Dependency Injection with Unity

This is the most simple and short example of Dependency Injection with Unity.

Create a class with a method in it wich we are going to fire from another class ( the dependent class ), extract a interface from the class and let the inherit from this interface:

Constructor Injection

    public class TestDependency : ITestDependency
    {
        public void TestDependencyMethod()
        {
            System.Windows.Forms.MessageBox.Show("Test dependency method");
        }
    }

Create the independend class, with a property for the dependent class and a constructor wich pass the dependend class, extract a interface from this class and the class inherit from this interface:

    public class TEST : ITEST
    {
        public ITestDependency TestDepency { get; set; }

        public TEST(ITestDependency testdependency)
        {
            TestDepency = testdependency;
        }

        public void TestMethod()
        {
            System.Windows.Forms.MessageBox.Show("Test method");
        }
    }

Now create an instance of a UnityContainer in the root of your application to register the types:

            UnityContainer container = new UnityContainer();
            container.RegisterType(); container.RegisterType(); 

At the place where you need an instance of the dependend class, create the instance by resolve it from the Unity container:

     TEST test = container.Resolve(TEST); 

Try execute both methods to see that unity automatically create an instance of the independ class at the constructor:

            test.TestMethod();
            test.TestDepency.TestDependencyMethod();

Property injection

Property inection is the same as constructor injectioin with the difference that the depencey object is created on a property. If we look at the example above the depend object is passed by the constructor and we are going to change that to a property decorated with the Dependency attribute. Like this:

    public class TEST : ITEST 
    {
        [Dependency]
        public TestDependency TestDepencyProp { get; set; }

        public void TestMethod()
        {
            System.Windows.Forms.MessageBox.Show("Test method");
        }
    }

Call injection

The dependend object is now injection by a method. This method has to be decorated with the InjectionMethod keyword. Example:

        [InjectionMethod]
        public void SetTestDependency(TestDependency testdenpency)
        {
            TestDepencyProp = testdenpency;
        }

Well this is THE most simple example of unity on the internet I think!