Conditional Custom Validation on 2 TextBoxes

Question

My goal here is to build a field that will basically make one or the other textbox required. I.E. If one textbox has some value that is not null, whitespace. or empty, I want the submit button to proceed. Else I want the standard red error to stop the submit from postingback and launching the insert function. I have tried writing this, but so far no good. What can I do to make this work?

 <script type="text/javascript">
                        function validateText(sender, args) {
                            if (args.value !== "") {
                                var textBoxB = document.getElementById('TextBox12');
                                args.IsValid = (TextBox12.value !== "");
                            }
                            return;

                            /*
                            if (!string.IsNullOrEmpty(TextBox12.Text + TextBox13.Text)) {
                               args.IsValid = true;
                            }
                            else {
                                if (string.IsNullOrEmpty(TextBox12.Text) && !string.IsNullOrEmpty(TextBox13.Text)) {
                                    args.IsValid = true;
                                }
                                else if (string.IsNullOrEmpty(TextBox13.Text) && !string.IsNullOrEmpty(TextBox12.Text)) {
                                    args.IsValid = true;
                                }
                                else {
                                    args.IsValid = false;
                                }
                            }
                            */

                        }
                    </script>
                    <div>
                        <div class="left">
                            <asp:Label ID="Label13" runat="server" Text="Advanced Cancellation:"></asp:Label>
                        </div>
                        <div class="right">
                            <asp:TextBox ID="TextBox12" runat="server"></asp:TextBox>
                            <asp:CustomValidator ID="CustomValidator1" runat="server" 
                                ErrorMessage="Required"
                                ValidationGroup='valGroup1' 
                                ClientValidationFunction="validateText"
                                OnServerValidate="ServerValidation"
                                ForeColor="Red"
                                ValidateEmptyText="true">
                            </asp:CustomValidator>
                            <asp:RegularExpressionValidator ID="RegularExpressionValidator2" runat="server" 
                                ErrorMessage="Advanced Cancellation must be an integer." 
                                ControlToValidate="TextBox12"
                                ValidationExpression="^\+?(0|[1-9]\d*)$"
                                ForeColor="Red">
                            </asp:RegularExpressionValidator>

                        </div>
                    </div>
                    <div>
                        <div class="left">
                            <asp:Label ID="Label14" runat="server" Text="Action Required (yyyy-MM-dd):"></asp:Label>
                        </div>
                        <div class="right">
                            <asp:TextBox ID="TextBox13" runat="server"></asp:TextBox>
                            <asp:CustomValidator ID="CustomValidator2" runat="server" 
                                ValidationGroup='valGroup1'
                                ValidateEmptyText="true"
                                ErrorMessage="Required" 
                                ClientValidationFunction="validateText"
                                OnServerValidate="ServerValidation"
                                ForeColor="Red">
                            </asp:CustomValidator>
                            <asp:CompareValidator
                                ID="CompareValidator1" runat="server"
                                Type="Date"
                                Operator="DataTypeCheck"
                                ControlToValidate="TextBox13"
                                ErrorMessage="Please enter a valid date."
                                ForeColor="Red">
                            </asp:CompareValidator>
                        </div>
                    </div>
protected void ServerValidation(object source, ServerValidateEventArgs args)
    {
        if (!string.IsNullOrEmpty(TextBox12.Text))
            args.IsValid = !string.IsNullOrEmpty(TextBox13.Text);

    }

That's what I have so far.

Answer 1

I have remove javascript code.Now your design part is

<div>
    <div class="left">
        <asp:Label ID="Label13" runat="server" Text="Advanced Cancellation:"></asp:Label>
    </div>
    <div class="right">
        <asp:TextBox ID="TextBox12" runat="server"></asp:TextBox>
        <asp:CustomValidator ID="CustomValidator1" runat="server"
            ErrorMessage="Required"
            ValidationGroup="valGroup1"
            OnServerValidate="ServerValidation"
            ForeColor="Red"
            ValidateEmptyText="true">
        </asp:CustomValidator>
        <asp:RegularExpressionValidator ID="RegularExpressionValidator2" runat="server"
            ErrorMessage="Advanced Cancellation must be an integer."
            ControlToValidate="TextBox12"
            ValidationExpression="^\+?(0|[1-9]\d*)$"
            ForeColor="Red">
        </asp:RegularExpressionValidator>

    </div>
</div>
<div>
    <div class="left">
        <asp:Label ID="Label14" runat="server" Text="Action Required (yyyy-MM-dd):"></asp:Label>
    </div>
    <div class="right">
        <asp:TextBox ID="TextBox13" runat="server"></asp:TextBox>
        <asp:CustomValidator ID="CustomValidator2" runat="server"
            ValidationGroup="valGroup1"
            ValidateEmptyText="true"
            ErrorMessage="Required"
            OnServerValidate="ServerValidation"
            ForeColor="Red">
        </asp:CustomValidator>
        <asp:CompareValidator
            ID="CompareValidator1" runat="server"
            Type="Date"
            Operator="DataTypeCheck"
            ControlToValidate="TextBox13"
            ErrorMessage="Please enter a valid date."
            ForeColor="Red">
        </asp:CompareValidator>
    </div>
</div>
    <div>
        <asp:Button ID="btnok" runat="server" ValidationGroup="valGroup1" />
    </div>

and code behind is

protected void ServerValidation(object source, ServerValidateEventArgs args)
    {
        if (!string.IsNullOrEmpty(TextBox12.Text) || !string.IsNullOrEmpty(TextBox13.Text))
            args.IsValid = true;
        else
        { 
            args.IsValid = false;
        }

    }

I have tested its work for me