Json.NET sample code keeps giving me a 'System.NullReferenceException'

Asked May 23 '15 at 13:21

Active May 23 '15 at 13:29

Viewed 24 times

I just copied the code from their official documentation and just changed "Console.WriteLine" to "lblDebug.Text".

string json = @"{
  'Table1': [
    {
      'id': 0,
      'item': 'item 0'
    },
    {
      'id': 1,
      'item': 'item 1'
    }
  ]
}";

DataSet dataSet = JsonConvert.DeserializeObject<DataSet>(json);

DataTable dataTable = dataSet.Tables["Table1"];

lblDebug.Text += dataTable.Rows.Count +"";
// 2

foreach (DataRow row in dataTable.Rows)
{
    lblDebug.Text += row["id"] + " - " + row["item"];
}

Soruce of the original sample: http://www.newtonsoft.com/json/help/html/DeserializeDataSet.htm

Everytime I compile it throws me a "System.NullReferenceException" in this line

lblDebug.Text += dataTable.Rows.Count +"";

and it seems like dataTable is 'null'.

Edit: I know what a NullReferenceException is, but why is it there? I mean it's a sample from the Json.Net page and how do I write the code correctly so I don't get the exception.

edited May 23 '15 at 13:29

asked May 23 '15 at 13:21

IrgendEineZecke

2

(The sample code works fine for me, btw. My guess is that `lblDebug` is null...) – Jon Skeet May 23 '15 at 13:28
1

Yep, works fine for me too: https://dotnetfiddle.net/l4AxdO – Andrew Whitaker May 23 '15 at 13:29
1

When it crashes, use the mouse to find what exactly is null. Assuming the code posted is the real code, `lblDebug` seems most likely – Ňɏssa Pøngjǣrdenlarp May 23 '15 at 13:30
lblDebug is not null, it has text in it. lblDebug.Text = "> "; – IrgendEineZecke May 23 '15 at 13:31
do you have a full stacktrace? should be printed to the console. otherwize check the inner exception property of the excepion. – Tim Hansson May 23 '15 at 13:35
I made a small video/gfy so you can see what I see: https://gfycat.com/LegitimateIllinformedHoneybee – IrgendEineZecke May 23 '15 at 13:36

Json.NET sample code keeps giving me a 'System.NullReferenceException'

0 Answers0