Split the requiredValidator into two validators. A boolean in .Net is always required, but can be set to false. To support validated but optional checkboxes we introduced the IsTrue validator.
- Required, to validate if a value is not
null,undefinedor empty-string. - IsTrue, to validate a value (for example a checkbox) is set to true.
If you use the [Required] or [RequiredAttribute] ValidationAttribute for required checkboxes please create an IsTrueAttribute based on ValidationAttribute