[RESOLVED] user defined property

[athar_anis]

Dear All,
I have derived a textbox. This user control works fine everywhere. However, i have added a property in this as follow:

    
Public _propertyValue As Boolean
    Public Overridable Property AllowNull() As Boolean
        Get
            Return _propertyValue

        End Get
        Set(ByVal value As Boolean)
            _propertyValue = value
        End Set
    End Property

The reason behind this property is very simple. I want myself to be able to set this property of the textbox to TRUE if the value that is to be saved in the database can be null or not. If it is FALSE, then i will restrict the user to enter something in the textbox first. This also works fine. At design time, i can select True/False from the property.

Now, here is the problem. I am working in a MDI environment, therefore, i want to check all the textboxes with FALSE option selected for AllowNull property before saving the data.

I have written this piece of code:

    Public Function checkAllTextBoxes() As Boolean
        Dim ctrl As Control
 
        For Each ctrl In Me.ActiveMdiChild.Controls
            If TypeOf ctrl Is MyTextBox.mytextbox Then
              'NOW I WANT TO ACCESS THE PROPERTY ALLOWNULL HERE
              'LIKE THIS.
                If ctrl.allowNull = false Then
                'However, it only shows me the default textbox properties like allowdrop etc.
                   
                End If
            End If


        Next
    End Function

how do i make user defined property global and accessible through this code, what am i doing wrong here?

[jmcilhinney]

'However, it only shows me the default textbox properties like allowdrop etc.

It's not showing you the deafult TextBox properties. It's showing you the members of the Control class, because that's what type the 'ctrl' variable is.

Either:

If TypeOf ctrl Is MyTextBox Then
    Dim mtb As MyTextBox = DirectCast(ctrl, MyTextBox)

or:

Dim mtb As MyTextBox = TryCast(ctrl, MyTextBox)
 
If mtb IsNot Nothing Then

The first option checks the type first and only casts if the control is the correct type. You know that cast will work so DirectCast is used.

The second option attempts a cast and only uses the result if it's not Nothing. If the result is Nothing then that means that the cast failed because the control was not that type.

By casting you are telling the compiler that the object is that type so it's safe to make the assignment. Once you have a variable of type MyTextBox you can access the members of the MyTextBox type.

[athar_anis]

thanks a lot...
the first method worked like a charm