Getting started with unity-container

Remarks#

The Unity Container (Unity) is a lightweight, extensible dependency injection container. It facilitates building loosely coupled applications and provides developers with the following advantages: Simplified object creation, especially for hierarchical object structures and dependencies. [https://msdn.microsoft.com/en-us/library/ff647202.aspx]

It should also mention any large subjects within unity-container, and link out to the related topics. Since the Documentation for unity-container is new, you may need to create initial versions of those related topics.

Versions#

Version	Release Notes	Release date
2.0.0	Unity 2	2011-05-05
2.1.0	Unity 2.1	2011-05-11
3.0.0	Unity 3	2013-04-26
3.5.0	Unity 3.5	2015-05-15
4.0.0	Unity handed over to OSS community	2015-10-06

Installation

In order to get started, you just need to install the Unity nuget package. Run the following command from the package manager console:

PM> Install-Package Unity

Alternatively, you can use Visual Studio to install Unity on a particular project using the Manage NuGet Packages for Solution option under Tools -> NuGet Package Manager.

Hello World

interface IGreeter
{
    void Greet();
}

class Greeter : IGreeter
{
    public void Greet()
    {
        Console.WriteLine("Hello World");
    }
}

class SpanishGreeter : IGreeter
{
    public void Greet()
    {
        Console.WriteLine("Hola Mundo");
    }
}

class FrenchGreeter : IGreeter
{
    public void Greet()
    {
        Console.WriteLine("Bonjour le Monde");
    }
}

class Program
{
    static void Main(string[] args)
    {
        var container = new UnityContainer()
            .RegisterType<IGreeter, SpanishGreeter>("spanish")
            .RegisterType<IGreeter, FrenchGreeter>("french")
            .RegisterType<IGreeter, Greeter>();

        //Get default registration. Outputs "Hello World"
        var greeter = container.Resolve<IGreeter>();
        greeter.Greet();

        //Get specific named registration. Outputs "Hola Mundo"
        greeter = container.Resolve<IGreeter>("spanish");
        greeter.Greet();

        //Get all named registrations (excludes the default one)
        //Outputs "Hola Mundo" and "Bonjour le Monde"
        foreach (var g in container.ResolveAll<IGreeter>())
        {
            g.Greet();
        }

        Console.ReadLine();
    }
}

Constructor Injection

interface IService
{
    void ProcessRequest();
}

interface IRepository
{
    IEnumerable<string> GetData();
}

class HelloWorldRepository : IRepository
{
    public IEnumerable<string> GetData()
    {
        return new[] { "Hello", "World" };
    }
}

class HelloWorldService : IService
{
    private readonly IRepository repo;
    public HelloWorldService(IRepository repo)
    {
        this.repo = repo;
    }
    public void ProcessRequest()
    {
        Console.WriteLine(String.Join(" ", this.repo.GetData()));
    }
}

class Program
{
    static void Main(string[] args)
    {
        var container = new UnityContainer()
            .RegisterType<IRepository, HelloWorldRepository>()
            .RegisterType<IService, HelloWorldService>();

        //Unity automatically resolves constructor parameters that knows about.
        //It will return a HelloWorldService with a HelloWorldRepository
        var greeter = container.Resolve<IService>();
        //Outputs "Hello World"
        greeter.ProcessRequest();            

        Console.ReadLine();
    }
}