title: Html.BeginForm posted Model is null
body: <p>Hello I have following problem:
  I tried to post a Model through a Form to an other controller-action.
  But the received Model is only filled with <code>null</code> elements.
  <a href="https://i.stack.imgur.com/mPCcG.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/mPCcG.png" alt="enter image description here"></a></p>
  
  <p><strong>ToolController.cs</strong></p>
  
  <pre><code>public class ToolController : Controller
  {    
      public ActionResult Index()
      {
          var Model = new EditToolModel{ /* Some data */ };
          return View(Model);
      }
  
      [HttpPost]
      public ActionResult EditToolOverview(EditToolModel myModel)
      {
          return RedirectToAction("Index", "Tool", new { show = "overview" });
      }
  }
  </code></pre>
  
  <p><strong>EditToolModel.cs</strong></p>
  
  <pre><code>public class EditToolModel
  {
      public Tools tool;
      public IEnumerable&lt;Tools&gt; tools { get; set; }
  
      public ToolsExtention tool_extention;
      public string latest_version { get; set; }
      public string latest_version_type { get; set; }
      public string latest_devStep { get; set; }
  
      public IEnumerable&lt;ToolVersionsView&gt; versions { get; set; }
      public IEnumerable&lt;DevelopmentStep&gt; developmentSteps { get; set; }
  }
  </code></pre>
  
  <p><strong>Index.cshtml</strong></p>
  
  <pre><code>@model EditToolModel
  @{
      ViewBag.Title = "Index";
      Layout = "~/Layout/_Layout.cshtml";
  }
  @Html.Partial("ToolOverview", this.Model)
  </code></pre>
  
  <p><strong>ToolOverview.cshtml</strong></p>
  
  <pre><code>@model EditToolModel
  @using (Html.BeginForm("EditToolOverview", "Tool", FormMethod.Post))
  {
      &lt;div class="contend"&gt;
          @Html.TextBoxFor(Model =&gt; Model.tool_extention.a)
          @Html.TextBoxFor(Model =&gt; Model.tool_extention.b)
          &lt;input type="submit" name="tool_submit" value="Submit"/&gt;
      &lt;/div&gt;
  }
  </code></pre>