how to use custom validator for multiple controls?

Question

I have date fields and I want to validate if both the dates are selected or none. I have added the following customValidator

<asp:CustomValidator ID="CustomValidator3" runat="server" ErrorMessage="CustomValidator" Text="You must select both or no dates" ClientValidationFunction="dateValidate"  ValidateEmptyText="false" Font-Size="Small" Font-Bold="True" ForeColor="Red" SetFocusOnError="True"></asp:CustomValidator>

But it does not work if I am not adding customvalidator. My client side function is below. This method works fine otherwise when I am validating in date fields directly but I am trying to implement it using customvalidator.

    function dateValidate(sender, args) {

        var From = document.getElementById('dataContentplaceholder_wdpFrom').title;

        var To = document.getElementById('dataContentplaceholder_wdpTo').title;
        if (From.toString.length == 0 && To.toString.length >=1 || To.toString.length == 0 && From.toString.length >=1) {

            args.IsValid = false;
        }
        else {

            args.IsValid = true;
        }
    }

Answer 1

If the date fields are rendered as TextBoxes (I am not familiar with Infragistics), you could use a markup similar to this one:

<asp:TextBox ID="txtBox1" runat="server" onchange="ValidateTexts();" ... />
<asp:TextBox ID="txtBox2" runat="server" onchange="ValidateTexts();" ... />
<asp:CustomValidator ID="customValidator1" runat="server" Text="You must select both or no dates" ForeColor="Red" ClientValidationFunction="txtValidate"  ValidateEmptyText="true" ... />

With the following client-code:

function ValidateTexts() {
    ValidatorValidate(document.getElementById('<%= customValidator1.ClientID %>'));
}

function txtValidate(sender, args) {
    var from = document.getElementById('<%= txtBox1.ClientID %>').value;
    var to = document.getElementById('<%= txtBox2.ClientID %>').value;
    args.IsValid = (from.length == 0 && to.length == 0) || (to.length > 0 && from.length > 0);
}

The onchange event handler is called when a modified field loses focus. Without it, the validation is done only when a postback is triggered.