Question

I am new to MVC3 and am trying to write a blog application as a learning tool.

I’ve created a database object for the blog post and generated a controller using the Controller with Read/Write actions and views using Entity Framework to control the entity.

I’m having troubles with the edit commands. There are about 6 properties for a blog post but I only want to allow the edit to modify the title and content of the post. My code is as follows:

public ActionResult Edit(int id)
    {
        blog_Post blog_post = db.blog_Post.Find(id);
        return View(blog_post);
    }

    //
    // POST: /Post/Edit/5

    [HttpPost]
    public ActionResult Edit(blog_Post blog_post)
    {
        if (ModelState.IsValid)
        {
            db.Entry(blog_post).State = EntityState.Modified;
            db.SaveChanges();
            return RedirectToAction("Index");
        }
        return View(blog_post);
    }

@model BlogVersion1._0.blog_Post

@{
    ViewBag.Title = "Edit";
}

<h2>Edit</h2>

@using (Html.BeginForm()) {
@Html.ValidationSummary(true)
<fieldset>
    <legend>blog_Post</legend>

    <div class="editor-label">
        @Html.LabelFor(model => model.Title)
    </div>
    <div class="editor-field">
        @Html.EditorFor(model => model.Title)
        @Html.ValidationMessageFor(model => model.Title)
    </div>

    <div class="editor-label">
        @Html.LabelFor(model => model.PostContent)
    </div>
    <div class="editor-field">
        @Html.EditorFor(model => model.PostContent)
        @Html.ValidationMessageFor(model => model.PostContent)
    </div>

    <p>
        <input type="submit" value="Save" />
    </p>
</fieldset>
}

<div>
@Html.ActionLink("Back to List", "Index")
</div>

The problem that comes about is in the public ActionResult Edit(blog_Post blog_post) method. In the Edit(int id) method, I have put a breakpoint in and I can see that blog_post is being properly passed to the view (including all of its properties populated).

But the blog_post being returned to the [HttpPost] method is missing properties for UserId, DateCreated, etc. An exception is obviously thrown on the db.SaveChanges call as required foreign keys are missing.

How do I ensure that all properties are returned to the second edit method to properly make the update?

Answer 1

Just add hidden fields for all other, non-editable properties.

@Html.HiddenFor(model => model.Id)

These field will be included in POST and hence, model binder will correctly put them into your blog_post instance.

On the other side, you should really be using view models – simple POCO classes that will be models for your views. Using entity models directly is not recommended.

Here’s some info on that:
ASP.NET MVC ViewModel Pattern
http://stephenwalther.com/archive/2009/04/13/asp-net-mvc-tip-50-ndash-create-view-models.aspx