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Data Validation in ASP.NET MVC


Data Validation in ASP.NET MVC

In this article, we will learn how to implement data validations in the ASP.NET MVC application.
In our previous article, we have created an application that performs Create, Edit, Delete and Details operations that generate views for each of the operations.
We will create new class called Blog and will implement data validation in the class properties, which will display validation messages on the click of Save button without data, as shown below in the image below.

Error Message

Blog Class

In the above image, we created a class named Blog with data validation through data Annotation.

DataAnnotations

ASP.NET MVC uses DataAnnotations attributes to implement validations. DataAnnotations includes built-in validation attributes for different validation rules, which can be applied to the properties of model class. ASP.NET MVC framework will automatically enforce these validation rules and display validation messages in the view.
The DataAnnotations attributes included in System.ComponentModel.DataAnnotations namespace. The following table lists DataAnnotations validation attributes.
Attribute
Description
Required
Indicates that the property is a required field
StringLength
Defines maximum length for string field
Range
Defines minimum and maximum value for a numeric field
RegularExpression
Speicifies the field value must match with speicified Regular expression
CreditCard
Speci
Specifies that the specified field is a credit card number
CustomValidation
Specifies custom validation method to validate the field
EmailAddress
Validates with email address format
FileExtension
Validates with File extension
MaxLength
Specifies maximum length for a string field
MinLength
Sepcifies minimum length for a string field
Phone
Specifies that the field is  a phone number using regular expression for phone number

Implementing Validation to our Blog Class

Apply DataAnnotation attributes to the properties of our Blog class as shown below


Here, we have made the Title property of the blog class as compulsory by decorating it with Required attribute with error to be displayed in case of irregularities.

The DatePosted property is decorated with two attributes to make it compulsory and display in Calendar Date picker as shown below

Date Error

Save the project and create a controller with scaffolding to generate the Create and Edit methods and View pages as shown below
Controller

Run the application and see that data validation is properly enforced by the system as can be seen below
Edit Error

The view page provides the ValidationMessage HTML helper method for error messages display as can be seen below
Validation Message

Thank you  



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