Dependency Injection with Simple Injector

In this post we are going to use same example that I have used for StructureMap post. So let’s create a console application for this.



Now it’s time to add Simple Injector to the project. You can use it via following nuget package.

Install-Package SimpleInjector

After adding nuget package it’s time to write some code. I am going to create a shopping cart to represent some of scenarios.

namespace SimpleInjectorDemo
{
    public interface IOrder
    {
        void Process();
    }
}

Here I have creaed IOrder interace which will be implemented by PurchaseOrder class.

using System;

namespace SimpleInjectorDemo
{
    public class PurchaseOrder : IOrder
    {
        public void Process()
        {
            Console.WriteLine("Purchase Order processed");
        }
    }
}

Now it’s time to write our shopping cart code. Following is a code for that.

namespace SimpleInjectorDemo
{
    public class ShoppingCart
    {
        private readonly IOrder _order;

        public ShoppingCart(IOrder order)
        {
            _order = order;
        }

        public void CheckOut()
        {
            _order.Process();
        }
    }
}

If you see whole source code carefully you can see that ShoppingCart class requires a IOrder object to construct object of ShoppingCart class. We are going to inject this value with the help of Simple Injector dependency injection library.

namespace SimpleInjectorDemo
{
    class Program
    {
        static void Main(string[] args)
        {
            var container = new SimpleInjector.Container();
            container.Register<IOrder,PurchaseOrder>();

            var shoppingCart = container.GetInstance<ShoppingCart>();
            shoppingCart.CheckOut();
        }
    }
}

Here you can see that I have created a container and use register method to configure a container. I have mapped IOrder to PurchaseOrder so that whenever any Instance of IOrder require it will create a object of PurchaseOrder class. Then I will call method to get a instance of Shopping cart and call a method to checkout.

Now let’s run application and following is a output as expected.


That’s it. Hope you like it. Stay tuned fore more!!

You can find complete source code of above blog post at following location on github. https://github.com/dotnetjalps/SimpleInjectorSimpleExample