Model Validation In ASP.NET MVC Core 3.1

In this article we will understand the concept of model validation in ASP.NET MVC core 3.1. It is valid for any version of MVC core. These validations are available in System.ComponentModel.DataAnnotations namespace. Validation attributes let us specify validation rules for model properties. Model state represents errors that come from two sub systems' model binding and model validation.

There are in-built attributes in ASP.NET MVC core,

Attribute	Description
CreditCard	This validates that the property has a credit card format.
Compare	This attribute validates that two property in model class match like password and compare password.
EmailAddress	This validates the property has email address format.
Phone	This validates that the property has a telephone number format.
Range	This validates that the property value within a specified range.
RegularExpression	This validates that the property value matches a specified regular expression.
Required	This validates that the field is not null
StringLength	This validates that a string property value doesn't exceed a specified length limit.
Url	This validates that the property has a URL format.
Remote	This validates input on the client by calling an action method on the server

Start-up Visual Studio 2019. Now click on create new project and Choose ASP.NET Core Web Application and click on “Next”

After clicking next, another wizard will open. Under the project name, give a meaningful name to your project and click on create.

That will open up another new wizard. Select ASP.Net Core 3.0 from the dropdown. If not, select default. Choose Web Application (Model-View-Controller) template and click on create which will create ASP.Net Core Application.

Now right click on Models folder and “Add” class and name it Student.

Now open HomeController which is added when we created new project. Write the following code for Index and New IActionResult methods.