Client-side validation in custom validation attribute - asp.net mvc 4

Client-side validation in custom validation attribute - asp.net mvc 4

In ASP.NET MVC 5, you can implement client-side validation for a custom validation attribute using the jQuery Unobtrusive Validation library.

Here's an example:

  • Define a custom validation attribute that inherits from ValidationAttribute, and override its IsValid() method to perform the validation logic.
using System.ComponentModel.DataAnnotations; using System.Web.Mvc; public class CustomValidationAttribute : ValidationAttribute, IClientValidatable { protected override ValidationResult IsValid(object value, ValidationContext validationContext) { // Perform the validation logic here if (value == null) { return new ValidationResult("Value is null."); } return ValidationResult.Success; } public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context) { yield return new ModelClientValidationRule { ValidationType = "customvalidation", ErrorMessage = this.ErrorMessage }; } }

In this example, we define a custom validation attribute called CustomValidationAttribute that simply checks if the value is null. We also implement the IClientValidatable interface and override its GetClientValidationRules() method to provide the client-side validation rules for the attribute.

  • In your view, include the necessary scripts to enable client-side validation, such as:
<script src="~/Scripts/jquery-1.10.2.min.js"></script> <script src="~/Scripts/jquery.validate.min.js"></script> <script src="~/Scripts/jquery.validate.unobtrusive.min.js"></script>
  • Add the custom validation attribute to a property in your model, for example:
public class MyModel { [CustomValidation] public string MyProperty { get; set; } }
  • In your view, include a form that uses the Html.BeginForm() helper method, and include an input element for the property, for example:
@model MyModel @using (Html.BeginForm()) { @Html.LabelFor(m => m.MyProperty) @Html.TextBoxFor(m => m.MyProperty) @Html.ValidationMessageFor(m => m.MyProperty) <input type="submit" value="Submit" /> } @section Scripts { @Scripts.Render("~/bundles/jqueryval") <script> $.validator.addMethod("customvalidation", function (value, element, params) { return value != null; }); $.validator.unobtrusive.adapters.add("customvalidation", [], function (options) { options.rules["customvalidation"] = {}; options.messages["customvalidation"] = options.message; }); </script> }
  • Run your application, and the client-side validation should now work automatically for the property decorated with the custom validation attribute.

In this example, we add a custom client-side validation rule using the $.validator.addMethod() method, which checks if the value is not null. We then register the custom validation rule using the $.validator.unobtrusive.adapters.add() method, which maps the rule to the customvalidation validation type and sets the error message.

Note that the CustomValidationAttribute class should have a matching JavaScript method with the same validation type name ("customvalidation" in this case).

Examples

    using System.ComponentModel.DataAnnotations; using System.Web.Mvc; public class CustomValidationAttribute : ValidationAttribute, IClientValidatable { public CustomValidationAttribute() { ErrorMessage = "Custom validation error message."; } public IEnumerable<ModelClientValidationRule> GetClientValidationRules(ModelMetadata metadata, ControllerContext context) { yield return new ModelClientValidationRule { ErrorMessage = ErrorMessage, ValidationType = "customvalidation" }; } protected override ValidationResult IsValid(object value, ValidationContext validationContext) { // Custom validation logic here if (value != null && /* condition */) { return ValidationResult.Success; } return new ValidationResult(ErrorMessage); } } 
      // jQuery validation method for custom validation $.validator.unobtrusive.adapters.add("customvalidation", function (options) { options.rules["customvalidation"] = true; options.messages["customvalidation"] = options.message; }); $.validator.addMethod("customvalidation", function (value, element, params) { // Custom client-side validation logic here return /* validation result */; }, "Custom validation error message.");

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