ASP.NET MVC 3, Entity Framework 4. Update entity with relation to many

Question

I want to update a "Post" and change relationships with "Categories" that already created before. Post entity has ICollection of Categories. But categories are not changed. It seems, that EF does not track entity relations. By the way I have no problem with creating of new Posts with assigning of Categories.

There are two models:

public class Post
{
    public virtual  int PostId { get; set; }
    ...
    public virtual ICollection<Category> Categories { get; set; }
}

public class Category
{
    public virtual int CategoryId { get; set; }
    ...
    public virtual ICollection<Post> Posts { get; set; }
}

The Add controller, that works as expected:

public ActionResult Create(Post model)
{
    var c = Request.Form["CategoryID"].Split(',');
    model.Categories = c.Select ... .ToList(); //here I assign relationships with attached objects
    _repository.Add(model);
    _repository.SaveChanges();
   ...         
}

Repository Add method:

T IRepository.Add<T>(T entity)
{
   return Set<T>().Add(entity);
}

The Edit controller does not save changed categories, only post props.

public ActionResult Edit(Post model)
{
   var c = Request.Form["CategoryID"].Split(',');
   model.Categories = c.Select ... .ToList(); //here I update relationships with attached objects
   _repository.Attach(model);
   _repository.SaveChanges();
   ...
}

Repository Edit method:

T IRepository.Attach<T>(T entity)
{
  var entry = Entry(entity);
  entry.State = System.Data.EntityState.Modified;
  return entity;
}

Am I doing something wrong?

Thanks in advance

Ievgen · Accepted Answer · 2012-03-31 10:12:43Z

2

Solution:

public ActionResult Edit(Post model)
    {
        model = _repository.Attach(model);
        var post = _repository.Posts.Include(p => p.Categories).Single(s => s.PostId == model.PostId);
        post.Categories.Clear();
        model.Categories = GetCategories();
        _repository.SaveChanges();
    }

First Attach the object (EntityState.Modified)
Query the object with Include or other method for Loading Related Entities
Clear the existent relations. I don like this, but I cannot find another way
Assign new relations from the view and SaveChanges.

answered Mar 31, 2012 at 10:12

Ievgen

8,0968 gold badges40 silver badges54 bronze badges

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

Comments

kubal5003 · Accepted Answer · 2011-09-03 23:00:40Z

1

Entity Framework won't track relationship changes this way. It only tracks the states of objects, so the proper way would be to load the "Post" that you want with all categories and then to modify the loaded collection - this way changes are going to be reflected in all objects' states.

answered Sep 3, 2011 at 23:00

kubal5003

7,2448 gold badges55 silver badges92 bronze badges

Comments

marvelTracker · Accepted Answer · 2011-09-04 05:21:42Z

0

Manipulate category collection i.e. (add, remove, edit) in post class. If you are using same DbContext then changes will be tracked. It should be worked.

add a category

_post.Categories.Add(category1);

delete category

_post.Categories.Remove(category1);

edit category

 _post.Categories[0].Name = "TEST Name";

answered Sep 4, 2011 at 5:21

marvelTracker

5,0074 gold badges39 silver badges50 bronze badges

Comments

user4584103 · Accepted Answer · 2016-05-17 11:29:43Z

0

udapte a object

 string ImgID = CompCert.CertID.ToString() + "ComID" + CompId + ext;
                        CompCert.CertImageFile = ImgID;
                        db.ObjectStateManager.ChangeObjectState(CompCert, EntityState.Modified);
                        db.SaveChanges();

answered May 17, 2016 at 11:29

user4584103

Collectives™ on Stack Overflow

ASP.NET MVC 3, Entity Framework 4. Update entity with relation to many

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related