Configuring and using validation

In this recipe, you will learn how to configure and use client-side validation with jQuery, and server-side validation with C#.

Getting ready

We will create an ASP.NET Core MVC Web Application template by going to File | New | Project | AspNet Core Web Application.

How to do it...

1. First of all, let's create a class with validation attributes. These attributes will be used on both the client side and the server side:

public class ProductViewModel
{
  public int Id { get; set; }
  [Required]
  [RegularExpression(@"^[a-zA-Z]{1,40}$",
  ErrorMessage = "The field must be a string")]
  public string Name { get; set; }
  [Required]
  [Range(0.01, double.MaxValue,
  ErrorMessage = "Please enter a positive number")]
  public decimal Price { get; set; }
}

2. In addition to this, we will create a form in order to post the ProductViewModel. This is the Form version of  TagHelpers:

<form asp-controller="Home" asp-action="AddProduct" method="post" asp-antiforgery="true">
...