViewModel
              {
                  ProjectName = p.Name,
                  LeaderName = p.Leader.Name
              });

Now the Leader info will be loaded and your view is persistence-ignorant.

Answer 2

Hello,

You can also do it when accessing the object:

if (!entity.Project.IsLoaded) entity.Project.Load();

As another alternative, which obviously isn't at the query level.