ASP.NET MVC4 with Entity Framework not passing fields in Edit operation

Question

I'm working on a small ASP.NET MVC4 web app with Entity Framework linking the app with my database. I let Visual Studio 2012 generate all the CRUD operations in the controller and views, and everything works OK except for Edit.

My generated object is as follows:

public partial class Post
{
    public Post()
    {
        this.Attachment = new HashSet<Attachment>();
    }

    [Display(AutoGenerateField = false)]
    public int post_id { get; set; } // This is the PK of my table
    public string title { get; set; }
    public string text { get; set; }
    [Display(AutoGenerateField = false)]
    public System.DateTime created { get; set; }
    [Display(AutoGenerateField = false)]
    public Nullable<System.DateTime> modified { get; set; }
    [Display(AutoGenerateField = false)]
    public string author { get; set; } // This is a FK from the "author" table

    public virtual ICollection<Attachment> Attachment { get; set; }
    public virtual Author Author1 { get; set; }
}

And the Edit POST operation is as follows:

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Edit(Post post)
{
    if (ModelState.IsValid)
    {
        post.modified = DateTime.Now;
        db.Entry(post).State = EntityState.Modified;
        db.SaveChanges(); // DbUpdateConcurrencyException thrown here
        return RedirectToAction("Index");
    }
    ViewBag.author = new SelectList(db.Author, "author1", "password", post.author);
    return View(post);
}

When I submit the edited post, ASP.NET spits out a DbUpdateConcurrencyException saying that the operation affected an unexpected number of rows (0).

When debugging, I found out that author, created and post_id are null; all of them should keep their values.

How can I fix this?

Thanks in advance.

Answer 1

On your Edit View() you should add these properties in hidden fields:

@Html.HiddenFor(m => m.post_id) etc.

That way they gonna bind on post model and you can use them in your edit method.