How to inject my dbContext with Unity

Question

How do I inject my dbContext class using Unity? I can\'t just create a Interface like for my other \"normal\" classes? What should I do with my RequestContext class and what

Answer 1

This site has a GREAT tutorial on how to get Unity working: https://medium.com/aeturnuminc/repository-pattern-with-dependency-injection-mvc-ef-code-first-91344413ba1c

I'm going to assume you have Entity Framework installed, know how to create a viewmodel and put on attributes using System.ComponentModel.DataAnnotations and System.ComponentModel.DataAnnotations.Schema namespaces, and I'll assume you can create a view and controller. None of that is really relevant until the end, anyway.

You have to get the NuGet package Unity to install these references:

• Microsoft.Practices.Unity
• Unity.Mvc3 (or 4 or 5)

My DataContext (Model1.cs) looks like this:

public partial class Model1 : DbContext
{
    public Model1()
        : this(true)
    { }

    public Model1(bool enableLazyLoading = true)
        : base("name=Model1")
    {
        // You can do this....
        //Database.SetInitializer(new CreateDatabaseIfNotExists());            
        //this.Configuration.LazyLoadingEnabled = false;

        // or this...
        Database.SetInitializer(null);
        this.Configuration.ProxyCreationEnabled = false;

        ((IObjectContextAdapter)this).ObjectContext.ContextOptions.ProxyCreationEnabled = enableLazyLoading;
        ((IObjectContextAdapter)this).ObjectContext.ContextOptions.LazyLoadingEnabled = enableLazyLoading;
    }

    // All my tables and views are assigned to models, here...

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Conventions.Remove();
        base.OnModelCreating(modelBuilder);
    }
}

My Repository (DataRepository.cs) looks like this:

namespace WeeklyReport.Repository
{
    public class DataRepository : IDataRepository
    {
        private bool disposing;
        private readonly Model1 context;

        public virtual void Dispose()
        {
            if (disposing)
            {
                return;
            }

            disposing = true;

            if (context != null)
            {
                context.Dispose();
            }
        }

        public void SaveChanges()
        {
            context.SaveChanges();
        }

        public DataRepository()
        {
            context = new Model1();
            context.Configuration.ProxyCreationEnabled = false;
        }

        public IEnumerable GetAllMetrics()
        {
            var myMetrics = context.MetricsTable; // put into ReportVM and return, etc.
        }
        // etc., etc.
    }
}

My Interface (IDataRepository.cs) looks like this:

namespace WeeklyReport.Repository
{
    public interface IDataRepository
    {
        void SaveChanges();
        IEnumerable GetAllMetrics();
    }
}

My UnityConfig.cs in the App_Start folder looks like this:

using Microsoft.Practices.Unity;
using WeeklyReport.Repository;
using System.Web.Mvc;
using Unity.Mvc3;

namespace WeeklyReport
{
    public class UnityConfig
    {
        public static void RegisterContainer()
        {
            var container = new UnityContainer();

            //ensure the repository is disposed after each request by using the lifetime manager
            container.RegisterType(new HierarchicalLifetimeManager());

            DependencyResolver.SetResolver(new UnityDependencyResolver(container));

        } 
    }
}

And you have to call RegisterContainer in Global.ascx.cs inside Application_Start:

UnityConfig.RegisterContainer();

From a controller, it gets a handle to IDataRepository:

using WeeklyReport.Repository;

namespace WeeklyReport.Controllers
{    
    public class ReportController : Controller
    {
        private readonly IDataRepository repository;
        public ReportController(IDataRepository repository)
        {
            this.repository = repository;
        }

        public ActionResult Index()
        {
            List reportVM = new List();
            var reqs = repository.GetAllMetrics();
            // iterate reqs and put into reportVM, etc.
            return View(reportVM);
        }
    }
}

And you can call repository as if it was the real class - you're just getting an interface instance to it.