C# Dependency Injection with Unity Container: A Practical Guide

Learn how to use the Unity Container for dependency injection in C#. This tutorial explains the principles of dependency injection, demonstrates its implementation using the Unity Container, and highlights how it improves code organization, testability, and maintainability.

Using the Unity Container for Dependency Injection in C#

Dependency Injection (DI) is a design pattern that improves code organization and testability. The Unity Container is a popular DI framework for C# that simplifies dependency management.

Understanding Dependency Injection

Dependency Injection is a technique where dependencies are provided to a class from the outside, rather than the class creating them itself. This reduces coupling between classes, making code more modular, testable, and maintainable.

What is a DI Container?

A DI container is a tool that automates the process of resolving dependencies. It manages object creation and provides dependencies to classes as needed. Key features include:

  • Configuration: Defining which services the container manages.
  • Dependency Resolution: Determining how to create and provide dependencies.
  • Registry: Tracking registered services and dependencies.
  • Lifetime Management: Controlling the lifespan of objects.

The Unity Container

The Unity Container is a lightweight and extensible DI container provided by Microsoft. It simplifies dependency management in C# applications.

Key Features of the Unity Container

  • Ease of Use: Simple API for registering and resolving dependencies.
  • Lightweight: Minimal overhead.
  • Highly Configurable: Allows customization of dependency resolution.
  • Extensible: Can be extended with custom functionality.
  • Multiple Lifetime Managers: Supports different object lifetime strategies.

Benefits of Using the Unity Container

  • Loosely Coupled Code: Reduces dependencies between classes.
  • Improved Testability: Facilitates mocking and unit testing.
  • Scalability: Helps build scalable applications.
  • Faster Development: Streamlines object creation and management.
  • Reduced Code Complexity: Centralizes dependency configuration.

Using the Unity Container

  1. Install the Unity Container: Use NuGet: Install-Package Unity
  2. Create a Container Instance: IUnityContainer container = new UnityContainer();
  3. Register Dependencies: container.RegisterType<ICustomerRepository, CustomerRepository>(); (Registers `CustomerRepository` to be used when `ICustomerRepository` is needed).
  4. Resolve Dependencies: ICustomerRepository repo = container.Resolve<ICustomerRepository>(); (Retrieves an instance).

The Unity container supports constructor, property, and method injection.