Get error message if ModelState IsValid fails

Question

I have this function in my controller    HttpPost  public ActionResult Edit EmployeesViewModel viewModel        Employee employee   GetEmployee viewModel EmployeeId       TryUpdateModel employee        if  ModelState IsValid                SaveEmployee employee           TempData  message      Employee has been saved            return RedirectToAction  Details   new   id   employee EmployeeID                return View viewModel      validation error  so redisplay same view     It keeps failing  ModelState IsValid keeps returning false and redisplaying the view  But I have no idea what the error is   Is there a way to get the error and redisplay it to the user

User · Answer

If anyone is here for WebApi  not MVC  you just return the ModelState object   return Request CreateErrorResponse HttpStatusCode BadRequest  ModelState

User · Answer

You can do this in your view without doing anything special in your action by using Html ValidationSummary   to show all error messages  or Html ValidationMessageFor   to show a message for a specific property of the model   If you still need to see the errors from within your action or controller  see the ModelState Errors property

User · Answer

I have no idea if this is your problem  but if you add a user and then change the name of your application  that user will remain in the database  of course   but will be invalid  which is correct behavior    However  there will be no error added for this type of failure   The error list is empty  but ModelState IsValid will return false for the login

User · Answer

Ok Check and Add to Watch    Do a breakpoint at your ModelState line in your Code Add your model state to your Watch  Expand ModelState  Values  Expand Values  Results View    Now you can see a list of all SubKey with its validation state at end of value   So search for the Invalid value

User · Answer

If Modal State is not Valid  amp  the error cannot be seen on screen because your control is in collapsed accordion  then you can return the HttpStatusCode so that the actual error message is shown if you do F12  Also you can log this error to ELMAH error log  Below is the code  if   ModelState IsValid                  var message   string Join        ModelState Values                                              SelectMany v   gt  v Errors                                               Select e   gt  e ErrorMessage                       Log This exception to ELMAH                  Exception exception   new Exception message ToString                     Elmah ErrorSignal FromCurrentContext   Raise exception                      Return Status Code                  return new HttpStatusCodeResult HttpStatusCode BadRequest  message       But please note that this code will log all validation errors  So this should be used only when such situation arises where you cannot see the errors on screen

User · Answer

Try  ModelState Values First   Errors 0  ErrorMessage

User · Answer

If you re looking to generate a single error message string that contains the ModelState error messages you can use SelectMany to flatten the errors into a single list   if   ModelState IsValid        var message   string Join        ModelState Values          SelectMany v   gt  v Errors           Select e   gt  e ErrorMessage        return new HttpStatusCodeResult HttpStatusCode BadRequest  message

User · Answer

publicIHttpActionResultPost Productproduct          if  ModelState IsValid                Dosomethingwiththeproduct notshown             returnOk            else             returnBadRequest                 OR public HttpResponseMessage Post Product product                        if  ModelState IsValid                                   Do something with the product  not shown                    return new HttpResponseMessage HttpStatusCode OK                             else                               return Request CreateErrorResponse HttpStatusCode BadRequest  ModelState

User · Answer

ModelState Values SelectMany v   gt  v Errors  ToList   ForEach x   gt   logger Error    x ErrorMessage  n

User · Answer

Try this  if  ModelState IsValid          go on as normal   else       var errors   ModelState Select x   gt  x Value Errors                              Where y  gt y Count gt 0                              ToList        errors will be a list of all the errors   If you want to display the errors to the user  all you have to do is return the model to the view and if you haven t removed the Razor  Html ValidationFor   expressions  it will show up   if  ModelState IsValid          go on as normal   else       return View model       The view will show any validation errors next to each field and or in the ValidationSummary if it s present

User · Answer

It is sample extension  public class GetModelErrors         Usage return Json to View         return Json new   state   false  message   new GetModelErrors ModelState  MessagesWithKeys           public class KeyMessages               public string Key   get  set            public string Message   get  set              private readonly ModelStateDictionary  entry      public GetModelErrors ModelStateDictionary entry                 entry   entry             public int Count                 return  entry ErrorCount            public string Exceptions string sp     n                 return string Join sp   entry Values              SelectMany v   gt  v Errors               Select e   gt  e Exception              public string Messages string sp     n                 string msg   string Empty          foreach  var item in  entry                        if  item Value ValidationState    ModelValidationState Invalid                                msg    string Join sp  string Join      item Value Errors Select i   gt  i ErrorMessage                                     return msg             public List lt KeyMessages gt  MessagesWithKeys string sp     lt p gt                     List lt KeyMessages gt  list   new List lt KeyMessages gt             foreach  var item in  entry                        if  item Value ValidationState    ModelValidationState Invalid                                list Add new KeyMessages                                       Key   item Key                      Message   string Join null  item Value Errors Select i   gt  sp   i ErrorMessage                                                       return list

[c#] Get error message if ModelState.IsValid fails?

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