ASP.NET MVC Entity Framework Relationship binding

Question

I'm using Entity Framework 5.0 for my MVC4 project. There's a problem with it. When i give a db model to any view, controller send model with no relationship

example;

I have User class and with relation departments

when i use it in controller

using(context)
{
  var user = context.Find(id);
  string department = user.Department.Name;
}

its working when call in context. but when i do that

using(context)
{
  var user = context.Find(id);
  return View(user);
}

and call in view like

Model.Department.Name

i got error.

Here is my answer but its not good

using(context)
{
  var user = context.Find(id);
  string department = user.Department.Name;
  return View(user);
}

when i try to user Model.Department.Name in view i got no error i must do that for every relation when i use class as model. there is have better solution for this problem ? i want use all relationship in View without call these in controller.

I hope you can understand me, sorry my english.

"The ObjectContext instance has been disposed and can no longer be used for operations that require a connection." Its the error i can fix it with call relations at controller but i dont want call them all all the time there should have a binding function or something with ef — alim
– alim, Commented Feb 25, 2013 at 12:54
Have you tried instead of Model.Department.Name to have Model.User in the view? — idipous
– idipous, Commented Feb 25, 2013 at 12:59

Darin Dimitrov · Accepted Answer · 2013-02-25 13:06:10Z

1

On your DbContext you could use the .Include method to eagerly load the relations you need:

context.Users.Include(u => u.Department).FirstOrDefault(u => u.Id == id);

or if you are using an older version of entity Framework the generic version of this method might not be available:

context.Users.Include("Department").FirstOrDefault(u => u.Id == id);

answered Feb 25, 2013 at 13:06

Darin Dimitrov

1.0m276 gold badges3.3k silver badges3k bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

alim Over a year ago

Ok i got it Darin, here is another question about this. I have older version 5.0 ef. there another realtionship too like var alluserInYourDepartment = User.Department.Users; what about that Include method include it ? :)

Steve Gordon · Accepted Answer · 2013-02-25 13:12:15Z

1

The reason for this is that you haven't "loaded" the Department in your original code. As your context is wrapped in a using statement it's being disposed of before the view is created and therefore your user object lacks the data you want.

In your second code example you have specifically called into the related Department object and therefore it now exists within the User object.

You need to eager load the Department in your original line using something like

context.User.Include(c => c.Department).Find(id);

Now your user object should have this available in the view.

answered Feb 25, 2013 at 13:12

Steve Gordon

172 bronze badges

4 Comments

alim Over a year ago

here is another question about this. I have older version 5.0 ef. there another realtionship too like var alluserInYourDepartment = User.Department.Users; what about that Include method include it ? :)

Steve Gordon Over a year ago

Without seeing more of the code it's hard to help. I think you need to read up on how EF works. Assuming your models have the proper navigation properties (so your Department has a public ICollection<User> Users { get; set; } property) then you should be able to use User.Department.Users as you suggest to get all users from the department for a given user. I've tried a very simple test here and it worked without further includes.

alim Over a year ago

mvc3-4 ? ef 4.0 or 5.0 or 6.0 which one is your using ?

Steve Gordon Over a year ago

I'm using MVC4 and EF 5.0 but I believe this concept should apply to all versions.

JeppePepp · Accepted Answer · 2013-02-25 13:25:39Z

1

What are u trying to accomplish? List a view for a user with one or many departments?

answered Feb 25, 2013 at 13:25

JeppePepp

5891 gold badge12 silver badges22 bronze badges

1 Comment

alim Over a year ago

no, think like that i have vehicles, vehiclerequests, vehiclerequestapproves. When i want see vehicle request detail at view i should see which user did what like user a approved user b cancel user c didnt response. so i must do that for each request.Approves approve.User.Username like that so its mean one include didnt enougth

Collectives™ on Stack Overflow

ASP.NET MVC Entity Framework Relationship binding

3 Answers 3

1 Comment

4 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

4 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related