MVC3: make checkbox required via jQuery validate?

Question

I want my \"Agree To Terms\" checkbox to be mandatory using jQuery validate, in an MVC3 project. I currently get server/client DRY/SPOT validation from \"MS data annotation

Answer 1

I've summarized here the correctly-working source code, which resulted from applying the accepted answer. Hope you find it useful.

RequiredCheckbox.aspx

<%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage" %>




    
    
    
    
    


    

        <% 
        // These directives can occur in web.config instead
        Html.EnableUnobtrusiveJavaScript();
        Html.EnableClientValidation();
        using (Html.BeginForm())
        { %>
            <%: Html.CheckBoxFor(model => model.IsTermsAccepted)%>
            <%: Html.ValidationMessageFor(model => model.IsTermsAccepted)%>

            <%: Html.TextBoxFor(model => model.ContactName)%>
            <%: Html.ValidationMessageFor(model => model.ContactName)%>
            Submit
        <% } %>
    

RegistrationViewModel.cs

using System;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;

public class RegistrationViewModel {
    [Mandatory (ErrorMessage="You must agree to the Terms to register.")]
    [DisplayName("Terms Accepted")]
    public bool isTermsAccepted { get; set; }

    [Required]
    [DisplayName("Contact Name")]
    public string contactName { get; set; }
}

MandatoryAttribute.cs

using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Web.Mvc;

public class MandatoryAttribute : ValidationAttribute, IClientValidatable
{
    public override bool IsValid(object value)
    {
        return (!(value is bool) || (bool)value);
    }
    public IEnumerable GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
    {
        ModelClientValidationRule rule = new ModelClientValidationRule();
        rule.ErrorMessage = FormatErrorMessage(metadata.GetDisplayName());
        rule.ValidationType = "mandatory";
        yield return rule;
    }
}