Dependency Injector NINJECT full example

Here is example of library, using Ninject and also test

Library:

using Ninject;
using Ninject.Modules;

namespace NinjectExample
{
    #region Interface
    public interface IProduct
    {
        string InsertProduct();
    }
    #endregion

    #region Interface implementation
    public class ConcreteProduct1 : IProduct
    {
        public string InsertProduct()
        {
            string value = "Dependency 1 injection using Ninject";
            return value;
        }
    }

    public class ConcreteProduct2 : IProduct
    {
        public string InsertProduct()
        {
            string value = "Dependency 2 injection using Ninject";
            return value;
        }
    }
    #endregion

    #region Dependency Injector
    internal class ProductsBinder : NinjectModule
    {
        private string _productName;

        public ProductsBinder(string productName)
        {
            _productName = productName;
        }

        public override void Load()
        {
            switch (_productName)
            {
                case "DataAccessLayer1":
                    Bind<IProduct>().To<ConcreteProduct1>();
                    break;
                case "DataAccessLayer2":
                    Bind<IProduct>().To<ConcreteProduct2>();
                    break;
            }
        }
    }
    #endregion

    #region Factory
    public class FactoryProduct
    {
        public static IProduct Create(string name)
        {
            IKernel krn = new StandardKernel(new ProductsBinder(name));
            return krn.Get<IProduct>();
        }
    }
    #endregion
}

Test:

using Microsoft.VisualStudio.TestTools.UnitTesting;
using NinjectExample;

namespace UnitTestProject1
{
    [TestClass]
    public class UnitTest1
    {
        [TestMethod]
        public void TestMethod1()
        {
            IProduct dl = FactoryProduct.Create("DataAccessLayer1");
            Assert.AreEqual("Dependency 1 injection using Ninject", dl.InsertProduct());
        }

        [TestMethod]
        public void TestMethod2()
        {
            IProduct dl = FactoryProduct.Create("DataAccessLayer2");
            Assert.AreEqual("Dependency 2 injection using Ninject", dl.InsertProduct());
        }
    }
}

Of course, all tests passed. 

Dependency Injector NINJECT

Hello

Stuff, i learned recently

For example, there is peace of code:

public partial class MainWindow : Window

{

ISubject _subject;

public MainWindow()

{

_subject = new WeatherData();

}

.... other code....

}

What is a problem with this code?

a couple of.

1. MainWindow should to know about ISubject realization. So, it violate OCP. Class MainWindow do some job and it also instantiate _subject by concrete realization.

2.  If i will want other _subject realization, i will open MainWindow and do changes. It is violates OCP.

3. It is not using Ninject dependency injector ;-)

So, how we fix it?

1. In Visual studio package manager console type :

PM> install-package Ninject

2. Create class, which bind interface and realization by using Ninject:

public class SubjectModule : NinjectModule

{

public override void Load()

{

Bind<ISubject>().To<WeatherData>();

}

}

what is mean, is realization of ISubject is WeatherData

3. Lets create some factory, which use SubjectModule :

public class SubjectFactory

{

public static ISubject Create()

{

IKernel krnl = new StandardKernel(new SubjectModule());

return krnl.Get<ISubject>();

}

}

4. lets do refactoring to MainWindow :

public partial class MainWindow : Window

{

ISubject _subject;

public MainWindow()

{

_subject = SubjectFactory.Create();

}

.... other code....

}

that all!

Now we can change Binding and get other realization inside of MainWindow  without change its code! And, from now, MainWindow  should not know anything about _subject concrete realization

Enjoy

P.S. thanks to Vova about make me to learn it

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