Chapter 13Dependency Injection

—by Brad Wilson

What's In This Chapter?

  • Understanding software design patterns
  • Using the dependency resolver in MVC
  • Using the dependency resolver in Web API

As of version 3, ASP.NET MVC has included a dependency resolver that dramatically improves the ability of an application to participate in dependency injection for both services consumed by MVC and commonly created classes like controllers and view pages.

To understand how the dependency resolver works, we first need to define some of the common software patterns that it uses. If you're already familiar with patterns such as service location and dependency injection, you might want to skim or skip the next section and go directly to the “Dependency Resolution in MVC” section.


To understand what dependency injection is and how you can apply it to MVC applications, you need to understand software design patterns. A software design pattern is used to formalize the description of a problem and a solution to that problem, so that developers can use the pattern to simplify the identification and communication of common problems and solutions.

The design pattern isn't necessarily to claim the invention of something new or novel, but rather exists to give a formal name and definition from common practices in the industry. When you read about a design pattern, you might recognize it from solutions you've used in particular problems in the past.

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