title: Sending model data from Knockout back to MVC 3
body: <p>I am new to knockout and am having a hard time trying to get my data from Knockout back to my server.  I keep getting an error of 'No parameterless constructor defined for this object.'  Any help would be appreciated.</p>
  
  <p>My Knockout model is as follows</p>
  
  <pre><code>        function partSummary(item) {
              var self = this;
              self.ID = ko.observable(item.ID);
              self.serialNumber = ko.observable(item.SerialNumber);
              self.description = ko.observable(item.Description);
              self.manufacturer = ko.observable(item.Manufacturer);
              self.creationDate = ko.observable(item.DateCreated);
              self.active = ko.observable(item.IsActive);
          }
  </code></pre>
  
  <p>My code to send the data back the server is </p>
  
  <pre><code>self.savePart = function() {
                  $.ajax("/PartKO/UpdatePart", {
                      data: ko.toJSON(self.partDetails),
                      type: "post",
                      contentType: 'application/json',
                      dataType: 'json'
                  });
              };
  </code></pre>
  
  <p>My MVC controller is </p>
  
  <pre><code>[HttpPost]
      public JsonResult UpdatePart(PartDetail part)
      {
          var dbPart = new PartGenericAccessor();
          dbPart.ID = part.ID;
          dbPart.Load();
          dbPart.Description = part.Description;
          dbPart.IsActive = Convert.ToBoolean(part.IsActive);
  
          var manufacturers = ManufacturerAccessor.LoadAll&lt;ManufacturerAccessor&gt;();
          if (part.Manufacturer != null)
          {
              var manufacturer = (from p in manufacturers where p.Name == part.Manufacturer select p.ID).First();
              dbPart.ManufacturerID = manufacturer;
          }
  
          dbPart.Save();
  
          return Json("Success!!");
      }
  </code></pre>
  
  <p>And my server side model is </p>
  
  <pre><code>    public class PartDetail
  {
      public PartDetail(Guid id, string serial, string description, string manufacturer, DateTime created, bool isActive)
      {
          ID = id;
          SerialNumber = serial;
          Description = description;
          Manufacturer = manufacturer;
          DateCreated = created.ToShortDateString();
          IsActive = isActive.ToString(CultureInfo.InvariantCulture);
  
      }
  
      public Guid ID { get; set; }
  
      public string SerialNumber { get; set; }
  
      public string Description { get; set; }
  
      public string Manufacturer { get; set; }
  
      public string DateCreated { get; set; }
  
      public string IsActive { get; set; }
  }
  </code></pre>