Question

I wrote this code and I am trying to figure out what I have done wrong with the customValidator and I get this error. Could anyone help me with this.

In my form I have many radio buttons inside a repeater and I generate the radioButton.ID based on some unique fields that are coming from the database. Radiobuttons that belong to the same category are given the same GroupName like this:
(so my logic is that even if one RadioButton of that Group is selected, that group is validated)enter code here

radioButton.GroupName = dataRowTemp["QuestionID"].ToString() + dataRowTemp["ControlID"].ToString();

I have the following code in the code behind .aspx.cs file

CustomValidator customValidator = new CustomValidator();
customValidator.ControlToValidate = radioButton.ID;
customValidator.ClientValidationFunction = "checkRadiobuttonSelection";
customValidator.ValidateEmptyText = true;
customValidator.EnableClientScript = true;
e.Item.Controls.Add(customValidator);

and I have the following code in the .aspx file

<script type="text/javascript">
    function checkRadiobuttonSelection(oSrc, args) {
        args.IsValid = false;
        var element;
        var element2;
        var ctrlid = oSrc.id;
        var validatorid = document.getElementById(ctrlid);
        ctrlid = validatorid.controltovalidate;
        element2 = document.getElementById(ctrlid);
        for (var i = 0; i < document.forms[0].elements.length; i++) {
            element = document.forms[0].elements[i];
            if (element.type == "radio") {
                if (element.GroupName == element2.GroupName) {
                    if (element.checked == true) {
                        args.IsValid = true;
                    }
                }
            }
        }
    }       
</script>

When I execute the code, I get this error

[HttpException (0x80004005): Control '1' referenced by the ControlToValidate property of '' cannot be validated.]
   System.Web.UI.WebControls.BaseValidator.CheckControlValidationProperty(String name, String propertyName) +8757509
   System.Web.UI.WebControls.CustomValidator.ControlPropertiesValid() +35
   System.Web.UI.WebControls.BaseValidator.get_PropertiesValid() +21
   System.Web.UI.WebControls.BaseValidator.OnPreRender(EventArgs e) +27
   System.Web.UI.Control.PreRenderRecursiveInternal() +80
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +842

Any pointers for me? Thank you.

I have a similar code for text boxes, which works fine and validates the text boxes neatly.

Text Boxes code which works fine

.aspx.cs

CustomValidator customValidator = new CustomValidator();
customValidator.ControlToValidate = textBox.ID;
customValidator.ClientValidationFunction = "changeColorofTextBox";
customValidator.ValidateEmptyText = true;
customValidator.EnableClientScript = true;
e.Item.Controls.Add(customValidator);

.aspx

<script type="text/javascript">
    function changeColorofTextBox(oSrc, args) {
        if (args.Value.length > 0) {
            args.IsValid = true;
        }
        else {
            var ctrlid = oSrc.id;
            var validatorid = document.getElementById(ctrlid);
            ctrlid = validatorid.controltovalidate;
            document.getElementById(ctrlid).style.backgroundColor = "Tomato";
            args.IsValid = false;
        }
    }
</script>

Answer 1

You can’t use ControlToValidate with radio buttons. You need to look into creating a custom validator, for which this answer should help.