Validating dynamically created textboxes

[davidrobin]

I am dynamically creating textboxes and for each textbox a custom validator control.
How do I link the validator control to the textbox so it can be Validated.

Thanks

[mendhak]

Each Validator has a ControlToValidate property, doesn't it?

[davidrobin]

It does but with the custom validator control you cannot reference it in code as it is not a physical control on the webform.
I have also not managed to linke any dynamically created validation control to a dynamically created textbox. For me it just doesn't work, so I am hoping others have had better success and can tell me how.

[mendhak]

I'll look into this when I get into work, can you show all the relevant code you have so far?

[Memnoch1207]

Example:

Public myTextBox As TextBox
Public myValidator As CustomValidator
 
myTextBox = New TextBox
 
myValidator = New CustomValidator
myValidator.ControlToValidate = myTextBox.ID

[nemaroller]

A dynamically created textbox does not have an ID until it is added to its container.

An easily missed clarification is - you have to set the ControlToValidate property only after the control you want to validate has been added to its container - otherwise it does have an ID, and you will get the infamous 'ControlToValidate cannot be set to nothing' error.

Public myTextBox As TextBox
Public myValidator As CustomValidator
 
myTextBox = New TextBox
 
myValidator = New CustomValidator
'TEXTBOX must be added to its container first
Controls.Add(myTextBox)
myValidator.ControlToValidate = myTextBox.ID

[davidrobin]

I am not at work at the moment but the way I am doing it is this.
This code is done from memory so there may be minor syntactic errors.

dim tr as new tablerow
        dim tc as new tablecell
 
        dim tb as new textbox
        tb.id = "txt1"
        tc.contols.add(tb)
        tr.cells.add(tc)
 
        tc=new tablecell
 
        dim cv as new customvalidator
        cv.controltovalidate = "txt1"
        tc.controls.add (cv)
 
        tr.cells.add(tc)
 
        table1.rows.add(tr)

As you can see I am creating an new textbox, giving it an ID then adding it to the table web control.

I wonder if the textbox retains the id I specify? I am presuming it does but it would be good to check that out.

Do you think the fact the controls are contained within a table makes any difference? I wouldn't have thought so.

[nemaroller]

Specificying an id probably won't make a difference. The framework normally appends the name of the control, or increments from control collection.

For instance, if the control was added to a panel...

pnl0_txt1

would be the clientid seen on the client-side.

Anyway, you just have to be sure to set the controlToValidate property after the controls have been added to the parent container - without which, how could the framework possibly know how to identify the controls? The framework must use the parent_child naming scheme mentioned above for postback and viewstate, so you can only accurately assign it after it has been added to the container.

The below code is in C#, but I think you can convert it to VB easily enough since its mostly .Net methods except the declarations.

private void Page_Load(object sender, System.EventArgs e)
{
CustomValidator validator;
Table table;
TableRow tr;
TableCell tc;
TextBox textbox;

textbox = new TextBox();			
validator = new CustomValidator();


tr = new TableRow();

tc = new TableCell();
tc.Controls.Add(textbox);
tr.Cells.Add(tc);

tc = new TableCell();
tc.Controls.Add(validator);
tr.Cells.Add(tc);

table = new Table();            
table.Rows.Add(tr);
//following line for this demonstration.. adds controls to the document.
Page.Controls[1].Controls.Add(table);

//now that the controls have been added to the parent
//container, you can properly assign the property. It is 
//only after the controls have been added, can the framework
//distinguish the naming scheme.

validator.ControlToValidate = textbox.ClientID;
}

[davidrobin]

Thanks for all your help, I am getting closer now but there are a few things I need to iron out.

I have a web form with a table and a button (web controls).
This is the code on the form.

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'Put user code to initialize the page here
 
 
        '****************************************************************
        '*
        '
        Dim tr As New TableRow
        Dim cell As New TableCell
 
        Dim t As New TextBox
 
        cell.Controls.Add(t)
        tr.Cells.Add(cell)
 
        cell = New TableCell
        cell.Text = "hello?"
        tr.Cells.Add(cell)
 
        cell = New TableCell
        Dim p As New CustomValidator
        cell.Controls.Add(p)
        tr.Cells.Add(cell)
 
        Table1.Rows.Add(tr)
 
        Table1.GridLines = GridLines.Both
 
        p.ControlToValidate = t.ClientID
 
        Response.Write(t.ClientID)
        Response.Write(p.ControlToValidate)
        Response.Write(p.ClientID)
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
 
        'Property does not exist
        'table1.Rows(0).Cells(2).Controls(0).isvalid
 
        'This does not work
        Dim c As New CustomValidator
        c = DirectCast(Table1.Rows(0).Cells(2).Controls(0), CustomValidator)
 
        Dim t As New TextBox
        t = DirectCast(Table1.Rows(0).Cells(0).Controls(0), TextBox)
 
        If t.Text <> "qwerty" Then
            c.IsValid = False
        Else
            c.IsValid = True
        End If
    End Sub

Now my problem is how to reference the custom validator so I can set the IsValid property to true/false. I can't do it this way

table1.Rows(0).Cells(2).Controls(0).isvalid

as the property does not exist, and trying it the other way above just does not work.

Another interesting thing is (Which is OK for me because I want a CustomValidator control) if you change the validator control to a requiredfieldvalidator control the page will not postback when you click the button. At least that is what happened to me.

So the question remains:
How can I set the IsValid property of a customValidator control created dynamically when a button is pressed?

I have attached the webform to save you copying and pasting code.