event detection between different controls vb - vb.net

Question

I have a class A which contains 2 user controls declared as
Friend WithEvents CustInfo1 As WindowsApplication1.CustInfo
Friend WithEvents ServiceLocation1 As WindowsApplication1.ServiceLocation
Both have textBoxes. If value of textBoxA in custInfo1 changes then how can I make value of textBoxB in SeviceLocation1 also change
I will be most thankful if anyone can help me.
Thanks

Answer 1

You need to do the following:
Inside the CustInfo user control, you need to write code inside the textBoxA Changed event that raises an event from the CustInfo user control (e.g. TextBoxChanged event). RaiseEvent statement
Inside the ServiceLocation user control, create a public property getter and setter for whatever your textBoxB.Text is
On the form that contains both user controls, create code in the new CustInfo TextBoxChanged event and set the new property on the ServiceLocation1 user control.

Answer 2

All controls (also custom controls) have the property Controls, through which you can access the (sub) controls of that control. Now you can retrieve your textbox by calling the .Item(key) method on it. Then you can assign a event handler to it in your form or class.
Dim key As String = "textBoxA" 'Or simply the name of that TextBox in your CustInfo
Dim textboxA As TextBox = CustInfo1.Controls.Item(key)
AddHandler textBoxA.TextChanged, AddressOf mytextchangedhandler
Where that mytextchangedhandler handles the TextChanged event for that TextBox.
Personally I don't like this method too much, as you are relying on knowing either the name of the TextBox or the index in the Controls list of your usercontrol.
I would definitely go for the option to create your own event on your usercontrol. It is quite easy to do even! Below how to do it. In the code behind of your usercontrol, you'll have to add an event declaration:
Event MyTextBoxChanged(sender As Object, e As EventArgs)
Now we'll have to raise it, we do this by implementing the TextChanged event of the TextBoxA in your usercontrol (as you explained you wanted to do):
Private Sub TextBoxA_TextChanged(sender As System.Object, e As System.EventArgs) Handles TextBoxA.TextChanged
RaiseEvent MyTextBoxChanged(Me, EventArgs.Empty)
End Sub
Now we can simply implement this event (MyTextBoxChanged) in your Form as follows:
Private Sub CustInfo1_MyTextBoxChanged(sender As System.Object, e As System.EventArgs) Handles CustInfo1.MyTextBoxChanged
' Do something
End Sub
Obviously we still need to get the updated text, now we can create our own EventArgs that will give us the new (and/or old value) as you will want to have. We simply can inherit the System.EventArgs class and add some properties (for example a property OldText that holds the old text value and a property NewText that holds the new text value):
Public Class MyEventArgs
Inherits System.EventArgs
Private _OldText As String
Public ReadOnly Property OldText() As String
Get
Return _OldText
End Get
End Property
Private _NewText As String
Public ReadOnly Property NewText() As String
Get
Return _NewText
End Get
End Property
Public Sub New(oldText As String, newText As String)
_OldText = oldText
_NewText = newText
End Sub
End Class
Now we have to change the event definition and raising to use the MyEventArgs:
Event MyTextBoxChanged(sender As Object, e As MyEventArgs)
Private Sub TextBoxA_TextChanged(sender As System.Object, e As System.EventArgs) Handles TextBoxA.TextChanged
RaiseEvent MyTextBoxChanged(Me, New MyEventArgs(TextBoxA.Text))
End Sub
And also change the implementation in your Form:
Private Sub CustInfo1_MyTextBoxChanged(sender As System.Object, e As MyEventArgs) Handles CustInfo1.MyTextBoxChanged
MessageBox.Show(e.Text)
End Sub
More information about events can be found on our favorite spot MSDN.