In this article I will explain with an example, how to perform Client Side validation for CheckBox in ASP.Net MVC Razor using jQuery.
The Client Side validations will be performed using Model class and Custom Data Annotation attributes.
 
 
Configuring Bundles and enabling Client Side validations
Please refer the following article for complete information on how to configure Bundles and enable Client Side validation in ASP.Net MVC project.
Using Bundles (ScriptBundle) in ASP.Net MVC Razor
Note: By default the validation done using Data Annotation attributes is Server Side. And hence to make it work Client Side, the Client Side validation must be enabled.
 
 
Custom Validation Data Annotations Attribute for CheckBox
The Required Data Annotation attribute does not work for Boolean validation i.e. performing validation Checked or Unchecked for a CheckBox.
Hence a new class will be created for developing Custom Validation Data Annotations Attribute for CheckBox. This attribute will validate the CheckBox as Boolean validation i.e. only two values True or False and will raise error when the value is False.
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.Web;
using System.Web.Mvc;
 
public class CheckBoxRequired : ValidationAttribute, IClientValidatable
{
    public override bool IsValid(object value)
    {
        if (value isbool)
        {
            return (bool)value;
        }
 
        return false;
    }
 
    public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
    {
        yield return new ModelClientValidationRule
        {
            ErrorMessage = FormatErrorMessage(metadata.GetDisplayName()),
            ValidationType = "checkboxrequired"
        };
    }
}
 
 
Model
The following Model class consists of one property TermsConditions to which the CheckBoxRequired Custom Data Annotation attribute has been applied.
As per MSDN, the Data Annotations attributes cause MVC to provide both client and server validation checks with no additional coding required by you. The Data Annotations attributes can be used with the Entity Data Model (EDM), LINQ to SQL, and other data models.
The CheckBoxRequired Custom Data Annotation has been specified with a property Error Message with a string value. As the name suggests, this string value will be displayed to the user when the validation fails.
public class PersonModel
{
    [Display(Name = "I accept the above terms and conditions.")]
    [CheckBoxRequired(ErrorMessage = "Please accept the terms and condition.")]
    public bool TermsConditions { get; set; }
}
 
 
Controller
The Controller consists of two Action methods.
Action method for handling GET operation
Inside this Action method, simply the View is returned.
 
Action method for handling POST operation
This action method handles the POST operation and when the form is submitted, the object of the PersonModel class is sent to this method.
public class HomeController : Controller
{
    // GET: Home
    public ActionResult Index()
    {
        return View();
    }
 
    [HttpPost]
    public ActionResult Index(PersonModel person)
    {
        return View();
    }
}
 
 
View
Inside the View, in the very first line the PersonModel class is declared as Model for the View.
The View consists of an HTML Form which has been created using the Html.BeginForm method with the following parameters.
ActionName – Name of the Action. In this case the name is Index.
ControllerName – Name of the Controller. In this case the name is Home.
FormMethod – It specifies the Form Method i.e. GET or POST. In this case it will be set to POST.
Inside the View, the following three HTML Helper functions are used:-
1. Html.CheckBoxFor – Creating a CheckBox for the Model property.
2. Html.LabelFor – Displaying the Model property name.
3. Html.ValidationMessageFor – Displaying the Validation message for the property.
There is also Submit button which when clicked, the Form gets submitted.
The jQuery and the jQuery Validation script bundles are rendered at the end of the Model using the Scripts.Render function.
Finally in order to make the CheckBoxRequired Custom Data Annotation validation to work on Client Side, the validation rule needs to be added to the jQuery Unobtrusive Validation Adapters.
@model CheckBox_Validation_MVC.Models.PersonModel
 
@{
    Layout = null;
}
 
<!DOCTYPE html>
 
<html>
<head>
    <meta name="viewport" content="width=device-width"/>
    <title>Index</title>
    <style type="text/css">
        body {
            font-family: Arial;
            font-size: 10pt;
        }
 
        .error {
            color: red;
        }
    </style>
</head>
<body>
    @using (Html.BeginForm("Index", "Home", FormMethod.Post))
    {
        <table>
            <tr>
                <td>@Html.CheckBoxFor(m => m.TermsConditions)</td>
                <td>@Html.LabelFor(m => m.TermsConditions)</td>
            </tr>
            <tr>
                <td></td>
                <td>
                    @Html.ValidationMessageFor(m => m.TermsConditions, "", new { @class = "error" })
                </td>
            </tr>
            <tr>
                <td></td>
                <td><input type="submit" value="Submit"/></td>
            </tr>
        </table>
    }
 
    @Scripts.Render("~/bundles/jquery")
    @Scripts.Render("~/bundles/jqueryval")
    <script type="text/javascript">
        (function ($) {
            $.validator.unobtrusive.adapters.addBool("checkboxrequired", "required");
        }(jQuery));
    </script>
 </body>
</html>
 
 
Screenshot
Client Side CheckBox validation in ASP.Net MVC Razor using jQuery
 
 
Downloads
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