asp.net-mvc - MVC (EF 4.1) 中的 "Delete"post 方法中缺少某些内容

Question

按照这个例子.. http://msdn.microsoft.com/en-us/data/gg685489

我遇到了删除功能的问题。

[HttpPost]
public ActionResult Delete(int id, Blog blog)
{
    try
    {
        using (var db = new BlogDataEntities())
        {
            //Having issue here.. as soon as the next line is run in debug
            //mode .. it goes to catch.. and returns a view with null values.

            db.Entry(blog).State = System.Data.EntityState.Deleted;
            db.SaveChanges();
        }
        return RedirectToAction("Index");
    }
    catch
    {
        return View();
    }
}

在我检查“博客”的参数中，没有得到需要删除的实际博客模型。所有其他方法都可以正常工作(编辑、删除(获取)..等..但删除帖子失败。我错过了什么吗？提前感谢您的帮助。

编辑:

查看代码

@model DBFirstMVC.Models.Blog

@{
 ViewBag.Title = "Delete";
 }

  <h2>Delete</h2>

<h3>Are you sure you want to delete this?</h3>
<fieldset>
<legend>Blog</legend>

<div class="display-label">Title</div>
<div class="display-field">@Model.Title</div>

<div class="display-label">BloggerName</div>
<div class="display-field">@Model.BloggerName</div>
 </fieldset>
@using (Html.BeginForm()) {
  <p>
    <input type="submit" value="Delete" /> |
    @Html.ActionLink("Back to List", "Index")
  </p>
 }

编辑 2: View 中的非 Razor 代码:

<% using (Html.BeginForm()) { %>
<p>
    <input type="submit" value="Delete" /> |
    <%: Html.ActionLink("Back to List", "Index") %>
</p>
<% } %>

编辑 3:(我在 aspx 中试过)

<% using (Html.BeginForm()) { %>
<p>

    <%=Html.DisplayForModel();%> //Tried Html.EditorForModel also..
    <input type="submit" value="Delete" /> |
    <%: Html.ActionLink("Back to List", "Index") %>
</p>
<% } %>

最终编辑(更正的解决方案)

@model DBFirstMVC.Models.Blog

@{
 ViewBag.Title = "Delete";
}

<h2>Delete</h2>

<h3>Are you sure you want to delete this?</h3>

@using (Html.BeginForm()) {
 <p>
<fieldset>
<legend>Blog</legend>

<div class="display-label">Title</div>
<div class="display-field">@Model.Title</div>

<div class="display-label">BloggerName</div>
<div class="display-field">@Model.BloggerName</div>

  <input type="submit" value="Delete" /> |
@Html.ActionLink("Back to List", "Index")
</fieldset>
</p>
}

Answer 1

上下文可能没有您博客的条目，因为它没有附加到上下文。

您可能需要先检索博客，然后使用 Entry 方法将其标记为已删除:

[HttpPost]
public ActionResult Delete(int id, Blog blog)
{
    try
    {
        using (var db = new BlogDataEntities())
        {
            // retrieve the blog from the database
            var realBlog = db.Blogs.Find(blog.Id);

           // nothing to do here, just redirect
           if( realBlog == null )
                return RedirectToAction("Index");

          // since you have the entity just do this instead:
          db.Blogs.Remove(realBlog);
          db.SaveChanges();
        } 

        return RedirectToAction("Index");
    }
    catch( Exception )
    {
        return View();
    }
}

不过，我不太同意使用您的实体作为模型的想法。您应该改用 View 模型。

编辑

既然你现在说 Blog 没有被传递，试试这个:

@model Blog

@using ( Html.BeginForm() )
{
    @Html.EditorForModel()

    <input type="submit" value="Delete" />
}

您实际上并没有向模型绑定(bind)器提供构建模型所需的任何细节。