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• Field Validating It is useful for validating textbox, comboBox... when user input - using the Valid

Field Validating It is useful for validating textbox, comboBox... when user input - using the Valid

Field Validating It is useful for validating textbox, comboBox... when user input - using the Validating procedure - using a simple for loop

Rate Field Validating It is useful for validating textbox, comboBox... when user input - using the Valid

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System.ComponentModel.CancelEventArgs) Handles TextBox2.Validating 
Dim tBox As TextBox = DirectCast(sender, TextBox) 
'Your validation code goes here. 
If (tBox.Text = "ok") Then 
  e.Cancel = False 
Else 
  e.Cancel = True 
End If 
End Sub 
 
======================================================== 
 The following is a dynamic way to validate more than one fields 
\\\ 
Dim last As String 

Private Sub Form1_Load(ByVal sender As Object, _ 
ByVal e As System.EventArgs) Handles MyBase.Load 
   doset(Me) 
End Sub 

Private Sub doSet(ByVal parentCtr As Control) 
Dim ctr As Control 
For Each ctr In parentCtr.Controls 
  AddHandler ctr.LostFocus, AddressOf meLostFocus 
  AddHandler ctr.GotFocus, AddressOf meGotFocus 
  doSet(ctr) 
Next 
End Sub 

Private Sub meLostFocus(ByVal sender As Object, _ 
ByVal e As System.EventArgs) 
last = DirectCast(sender, Control).Name 
End Sub 

Private Sub meGotFocus(ByVal sender As Object, _ 
ByVal e As System.EventArgs) 
DirectCast(sender, Control).Text = last 
End Sub 
/// 

 
=======================================================
 
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles Button1.Click 
  CheckIfDirty(Me.Controls) 
End Sub 

Private Sub CheckIfDirty(ByVal ctrls As Control.ControlCollection) 
For Each ctrl As Control In ctrls 
 If TypeOf ctrl Is TextBox Then 
  If DirectCast(ctrl, TextBox).Modified Then 
   Dim strOut As String 
   strOut = String.Format("{0} is dirty", DirectCast(ctrl, TextBox).Name) 
   Trace.WriteLine(strOut) 
  End If 
 End If 

'check child controls if any 
 CheckIfDirty(ctrl.Controls) 
Next 
End Sub 

==================================================
 private void MyValidatingCode()
      {
         // Confirm there is text in the control.
         if (textEmail.Text.Length == 0)
         {
            throw new Exception("Email address is a required field.");
         }
         // Confirm that there is a "." and an "@" in the e-mail address.
         else if(textEmail.Text.IndexOf(".") == -1 || textEmail.Text.IndexOf("@") == -1)
         {
            throw new Exception("Email address must be valid e-mail address format." +
             "\nFor example: '[email protected]'");
         }
      }

// Validate the data input by the user into textEmail.
private void textEmail_Validating(object sender, System.ComponentModel.CancelEventArgs e)
{ 
 try
   {
    MyValidatingCode();
   }
 catch(Exception ex)
   {
     // Cancel the event and select the text to be corrected by the user.
        e.Cancel = true;
        textEmail.Select(0, textEmail.Text.Length);
     // Set the ErrorProvider error with the text to display. 
        this.errorProvider1.SetError(textEmail,ex.Message);
    }
  }   
  private void textEmail_Validated(Object sender, System.EventArgs e)
  {
    //If all conditions have been met, clear the error provider of errors.
      errorProvider1.SetError(textEmail, "");
  }