Question

Additional information: Object reference not set to an instance of an object.

I have this code

DotTeachDataSet ds;
DotTeachDataSetTableAdapters.QuestionsTableAdapter ta;

private void button1_Click(object sender, RoutedEventArgs e)
{                                         
    ta.CreateQuestion(discussionQuestion.Text, webPage.Text, choiceA.Text, choiceB.Text, choiceC.Text, choiceD.Text, hint.Text, rightAnswerCbox.Uid);
    ta.Fill(ds.Questions);
}

That Im using to try to get the values from text boxes in a xaml and send them to a data base but I keep getting the error:

An unhandled exception of type
‘System.NullReferenceException’
occurred in DotTeach.exe

Additional information: Object
reference not set to an instance of an
object.

and visual studio highlights the line

ta.CreateQuestion(discussionQuestion.Text, webPage.Text, choiceA.Text, choiceB.Text, choiceC.Text, choiceD.Text, hint.Text, rightAnswerCbox.Uid);

Does anyone have any ideas what i could try?

I got rid of the error message but it’s still not doing what I need it to do. I’m trying to get it to add data to a database when the button is clicked. Heres the function I’m using thats not working

private void button1_Click(object sender, RoutedEventArgs e)
    {
        DotTeach.DotTeachDataSet dotTeachDataSet = ((DotTeach.DotTeachDataSet)(this.FindResource("dotTeachDataSet")));
        DotTeach.DotTeachDataSetTableAdapters.QuestionsTableAdapter dotTeachDataSetQuestionsTableAdapter = new DotTeach.DotTeachDataSetTableAdapters.QuestionsTableAdapter();


        //ADD THE QUESTION TO THE DATA BASE
        dotTeachDataSetQuestionsTableAdapter.CreateQuestion(discussionQuestion.Text, webPage.Text, choiceA.Text, choiceB.Text, choiceC.Text, choiceD.Text, hint.Text, rightAnswer.Text);
    }

I’m not even sure what else to try.

Answer 1

Well, to get a NullReferenceException, one of the following is null:

• ta
• discussionQuestion
• webPage
• choiceA
• choiceB
• choiceC
• choiceD
• hint
• rightAnswerCbox

My guess would be ta, but you should be able to find that out either with logging or in the debugger. What’s meant to be assigning a non-null value to ta?

Is this always failing (in which case it’ll be easy to diagnose) or only sometimes?