Question

I have a couple of textboxes that will contain dates only. If one textbox has a date and the user tries to submit without entering a date in the other date textbox they will be stopped before submit. The way I want to do this is with the following javascript function:

function ClientValidate(sender, args) {
       // Get Both form fields
       var txtdate1 = document.getElementById('<%=txtdate1.ClientID%>');
       var txtdate2 = document.getElementById('<%=txtdate2.ClientID %>');

    // do you client side check to make sure they have something
       if (txtdate1.value != '' && txtdate2.value == '') {

        args.IsValid = false;
    }
    else
    {
        args.IsValid = true;
    }
    if (txtdate2.value != '' && txtdate1.value == '') {

        args.IsValid = false;

    }
    else {
        args.IsValid = true;
    }
}

The creation of the textboxes and date stuff is as follows.

Dim bttndate1 As New ImageButton
    bttndate1.ID = "bttndate1"

    Dim txtdate1 As New TextBox
    txtdate1.ID = "txtdate1"
    txtdate1.Width = 65

    Dim calex1 As New AjaxControlToolkit.CalendarExtender
    calex1.TargetControlID = "txtdate1"
    calex1.Format = "MM/dd/yyyy"
    calex1.PopupButtonID = "bttndate1"

    '**************** date box2 ***************

    Dim bttndate2 As New ImageButton
    bttndate2.ID = "bttndate2"
    bttndate2.Style.Add("cursor", "pointer")

    Dim txtdate2 As New TextBox
    txtdate2.ID = "txtdate2"
    txtdate2.Width = 65


    Dim calex2 As New AjaxControlToolkit.CalendarExtender
    calex2.TargetControlID = "txtdate2"
    calex2.Format = "MM/dd/yyyy"
    calex2.PopupButtonID = "bttndate2"

Here is the Validator

    Dim custval As New CustomValidator
    custval.ID = "ValidPage"
    custval.ClientValidationFunction = "ClientValidate"
    custval.ErrorMessage = "You Must Enter a 'From' Date and a 'To' Date"
    custval.ErrorMessage = "You Must Select a Vendor"
    custval.SetFocusOnError = True
    custval.ControlToValidate = "txtdate1"
    custval.EnableClientScript = True

MY problem is that the javascript isn’t finding the two textboxes because i create them in code
any ideas?

Answer 1

I’m an opponent of the ClientScriptManager. The solutions above will probably work, but an alternate method would be to declare a couple of variables in JavaScript outside of your ClientValidate() method.

var textdate1;
var textdate2;

Put a literal in your page somewhere (you can really put it anywhere as long as it has the runat=”server” attribute).

<asp:Literal ID="litJSVars" runat="server" />

Then in event where you’re creating the textboxes and stuff, add the following code:

this.litJSVars.Text = "textdate1 = document.getElementById('" + txtdate1.ClientID + "');\\n";
this.litJSVars.Text += "textdate2 = document.getElementById('" + txtdate2.ClientID + "');";

It isn’t better or worse than the ideas above, it’s just a different way of going about it.