Method Injection in Unity Container

Method Injection in Unity Container

Introduction Method Injection is a dependency injection pattern that allows the injection of dependencies into methods. It is commonly used in scenarios where the required dependencies for a method are not known until runtime. In Unity Container, a popular dependency injection framework for .NET, Method Injection can be achieved using various techniques.

1. Constructor Injection Constructor Injection is the most common method injection technique used in Unity Container. Dependencies are injected into a class by passing them as parameters to the constructor. Let's take a look at an example:

csharp
public class MyService
{
    private IMyDependency _dependency;

    public MyService(IMyDependency dependency)
    {
        _dependency = dependency;
    }

    public void MyMethod()
    {
        // Use the injected dependency here
    }
}

In the above example, the MyService class has a dependency on IMyDependency, which is injected through the constructor. Unity Container resolves and injects the appropriate implementation of IMyDependency when creating an instance of MyService.

2. Property Injection Property Injection is another method injection technique where dependencies are injected through public properties of a class. Unity Container can be configured to inject dependencies into properties using attribute-based injection or configuration-based injection. Here's an example using attribute-based injection:

csharp
public class MyService
{
    [Dependency]
    public IMyDependency Dependency { get; set; }

    public void MyMethod()
    {
        // Use the injected dependency here
    }
}

In the above example, the Dependency property is decorated with the [Dependency] attribute, indicating that it should be injected by Unity Container.

3. Method Injection Method Injection, as the name suggests, injects dependencies into methods directly. This technique is useful when dependencies are required for a specific method but not for the entire lifetime of the class. Here's an example:

csharp
public class MyService
{
    public void MyMethod(IMyDependency dependency)
    {
        // Use the injected dependency here
    }
}

In the above example, the MyMethod accepts an IMyDependency parameter, which can be injected by Unity Container when invoking the method.

Conclusion Method Injection in Unity Container provides flexibility in injecting dependencies into methods. By using constructor injection, property injection, or method injection, you can ensure that the required dependencies are available when needed, promoting loose coupling and maintainability in your codebase.