TextBox change Event in wpf Change Event

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Hello,
I am having a text box in wpf c# window application. I am creating it in c# dynamically in Data grid.I have attached a event handler to that text box.But problem is that when control is loaded into it the text box event is being called infinitely ...Complete code is being done in c# only... I am not using xaml ... every text box is being created dynamically.... Note: the text box is present in Data Grid... Please help me out yar...

C#

private void txtUnitCount_Changed(object Sender, TextChangedEventArgs e)
            {
          try
          {
              int index = 0;
              int rowIndex = -1;
              TextBox txt = Sender as TextBox;
              int Units = Convert.ToInt32(txt.Text);

              for (index = 1; index < dsBillingDetails.Tables.Count; index++)
               {
                DataRowCollection rowCol = dsBillingDetails.Tables[index].Rows;

               DataRow[] DataRows = dsBillingDetails.Tables[index].Select(find);
                  if (DataRows.Count() > 0)
                 {
                    DataRow foundRow = DataRows[0];

                     rowIndex = rowCol.IndexOf(foundRow);
                     if (rowIndex != -1)
                      {

                        //This line is causing problem i.e below line
                        dsBillingDetails.Tables[index].AcceptChanges();

                       }

                      break;
                      }
                  }


          }
          catch (Exception ex)
          {
          }
      }

Posted 22-Oct-13 20:11pm

jing567

Updated 22-Oct-13 20:49pm

v4

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Comments

Sergey Alexandrovich Kryukov 23-Oct-13 2:25am

Very good, now you need to create an extremely simplified but comprehensive code sample. Remove everything which is not related to this particular problem. Just one text box, probably no other controls, something like that. It's easy to screw up something in event handling, but such bugs are usually easy to spot. Add your sample code using "Improve question".
—SA

jing567 23-Oct-13 2:38am

Yes i will provide the code , but just now i have observed that the text change event is calling infinitely... this is because in the text change event i have updated the datable which is given as the source for Datagrid... so as the source of grid is updated... again text box event is being called... so like this this loop is becoming infinite... In few minute i will provide the code

Sergey Alexandrovich Kryukov 23-Oct-13 2:44am

I added formatting. Please, use "Improve question" again and 1) see how "pre" tags should be used for formatting code; 2) please improve your indentation to make the structure readable.

I have to sleep now, but for now I'm telling you what's really bad: exception handling. You block propagation of exceptions. Don't do it. Such construct is rarely used, very rarely, usually only to work around some "bad" library which is not accessible for your patch...

Also, your method does not show that it is used as an event handler, but probably it is. Show the code when an event handler is added to an invocation list of some event instance, to see what instance of what object. In other words, show where is your += operator.

—SA

jing567 23-Oct-13 2:47am

K please dont sleep... wait for 5 mins... I will update the code in couple of minutes

Sergey Alexandrovich Kryukov 23-Oct-13 2:50am

Sorry, no... tomorrow. Please leave me a comment when you are done.
—SA

jing567 23-Oct-13 2:54am

No man... I have tried almost to work out this one.... other wise let me know how to add handler to a text box for loast focus event thorugh c# in wpf... After waking up please look up the issue

db7uk 23-Oct-13 3:09am

Out of morbid curiosity, why not in xaml? have you tried creating a txtbox behavior and applying it to your control? also without the code which shows where you actually create the text box's it is hard to see what you are trying to do.

jing567 23-Oct-13 3:23am

Hi,
I cant create a text box in xaml as every elemnt on my screen should be dynamic and that too... I want to handle a to grasp the text box text entered by user in change event... and these text boxes are present in datagrid...and all components are formed dynamically only... and no xaml is used...

Sergey Alexandrovich Kryukov 23-Oct-13 12:26pm

Well, I must admit that not using XAML is quite viable approach in some cases. I only would advise to use XAML to provide basic layout only, and, on top of this, add controls programmatically as you do. Such combined design could be most effective in terms of development time, quality and maintainability.

Using just XAML can be mean a lot of tedious manual work with poorly readable results, poor maintainability. Besides, it won't help if one need variable number of controls.

—SA

Sergey Alexandrovich Kryukov 23-Oct-13 12:27pm

You still did not answer my question. Will you add += for event instance, to show that you added a handler, to what event of what object.
—SA

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Sergey Alexandrovich Kryukov · Accepted Answer · 2013-10-23T06:37:00

Please see my questions and clarify accordingly. For now, I'll answer to one of your follow-up questions:

jing111 wrote:
…let me know how to add handler to a text box for lost focus event…

Here is how:

C#

myElement.GotFocus += {sender, eventArgs} => {
    UIElement senderElement = (UIElement)sender;
    DoSomethingOnChangeOfTheFocusState(senderElement.IsFocused); // IsFocused will be true if got focus, false if lost
};

Note that the event name "GotFocus" is somewhat misleading. It actually covers both getting and losing focus. Same thing with the events UIElement.GotKeyboardFocus and UIElement.PreviewGotKeyboardFocus:
http://msdn.microsoft.com/en-us/library/system.windows.uielement.gotfocus%28v=vs.110%29.aspx[^],
http://msdn.microsoft.com/en-us/library/system.windows.uielement.gotkeyboardfocus%28v=vs.110%29.aspx[^],
http://msdn.microsoft.com/en-us/library/system.windows.uielement.previewgotkeyboardfocus%28v=vs.110%29.aspx[^].

The optional approach is to override corresponding virtual methods, with the same effect:
http://msdn.microsoft.com/en-us/library/system.windows.uielement.ongotfocus(v=vs.110).aspx[^],
http://msdn.microsoft.com/en-us/library/system.windows.uielement.ongotkeyboardfocus(v=vs.110).aspx[^],
http://msdn.microsoft.com/en-us/library/system.windows.uielement.onpreviewgotkeyboardfocus(v=vs.110).aspx[^].

—SA