How to return message from MVC controller to AngularJS controller

Issue

I need to add a warning message to the user, so if they try to insert records that have meeting id == 0 a message is returned making them aware.

My current AngularJS code to save the data, invoking the ImportData method in C#

// Save data to sql database  
$scope.SaveData = function (excelData) {
    $http({
        method: "POST",
        url: "/Home/ImportData",
        data: JSON.stringify(excelData),
        headers: {
            'Content-Type': 'application/json'
        }
    }).then(function (data) {
        if (data.status) {
            $scope.Message = excelData.length + " Record Successfully Inserted";
            $scope.GetData();
        }
        else {
            $scope.Message = "Failed";
        }
    }, function (error) {
        $scope.Message = "Error";
    });
};

C# code:

 [HttpPost]
 public ActionResult ImportData (List<Meeting_WIP> meeting) {
     bool status = false;
     try {
         if (ModelState.IsValid) {
             using (MeetingEntities db = new MeetingEntities ()) {
                 foreach (var i in meeting) {
                     if (i.MeetingID == 0) {
                         throw new ArgumentException ("Meeting ID cannot be null or empty string", i.MeetingID.ToString ());
                     } else {
                         var compositeKey = db.Meeting_WIP.Find (i.MeetingID, i.AgendaItem);

                         if (compositeKey == null) {
                             // Meeting ID does not exist in database it is a new one 
                             db.Meeting_WIP.Add (i);
                         } else {
                             // Meeting ID already exist in database just update record
                             db.Entry (compositeKey).CurrentValues.SetValues (i.MeetingID);
                             db.Entry (compositeKey).State = EntityState.Modified;
                         }
                     }
                 }

                 db.SaveChanges ();
                 status = true;
             }
         }
     } catch (Exception ex) {
         ExceptionLogging.SendErrorToText (ex);
     }
     return new JsonResult { Data = new { status = status } };
 }

Currently even if the excel data file contains a Meeting ID == 0, the message that is displayed is:

$scope.Message = excelData.length + " Record Successfully Inserted";

How can I tell tthe Angular code when Meeting ID == 0, then return an error and display something like:

"Meeting ID cannot be zero/null"

screen shot of angularjs code debug

Solution

Since you are throwing argument exception when meeting ID is zero, you should catch that exception and set status and validation message accordingly.

[HttpPost]
  public ActionResult ImportData (List<Meeting_WIP> meeting) {
      bool status = false;
      string message = "";

      try {
          if (ModelState.IsValid)

          {

              using (MeetingEntities db = new MeetingEntities ())

              {

                  foreach (var i in meeting)

                  {

                      if (i.MeetingID == 0)

                      {
                          throw new ArgumentException ("Meeting ID cannot be null or empty string", i.MeetingID.ToString ());
                      } else

                      {

                          var compositeKey = db.Meeting_WIP.Find (i.MeetingID, i.AgendaItem);

                          if (compositeKey == null)

                          {
                              // Meeting ID does not exist in database it is a new one 
                              db.Meeting_WIP.Add (i);
                          } else

                          {
                              // Meeting ID already exist in database just update record
                              db.Entry (compositeKey).CurrentValues.SetValues (i.MeetingID);
                              db.Entry (compositeKey).State = EntityState.Modified;
                          }

                      }

                  }

                  db.SaveChanges ();
                  status = true;
              }
          }
      } catch (Exception ex) {
          ExceptionLogging.SendErrorToText (ex);
      } catch (System.ArgumentException ae) {
          status = false;
          message = "Meeting ID cannot be zero/null";
      }
      return new JsonResult { Data = new { status = status, message = message } };
  }

you can add a new property to your json result for validation message and set value as "Meeting ID cannot be zero/null"

if (data.data.status == true) {
    $scope.Message = excelData.length + " Record Successfully Inserted";
    $scope.GetData();
}
else {
    $scope.Message = data.data.message;
}

Answered By - NTP