Entity Framework - Eager loading related entities

Question

I\'m using Entity Framework 4 with MVC and need to ensure any referenced entities I want to use in my view have been loaded before the controller method returns, otherwise the v

Answer 1

I think this is a job for your repository which should in your case expose methods like GetFullSeller (all properties loaded by Include) and GetSeller (only base entity).

Edit:

There are several ways how to load navigation properties in EF v4.

• Eager loading (using Include)
• Lazy loading
• Explicit loading by ObjectContext.LoadProperty (doesn't work for POCO)

There is no automatic loading.

Answer 2

Rather than passing your actual domain objects (EntityObjects) to the view, you may want to use your controller to map them into a Model object that better represents what your view should actually be displaying. This will reduce the amount of logic required in your View, and have the pleasant side-effect of avoiding passing EntityObjects around after their context has expired.

Edit based on your edit:

No, the API doesn't have a way to take a single Entity Object and make every other Entity Object of its type which was loaded at the same time it was be lazy-populated with a particular property in one fell swoop. You are better off pulling all of the items out in the first place using the Include mention like you show in your question.

Answer 3

This is an old question, but in EF6 you can accomplish loading dependent objects on an entity like this:

context.Entry(seller).Collection(s => s.Recommendations).Query().Include(r => r.User)).Load();

That would load all Recommendations and their related Users for the given seller

Answer 4

I'm in the same situation. I think that with EF is very easy to fall in a 101 query problem.

A solution can be to create a partial class of your Seller class (generated by EF) and implement a GetSubclassNameQ that return a IQueryable, and a GetSubclassNameQFull that return a IQueryable with eager loading.

public partial class Seller{

  public IQueryable<Recommendation> GetRecommendationsQ(EntityContainer entitycontainer) {
    return entitycontainer.Recommendations;
  }      

  public IQueryable<Recommendation> GetRecommendationsQFull(EntityContainer entitycontainer) {
    return this.GetRecommendationsQ(entitycontainer).Include("Recommendations.User");
  }

  public IQueryable<Recommendation> GetRecommendationsQ() {
    return GetRecommendationsQ(new EntityContainer());
  }

  public IQueryable<Recommendation> GetRecommendationsQFull() {
    return this.GetRecommendationsQ().Include("Recommendations.User");
  }

}