title: Do I have to reassign a partial view's data back to the model when POSTing back to my controller?
body: <p>Newbie ASP.NET MVC question:</p>
  
  <p>I have the following model:</p>
  
  <pre><code>public class Customer
  {
      public string FirstName { get; set; }
      public string LastName { get; set; }
      public Address Address { get; set; }
  }
  </code></pre>
  
  <p>And the following view for customer:</p>
  
  <pre><code>&lt;% using (Html.BeginForm()) { %&gt;
      First Name: &lt;%=Html.TextBox("FirstName") %&gt;
      Last Name: &lt;%=Html.TextBox("LastName") %&gt;
      &lt;% Html.RenderPartial("AddressView", Model.Address); %&gt;
      &lt;input type="submit" name="btnSubmit" value="Submit"/&gt;
  &lt;%} %&gt;
  </code></pre>
  
  <p>And the following partial view for Address:</p>
  
  <pre><code>&lt;%=Html.DropDownList("CountryId", new SelectList(Country.GetAll(), "Id", "Name") })%&gt;
  &lt;%=Html.DropDownList("CountrySubdivisionId", new SelectList(CountrySubDivision.GetByCountryId(Model.CountryId), "Id", "Name"))%&gt;
  </code></pre>
  
  <p>And the following controller action:</p>
  
  <pre><code>    [AcceptVerbs(HttpVerbs.Post)]
      public ViewResult Index(Customer customer, Address address)
      {
          customer.Address = address;
          ViewData.Model = customer;
          return View();
      }
  </code></pre>
  
  <p>I was hoping that the action would work with 1 parameter: customer, and that I would not have to reassign customer.Address manually.  However, when the action is executed, Customer.Address is null.</p>
  
  <p>Am I using model binding incorrectly, or does my action require separate parameters for Customer and Address?</p>