Book Image

Blazor WebAssembly by Example

By : Toi B. Wright
Book Image

Blazor WebAssembly by Example

By: Toi B. Wright

Overview of this book

Blazor WebAssembly makes it possible to run C# code on the browser instead of having to use JavaScript, and does not rely on plugins or add-ons. The only technical requirement for using Blazor WebAssembly is a browser that supports WebAssembly, which, as of today, all modern browsers do. Blazor WebAssembly by Example is a project-based guide for learning how to build single-page web applications using the Blazor WebAssembly framework. This book emphasizes the practical over the theoretical by providing detailed step-by-step instructions for each project. You'll start by building simple standalone web applications and progress to developing more advanced hosted web applications with SQL Server backends. Each project covers a different aspect of the Blazor WebAssembly ecosystem, such as Razor components, JavaScript interop, event handling, application state, and dependency injection. The book is designed in such a way that you can complete the projects in any order. By the end of this book, you will have experience building a wide variety of single-page web applications with .NET, Blazor WebAssembly, and C#.
Table of Contents (11 chapters)

Using the validation components

Input validation is an important aspect of every application since it prevents users from entering invalid data. The Blazor WebAssembly framework uses data annotations for input validation. There are over 30 built-in data annotation attributes. This is a list of the ones that we will be using in this project:

  • Required: This attribute specifies that a value is required. It is the most commonly used attribute.
  • Display: This attribute specifies the string to display in error messages.
  • MaxLength: This attribute specifies the maximum string length allowed.
  • Range: This attribute specifies the numeric range constraints of the value.

The following code demonstrates the use of a few data annotations:

[Required]
public DateTime? Date { get; set; }
[Required]
[Range(0, 500, ErrorMessage = "The {0} field must be < {2}.")]
public decimal? Amount { get; set; }

There are two built-in validation components:

  • ValidationSummary...