title: Why does validation break on partial view?
body: <p>This validation should work, but the post fires right past it if there are no selected values in the dropdown. When moved to another non-partial the validation works just fine. Edited for brevity.</p>
  
  <p>ViewModel:</p>
  
  <pre><code>public class BuilderVM
  {
      [Display(Name = "Select A Task")]
      [Required]
      public int? TaskId { get; set; }
      public GenericSelectList Tasks { get; set; }
  }
  </code></pre>
  
  <p>Parent View (the partial view is rendered at the bottom of this page after a post. as you may have noticed, the ajax options dictate that the partial view will be rendered in div <code>id="MoveOn"</code>):</p>
  
  <pre><code>@{
   ViewBag.Title = "Builder";
   AjaxOptions ajaxOpts = new AjaxOptions
   {
      LoadingElementDuration = 2,
      LoadingElementId = "removeChoice",
      UpdateTargetId = "MoveOn"
   };
  }
  &lt;div id="removeChoice"&gt;
  @using (Ajax.BeginForm("Selected", ajaxOpts))
  {
  &lt;fieldset&gt;
      &lt;div&gt;
       //Data For Submission (This data validates perfectly before post)
      &lt;/div&gt;
      &lt;p&gt;&lt;input type="submit" value="Go" /&gt;&lt;/p&gt;
  &lt;/fieldset&gt;
  }
  &lt;/div&gt;
  &lt;div id="MoveOn"&gt;&lt;/div&gt;
  </code></pre>
  
  <p>Partial View (rendered after a post from parent view):</p>
  
  <pre><code>@model namespace.BuilderVM
  @{
   AjaxOptions ajaxOpts = new AjaxOptions
    {
      UpdateTargetId = "Entry",
      LoadingElementDuration = 2,
      LoadingElementId = "RemoveEntry"
    };
  }
  
  &lt;div id="RemoveEntry"&gt;
  &lt;h2&gt;Details&lt;/h2&gt;
  @using (Ajax.BeginForm("Data", ajaxOpts))
  {
  @Html.ValidationSummary(true)
  &lt;fieldset&gt;
  &lt;legend&gt;Data&lt;/legend&gt;
  &lt;div&gt;
      &lt;span class="label"&gt;@Html.LabelFor(model =&gt; model.TaskId)&lt;/span&gt;
      &lt;span class="content"&gt;
      @Html.DropDownListFor(
          model =&gt; model.TaskId,
          new SelectList(
              Model.Tasks.Values,
              "Id",
              "DisplayFields",
              Model.Tasks.StartValue
          ),
          Model.Tasks.Message
      )
      &lt;/span&gt;@Html.ValidationMessageFor(model =&gt; model.TaskId)
  &lt;/div&gt;
  &lt;p&gt;&lt;input type="submit" value="Add Work Completed Data" /&gt;&lt;/p&gt;
  &lt;/fieldset&gt;
  }
  &lt;/div&gt;
  &lt;div id="Entry"&gt;&lt;/div&gt;
  </code></pre>
  
  <p>Although the dropdownlistfor is bound to model.TaskId which is annotated with <code>[Required]</code> when the post button is clicked (<code>input type="submit"</code>) and there is no value selected in the dropdownlist the post goes through instead of stopping and appending the validation message. I am not sure what to do to fix this, as it works just fine when copy pasted to a regular view. Why wont the partial view validation work?</p>