How to include a child object's child object in Entity Framework 5

Question

I am using Entity Framework 5 code first and ASP.NET MVC 3.

I am struggling to get a child object's child object to populate. Below are my classes..

Application class;

public class Application
{
     // Partial list of properties

     public virtual ICollection<Child> Children { get; set; }
}

Child class:

public class Child
{
     // Partial list of properties

     public int ChildRelationshipTypeId { get; set; }

     public virtual ChildRelationshipType ChildRelationshipType { get; set; }
}

ChildRelationshipType class:

public class ChildRelationshipType
{
     public int Id { get; set; }

     public string Name { get; set; }
}

Part of GetAll method in the repository to return all the applications:

return DatabaseContext.Applications
     .Include("Children");

The Child class contains a reference to the ChildRelationshipType class. To work with an application's children I would have something like this:

foreach (Child child in application.Children)
{
     string childName = child.ChildRelationshipType.Name;
}

I get an error here that the object context is already closed.

How do I specify that each child object must include the ChildRelationshipType object like what I did above?

Possible duplicate of [Entity Framework - Include Multiple Levels of Properties](https://stackoverflow.com/questions/10822656/entity-framework-include-multiple-levels-of-properties) — Michael Freidgeim, Sep 04 '18 at 14:16

Ryan Amies · Accepted Answer · 2016-10-21T22:17:38.577

290

If you include the library System.Data.Entity you can use an overload of the Include() method which takes a lambda expression instead of a string. You can then Select() over children with Linq expressions rather than string paths.

return DatabaseContext.Applications
     .Include(a => a.Children.Select(c => c.ChildRelationshipType));

edited Oct 21 '16 at 22:17

answered Oct 24 '12 at 11:39

Ryan Amies

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As GraemeMiller said, strongly typed classes are better for maintainability than using strings – Ryan Amies Oct 24 '12 at 14:08
Which version did the lamba method come available? I'm stuck on a EF 4.0 Codebase..and cant' get the lamdas to work. Thanks for any input. – granadaCoder Sep 02 '14 at 19:39
5

It will work in EF 4, just make sure to add a reference to `System.Data.Entity;` – Ryan Amies Sep 05 '14 at 11:08
5

FYI - In EF 6 the namespace is `Microsoft.Data.Entity` – Brad Aug 07 '15 at 22:45
1

Using EF 5, I could not get .Select(x => x.Child) but this worked - Entities.UserProfile storedProfile = db.UserProfiles .Include(s => s.ShippingAddress) .Include(st => st.ShippingAddress.StateProvince) .Include(b => b.BillingAddress) .Include(bs => bs.BillingAddress.StateProvince) .FirstOrDefault(x => x.UserId == userId); – Geovani Martinez Dec 28 '18 at 00:45
Thank you for mentioning the correct library to use, all too often people omit this important nugget of information. – Mike Jan 20 '21 at 01:29

Hayha · Answer 2 · 2019-05-15T23:07:24.130

165

With EF Core in .NET Core you can use the keyword ThenInclude :

return DatabaseContext.Applications
 .Include(a => a.Children).ThenInclude(c => c.ChildRelationshipType);

Include childs from childrens collection :

return DatabaseContext.Applications
 .Include(a => a.Childrens).ThenInclude(cs => cs.ChildRelationshipType1)
 .Include(a => a.Childrens).ThenInclude(cs => cs.ChildRelationshipType2);

edited May 15 '19 at 23:07

answered Mar 28 '17 at 16:56

Hayha

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Thanks!!! Really helpful! Sometimes you might get wrong intellisense, just ignore that and build! :) – muhihsan Aug 09 '17 at 06:48
1

Nice one, I was looking for .net core :) – Andy Clarke Sep 01 '17 at 12:32
2

And what if Children is a collection and I need to include properties under it? – dodbrian Jan 15 '18 at 12:36
Found an overload for that. Was not obvious at first. – dodbrian Jan 15 '18 at 12:52
Think you've got an extra parenthesis at the end there ;) – Gareth Sep 10 '18 at 18:14
3

@dodbrian What was the overload? I'm trying to nest .ThenInclude, where the child is a collection. – Greg Hardin Sep 21 '18 at 19:14
Glad I didn't stop at the first "answer" :) – LawMan May 18 '20 at 20:25

score 25 · Answer 3 · edited May 20 '18 at 11:45

25

I ended up doing the following and it works:

return DatabaseContext.Applications
     .Include("Children.ChildRelationshipType");

edited May 20 '18 at 11:45

mattruma

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answered Oct 24 '12 at 12:42

Brendan Vogt

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The strongly typed way is better. Magic strings aren't good for refactoring – GraemeMiller Oct 24 '12 at 13:20
@GraemeMiller , you re right, it is a lot better when debugging, refactoring or changing the code in any way, but (sadly) "strongly typed" just does not work - for me. So I'm stuck with magic stings. – Tamas Feb 07 '23 at 13:54
I will go with a solution using `nameof` expressions: `string.join('.', nameof(Children), nameof(Children.ChildRelationshipType))` - at least I will be able to "FindAllReferences" – Tamas Feb 07 '23 at 14:14

score 3 · Answer 4 · answered Apr 08 '16 at 17:52

3

A good example of using the Generic Repository pattern and implementing a generic solution for this might look something like this.

public IList<TEntity> Get<TParamater>(IList<Expression<Func<TEntity, TParamater>>> includeProperties)

{

    foreach (var include in includeProperties)
     {

        query = query.Include(include);
     }

        return query.ToList();
}

answered Apr 08 '16 at 17:52

gcoleman0828

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How would I call the above method? could you provide an example – Jamee Oct 01 '16 at 07:07
@Jamee -List>> includers = new List>>(); includers.Add(x => x.FirstName); Get(includers); – gcoleman0828 Dec 22 '16 at 18:53
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And query comes from...? – Doug Beard Mar 02 '17 at 17:33
Sorry @DougBeard, not following your question. – gcoleman0828 Jul 30 '17 at 13:21
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@gcoleman0828 The query variable in your code snippet above. Is it magically instantiated? Where does it come from? – Doug Beard Jan 23 '18 at 16:28
1

@DougBeard: the query can be extracted via dbContext.Person.Where clause, a query builder, or from an IEnumerable in which you apply AsQueryable() – Dan Mihalea Oct 22 '19 at 07:59

How to include a child object's child object in Entity Framework 5

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