Object Reference Null - Passing jQuery Array To C# List

Question

I've a simple issue but it got complicated. I am trying to pass an array of object using jQuery and in the back-end, I am using C# to get the list. So this is what I've tried so far:

jQuery:

$('#btnStrickOff').on('click', function () {
    var formData = new FormData();
    debugger;
    var rowindexes = $('#jqxgrid').jqxGrid('getselectedrowindexes');

    for (var i = 0; i < rowindexes.length; i++) {

        var row = $('#jqxgrid').jqxGrid('getrowdata', rowindexes[i]);

        formData.append('strData[' + i + '].empno', row.empno);
        formData.append('strData[' + i + '].Name', row.Name);
        formData.append('strData[' + i + '].Des', row.Des);
        formData.append('strData[' + i + '].Dept', row.Dept);
        formData.append('strData[' + i + '].Section', row.Section);

        formData.append('strData[' + i + '].Emp_type', row.Emp_type);
        formData.append('strData[' + i + '].LateAtt', row.LateAtt);
        formData.append('strData[' + i + '].Diff', row.Diff);
    }

    var url = '@Url.Action("InsertStrikeOff")';

    debugger;

    $.ajax({
        type: 'POST',
        url: url,
        dataType: 'json',
        data: JSON.stringify({ 'things': formData }),
        contentType: false,
        processData: false,
        async: false,
        success: function (data) {
            alert("Updated. - "+data);
        }
    });
});

So the idea is: There is a table and each row has a CheckBox associated with it. Whenever user checks a row or multiple, it should have the row data in an Array and iterate through, then passes to the C# controller in the Ajax call. Here is the C# code section:

C#:

public JsonResult InsertStrikeOff(List<DailyStrikeOffBO> things)
{
   DateTime strikeDate = DateTime.Now;
   var value = (dynamic)null;
   foreach (var item in things)
   {
      bool chk = Facede.StrikeOff.CheckStrikeOff(item.empno);

      if (chk == false)
      {
         bool aStrikeOffBo = Facede.StrikeOff.InserstrikeOffLst2(item.empno, item.Name, item.LateAtt, strikeDate, item.remarks);
         value = "<div style='color:green;'>Striked-off request sent!</div>";
      }
      else
      {
         value = "<div style='color:red;'>Already striked off!</div>";
      }
   }

  return Json(value, JsonRequestBehavior.AllowGet);
}

Unfortunately, I am getting this error every time when it calls the C# controller though I am quite sure I am doing the right thing - Object reference not set to an instance of an object. Anything that I missed here?

Update 1: Model

public class DailyStrikeOffBO
{
    public string empno { get; set; }
    public string Name { get; set; }
    public string Des { get; set; }
    public string Dept { get; set; }
    public string Section { get; set; }
    public string Emp_type { get; set; }
    public string Diff { get; set; }
    public string LateAtt { get; set; }
}

Update 2:

Note: I can see the data iterated in the JavaScript loop using browser console. — AT-2017
– AT-2017, Commented Sep 8, 2018 at 9:11
I'd simply skip the FormData and stitch together the string of array of objects. — Filburt
– Filburt, Commented Sep 8, 2018 at 9:25

user3559349 · Accepted Answer · 2018-09-08 09:10:53Z

1

You cannot post an object containing FormData - you need to send the actual FormData object. In addition your name do not match the model you are posting to, which is a collection, not an object containing a collection.

Assuming DailyStrikeOffBO contains properties empno, Name,Des` etc, then you need to append the name/value pairs as

formData.append('[' + i + '].empno', row.empno);
formData.append('[' + i + '].Name', row.Name);
formData.append('[' + i + '].Des', row.Des);
.... // etc

and then modify the ajax option to

$.ajax({
    type: 'POST',
    url: url,
    dataType: 'json',
    data: formData , // modify
    contentType: false,
    processData: false,
    async: false,
    success: function (data) {
        alert("Updated. - "+data);
    }
});

answered Sep 8, 2018 at 9:10

user3559349

Sign up to request clarification or add additional context in comments.

6 Comments

AT-2017 Over a year ago

I've already tried that too @Stephen Muecke. But still the same - Will try it again and let you know.

user3559349 Over a year ago

If its not working, then you need to show us your DailyStrikeOffBO model

user3559349 Over a year ago

The model is fine. The code in my answer will work fine. What problems are you still having?

AT-2017 Over a year ago

I am still getting the error @Stephen Muecke. See the sample image.

user3559349 Over a year ago

Not possible if you made the changes I noted. But that image shows a model which is StrikeOffNew, not DailyStrikeOffBO that the data is based on.

|

AnkitG · Accepted Answer · 2018-09-08 11:20:10Z

for (a = 0; a < rowindexes.length; a++) {
            var row = $('#jqxgrid').jqxGrid('getrowdata', rowindexes[i]);
                var model = {
                    empno : row.empno,
                    Name: row.Name,                    
                    Des: row.Des,
                    Dept: row.Dept,
                    Section: row.Section,
                    Emp_type:  row.Emp_type,
                    Diff: row.Diff,
                    LateAtt: row.LateAtt
                };

                data.push(model);
            }   
var modelString = JSON.stringify(data);
    $.ajax({
        type: 'POST',
        url: url,
        dataType: 'json',
        data: modelString ,
        contentType: "application/json; charset=utf-8",
        processData: false,       
        success: function (data) {
            alert("Updated. - "+data);
        }
    });

Instead of using FormData try using json object. The way you are passing data thru ajax ( data: JSON.stringify({ 'things': formData }), ) that is also not correct.

Try the above code, let me know how it goes.

Collectives™ on Stack Overflow

Object Reference Null - Passing jQuery Array To C# List

2 Answers 2

6 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

6 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related