Razor View Engine

What is a View Engine?

A View Engine is an MVC subsystem that uses its markup syntax. It is in charge of turning the server-side template into HTML markup and rendering it in the browser. Initially, ASP.NET MVC includes one view engine, web forms (ASPX), but with ASP.NET MVC3, a new view engine, Razor, is introduced. ASP.NET MVC also supports different view engines such as Spark and NHaml.

Working of View Engine

Each view engine consists of three key components:

1. ViewEngine class: The ViewEngine class is in charge of locating view templates and implementing the IViewEngine interface.
2. View class: This class implements the IView interface and is responsible for mixing the template with data from the current context before converting it to output HTML content.
3. Template parsing engine: This engine parses the template and converts the view to executable code.

Why is the View Engine required in ASP.NET MVC?

• The view engine is responsible for producing HTML for View.
• It turns HTML+Programming language into just HTML.
• It is used to determine the appropriate view for the action method.
• It is used to locate a View within the shared folder.
• We used to write C# or VB code on View.
• The View Engine is necessary to implement the strongly typed View.

What is the Razor View Engine?

Razor Engine is an advanced view engine that debuted with MVC 3. This is not a new language, but it does use a new markup syntax. Razor features fresh and advanced syntax that is short, expressive, and lower type. Razor syntax is simple to learn and significantly cleaner than Web Form syntax.

Advantages of Razor View Engine

• Easy to Learn: Razor is simple to learn and can be used with existing HTML skills.
• Compact, Expressive, & Fluid: Reduces coding and provides a quick, fluid workflow.
• Smart Parser: Identifies code versus content elements during runtime.
• Markup Integration: Works perfectly with languages such as C# and Visual Basic.
• Layout Pages: Site-wide themes allow for uniform design across multiple pages.
• Tool-independent: Markup can be written in any plain text editor.
• Unit Testing: Views can be tested independently of a controller or web server.
• HTML Helpers: Existing HTML extension methods work flawlessly.
• Clean Code: Encourages readable and maintainable code.
• Built-in Validation: Helps to prevent runtime errors in views.
• Section Concept: Supports optional content placeholders.
• @model Directive: Offers an easy method for defining strongly typed models.

Types of Block Statements in Razor

In Razor, we have several types of block statements available. They are

• A single statement block and an inline expression.
• Multiple Statement Blocks and Inline Expressions.

Web Form View Engine

In the ASP.NET MVC (Model-View-Controller) framework, a "View Engine" renders the user interface (UI) based on the data provided by the controller. A Web Form view engine is explicitly defined as the ASPX view engine, which processes views written in the ASP.NET Web Forms syntax.

Razor View Engine VS Web Form View Engine

• Razor View Engine has a more simple and intuitive syntax for views, whereas Web Form View Engine relies on ASPX markup.
• Razor View Engine enables code-focused development by integrating HTML, whereas Web Form View Engine splits HTML and code behind into different files.
• Razor View Engine allows for easier code maintenance and readability, but Web Form View Engine can result in crowded code due to its inline server tags.
• Razor View Engine simplifies view unit testing, but Web Form View Engine has typically made it more difficult owing to tightly connected code and presentation.
• Razor View Engine performs better while rendering views, however Web Form View Engine may suffer from ViewState overhead and complexity.
• Razor View Engine provides greater freedom in defining layouts and partial views, but Web Form View Engine has tighter control over the page lifecycle and control structure.
• Razor View Engine has been the default view engine since ASP.NET MVC 3, whereas Web Form View Engine was the first choice in previous versions, demonstrating the shift towards more current web development approaches.

Custom View Engine

In ASP.NET MVC, a Custom View Engine allows developers to specify how the MVC framework searches for and renders views. While ASP.NET MVC has built-in view engines such as Razor and Web Forms, developing a custom view engine allows you to enhance or change these processes to meet your application requirements.

When to use a custom view engine?

• When you require customized view locations.
• When improving view rendering performance.
• When utilizing an alternative templating language.
• When creating or updating view search and rendering logic.

Creating a Custom View Engine

ASP.NET MVC is an open-source framework that is very adaptable. You can build your own View engine by implementing the IViewEngine interface or inheriting the VirtualPathProviderViewEngine abstract class.

Registering Custom View Engine in ASP.NET MVC

To use your custom View Engine, register it in the global.asax.cs file's Application_Start() method so that the framework uses it instead of the default one.