Textbox text from background worker?

Question

I've been trying to figure out how to get my textbox's text or other property from within a background worker. Does anybody know how to do this? I cannot pass it as a param because it needs to be real-time. Thanks for the help!

Why doesn't your current code work? Do you get exceptions? If yes, what kind? — svick, Jul 05 '11 at 15:20
@Adrian apologies, I meant 'from within a background worker'. @svick in my current code I pass the text but by the time it gets to the part of the code were it uses the text, the text is old. So I need to get the text at the exact moment it is used from within the background worker. Hopefully this makes sense. — user556396, Jul 05 '11 at 15:31
http://stackoverflow.com/questions/142003/cross-thread-operation-not-valid-control-accessed-from-a-thread-other-than-the-t/142069#142069 — Bolu, Jul 05 '11 at 15:39

LarsTech · Accepted Answer · 2011-07-05T15:48:07.860

9

I think you need to just invoke the property (pseudo-code):

private void bgw1_DoWork(object sender, DoWorkEventArgs e)
{
  // looping through stuff
  {
    this.Invoke(new MethodInvoker(delegate { Text = textBox1.Text; }));
  }
}

edited Jul 05 '11 at 15:48

answered Jul 05 '11 at 15:38

LarsTech

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Thank you.. I was not aware it was that simple. – user556396 Jul 05 '11 at 15:44
5

I'm suppressed you didn't mention the exception *Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on.* in your question.. – Bolu Jul 05 '11 at 15:48

score 2 · Answer 2 · answered Jul 12 '13 at 12:16

2

Or if needed in WPF:

private void bgWorker_DoWork(object sender, DoWorkEventArgs e)
{
    string text = null;
    myTextBox.Dispatcher.Invoke(new Action(delegate()
    {
        text = myTextBox.Text;
    }));
}

answered Jul 12 '13 at 12:16

DeMama

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score 2 · Answer 3 · answered Jul 06 '11 at 06:31

2

Use the ReportProgress method and event of the Background worker. That will switch to the correct thread for you.

answered Jul 06 '11 at 06:31

Emond

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score 1 · Answer 4 · edited Jul 12 '13 at 12:34

i think you should use invoke method.

here's my example.

delegate void myDelegate(string name);
//...
private void writeToTextbox(string fCounter)
{
    if (this.InvokeRequired)
    {
        myDelegate textWriter = new myDelegate(displayFNums);
        this.Invoke(textWriter, new object[] { fCounter });
    }
    else
    {
        textbox1.Text = "Processing file: " + fileCounter + "of" + 100;
    }
}
//...

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    //...
    writeToTextbox(fileCounter.ToString());
}

in dowork i manipulate some textfile and i inform the user about how many files i have processed so far.

replace "displayFNums" with your actual method name "writeToTextbox" — dataCore, Dec 08 '14 at 16:48

Textbox text from background worker?

4 Answers4

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