Value cannot be null. Parameter name: items (DrodownList)

by

Consider the case when model validation fails. View will be redisplayed again with model sent with the request. However this line:

new SelectList(ViewBag.Districts, "district_id", "district_name", Model.Districts)

will have null as a first parameter, since ViewBag.Districts was not repopulated, causing the exception. So in order to avoid exception just set this property again:

// If we got this far, something failed, redisplay form
var districts = repository.GetDistricts();
ViewBag.Districts = districts;
return View(model);

Update. When seeing the model definition, thing that immediately comes into the mind is Required attribute of the Districts collection. Most likely you do not need user to enter any of those, nor you save them into the database. Try removing this attribute, and error about this property will disappear.

More Related Contents:

  1. Can an ASP.NET MVC controller return an Image?
  2. In asp.net mvc is it possible to make a generic controller?
  3. What is ASP.NET Identity’s IUserSecurityStampStore interface?
  4. Best way to trim strings after data entry. Should I create a custom model binder?
  5. Has anyone implement RadioButtonListFor for ASP.NET MVC?
  6. Return XML from a controller’s action in as an ActionResult?
  7. How to programmatically clear outputcache for controller action method
  8. What is the equivalent of Server.MapPath in ASP.NET Core?
  9. How to receive JSON as an MVC 5 action method parameter
  10. ASP.NET 4.5 MVC 4 not working on Windows Server 2008 IIS 7
  11. ASP.Net MVC Handling Segments with Route
  12. WebAPI to Return XML
  13. mvc uppercase Model vs lowercase model
  14. I’m lost. What happened to ASP.NET MVC 5?
  15. You must add a reference to assembly ‘netstandard, Version=2.0.0.0
  16. Infinite URL Parameters for ASP.NET MVC Route
  17. How to remove returnurl from url?
  18. What is the difference between and ?
  19. The anti-forgery cookie token and form field token do not match in MVC 4
  20. Linq Orderby random ThreadSafe for use in ASP.NET
  21. ASP.NET MVC Relative Paths
  22. Difference Between ViewResult() and ActionResult()
  23. Unable to create an object of type ‘[DBContext’s Name]’. For the different patterns supported at design time [closed]
  24. ‘System.Net.Http.HttpContent’ does not contain a definition for ‘ReadAsAsync’ and no extension method
  25. Streaming large file uploads to ASP.NET MVC
  26. Diagnosing 404 errors on IIS 7 and ASP.NET MVC
  27. Custom app_offline.htm file during publish
  28. ASP.NET session state and multiple worker processes
  29. IValidatableObject Validate method firing when DataAnnotations fails
  30. ASP.Net MVC RedirectToAction with anchor

Leave a Comment