When we create applications that accept data from users, we must validate that data before storing it in a database. The .Net Framework not only provides validation attributes to simplify checks for required input, data types, value ranges, and patterns (e.g. email addresses and credit card numbers), but ASP.Net Core can check for validation errors in submitted HTML form values automatically.
A model state in ASP.Net Core is a collection of name-value pairs, along with validation information, that is sent to the server during a POST request. Any error messages included in the validation information are the model validation errors. The ApiController attribute introduced in ASP.Net Core 2.1 handles model state validation automatically. If the model state is invalid, it returns the appropriate error.
This article presents a discussion of how we can work with this new feature in ASP.Net Core.
Create an ASP.Net Core application in Visual Studio
In this section we will create the ASP.Net Core application we will use to learn how we can work with the ApiController attribute. Follow the steps outlined below to create a new ASP.Net Core project in Visual Studio 2017.