Sitecore CustomValidator does not fire on WFFM custom field

Question

I've try to extend SingleLineText field on WFFM on Sitecore. This field will have CustomValidator. But ServerValidate event does not fire when page postbacked. The snipped code below.

public class SingleLineText : Sitecore.Form.Web.UI.Controls.SingleLineText
{
   protected override void OnInit(EventArgs e)
   {
       base.OnInit(e);

       var validator = new CustomValidator() { Display = ValidatorDisplay.None };
       validator.ServerValidate += this.Validator_ServerValidate;
       this.generalPanel.Controls.Add(validator);
    }
    protected void Validator_ServerValidate(object source, ServerValidateEventArgs args)
    {
         // does not fire
         var validator = source as IValidator;
         args.IsValid = this.IsValid(validator);
    }
}

The same code works fine on ustom user control field which has ascx.

Answer 1

You will want to move your validation code to a new class that implements FormCustomValidator.

public class MySingleLineTextValidator : FormCustomValidator
{ 
    protected override bool EvaluateIsValid()
    {
        if (!String.IsNullOrEmpty(base.ControlToValidate))
        {
            Control controlToValidate = this.FindControl(base.ControlToValidate);
            //Code to validate
        }

        return false;
    }}

Then you will need add a BaseValidator Item in the WFFM Validation Folder, usually this path; /sitecore/system/Modules/Web Forms for Marketers/Settings/Validation. Add the assembly and class to the item.

Now against your custom Field, add the your new BaseValidator item in the Validation field and that's it.

See this post of a wffm custom form validator for a full example