I'm trying to implement dependency injection but i know how to implement the interface and repository of classes then i don't know what shall i do.
This my sample:
public class User
{
public int Id { get; set; }
public string Name { get; set; }
public string LastName { get; set; }
}
This is my interface:
public interface IUser
{
IEnumerable<User> GetUsers();
void AddUser(User user);
void EditUser(User user);
void DeleteUser(int id);
User UserGetById(int id);
void Save();
}
This is my repository:
public class UserRepsitory:IUser
{
private _Context _context;
public UserRepsitory(_Context _context)
{
this._context = _context;
}
public IEnumerable<User> GetUsers()
{
return _context.User.ToList();
}
public void AddUser(User user)
{
_context.User.Add(user);
}
public void EditUser(User user)
{
_context.Entry(user).State = System.Data.Entity.EntityState.Modified;
}
public User UserGetById(int id)
{
return _context.User.Find(id);
}
public void Save()
{
_context.SaveChanges();
}
public void DeleteUser(int id)
{
var Search = _context.User.Find(id);
_context.User.Remove(Search);
}
}
And one of method in controller:
private IUser userRepsitory;
public UsersController()
{
this.userRepsitory = new UserRepsitory(new _Context());
}
public UsersController(IUser UserRepository)
{
this.userRepsitory = UserRepository;
}
public ActionResult Index()
{
return View(userRepsitory.GetUsers());
}
What is the next step?
The first thing is, get rid of the default constructor where we are hard coding the initialization of UserRepository ! We will do that in the dependency injection way.
public UsersController : Controller
{
private readonly IUser userRepsitory;
public UsersController(IUser UserRepository)
{
this.userRepsitory = UserRepository;
}
public ActionResult Index()
{
return View(userRepsitory.GetUsers());
}
}
Now we need something to tell the MVC framework which version/implementation of IUser should be used when the code runs. you can use any dependency injection frameworks to do that. For example, If you are in MVC 6, you can use the inbuilt dependency injection framework to do that. So go to your Startup class and in your ConfigureServices method, you can map an interface to a concrete implementation.
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
services.AddTransient<IUser, UserRepository>();
}
}
If you are in a previous version of MVC, you may consider using any of the dependency injection frameworks available like Unity, Ninject etc.
It is pretty much same, you map an interface to a concrete implementation
Ninject
private static void RegisterServices(IKernel kernel)
{
kernel.Bind<IUser>().To<UserRepository>();
}
You do not need to put the mapping in a cs file. You can define that in a config file. For example, when you use Unity you can do something like this in your config file (web config or an external config file for unity configuration)
Unity
<alias alias="IUser" type="YourNamespace.IUser, YourAssemblyName" />
<register type="IUser" mapTo="YourNamespace.UseRepository, YourAssemblyName">
In order to create and configure your project with Spring DI(Dependency Feature) you must configure beans.
Create an xml file (if its not there) and add references to bean
In this xml file, provide references to the classes you want to inject. Example:
<bean id="Name of the JAVA Class" class="the Full path of the JAVA class"/>
And in your class where you are supposed to call the referencing class(above), calling procedure would be like :
#Controller
public class MyController {
private full.path.of.my.class.named.MyJavaClass _class;
#Autowired
private MyController (full.path.of.my.class.MyJavaClass class)
{
this._class= class;
}
}
Now say if you a function in MyJavaClass
public int sum(int x, int y){
return x+y;
}
Then without creating object of MyJavaClass you can inject like the following in your controller:
_class.Sum(10,15);
YOU DO NOT CREATE AN INSTANCE OF THIS CLASS.
My DbContext implementation implements two interfaces.
I'm trying to follow best practices and instantiate one DbContext instance per HTTP request.
However, I have a controller action where I need to instantiate two classes, each of which takes different interface in constructor.
I am worried if in that scenario, for that specific action, two DbContext instances would be raised.
I've setup my ContainerBuilder like this:
builder.RegisterType<MyDbContext>()
.As<IWorkflowPersistenceStore>()
.As<IDocumentPersistenceStore>()
.InstancePerHttpRequest();
builder.RegisterType<WorkflowManager>().As<IWorkflowManager>().InstancePerHttpRequest();
builder.RegisterType<DocumentManager>().As<IDocumentManager>().InstancePerHttpRequest();
public class OperationController : Controller
{
private IWorkflowManager _workflowManager;
private IDocumentManager _documentManager;
public OperationController(IWorkflowManager workflowManager, IDocumentManager documentManager)
{
_workflowManager = workflowManager;
_documentManager = documentManager;
}
public ActionResult SaveWorkflowDocument(...)
{
// will my managers point to same DbContext?
_workflowManager.DoSomething(...);
_documentManager.DoSomethingElse(...);
return View();
}
}
public class WorkflowManager : IWorkflowManager
{
private IWorkflowPersistenceStore _store;
public WorkflowManager(IWorkflowPersistenceStore store)
{
_store = store;
}
}
public class DocumentManager : IDocumentManager
{
private IDocumentPersistenceStore _store;
public DocumentManager (IDocumentPersistenceStore store)
{
_store = store;
}
}
Is this good enough?
Do I have to add .SingleInstance()? I'm worried that it might create singleton for whole application.
I think you're ok with what you have. Test passes:
using Autofac;
using NUnit.Framework;
namespace AutofacTest
{
[TestFixture]
public class ScopeTest
{
[Test]
public void Test()
{
var builder = new ContainerBuilder();
builder.RegisterType<Component>()
.As<IServiceA>()
.As<IServiceB>()
.InstancePerLifetimeScope();
using (var container = builder.Build())
using (var scope = container.BeginLifetimeScope())
{
var a = scope.Resolve<IServiceA>();
var b = scope.Resolve<IServiceB>();
Assert.AreEqual(a, b);
}
}
}
public interface IServiceA { }
public interface IServiceB { }
public class Component : IServiceA, IServiceB { }
}
I'm using AutoMapper in an ASP.NET MVC application. I was told that I should move the AutoMapper.CreateMap elsewhere as they have a lot of overhead. I'm not too sure how to design my application to put these calls in just 1 place.
I have a web layer, service layer and a data layer. Each a project of its own. I use Ninject to DI everything. I'll utilize AutoMapper in both web and service layers.
So what are your setup for AutoMapper's CreateMap? Where do you put it? How do you call it?
Doesn't matter, as long as it's a static class. It's all about convention.
Our convention is that each "layer" (web, services, data) has a single file called AutoMapperXConfiguration.cs, with a single method called Configure(), where X is the layer.
The Configure() method then calls private methods for each area.
Here's an example of our web tier config:
public static class AutoMapperWebConfiguration
{
public static void Configure()
{
ConfigureUserMapping();
ConfigurePostMapping();
}
private static void ConfigureUserMapping()
{
Mapper.CreateMap<User,UserViewModel>();
}
// ... etc
}
We create a method for each "aggregate" (User, Post), so things are separated nicely.
Then your Global.asax:
AutoMapperWebConfiguration.Configure();
AutoMapperServicesConfiguration.Configure();
AutoMapperDomainConfiguration.Configure();
// etc
It's kind of like an "interface of words" - can't enforce it, but you expect it, so you can code (and refactor) if necessary.
EDIT:
Just thought I'd mention that I now use AutoMapper profiles, so the above example becomes:
public static class AutoMapperWebConfiguration
{
public static void Configure()
{
Mapper.Initialize(cfg =>
{
cfg.AddProfile(new UserProfile());
cfg.AddProfile(new PostProfile());
});
}
}
public class UserProfile : Profile
{
protected override void Configure()
{
Mapper.CreateMap<User,UserViewModel>();
}
}
Much cleaner/more robust.
You can really put it anywhere as long as your web project references the assembly that it is in. In your situation I would put it in the service layer as that will be accessible by the web layer and the service layer and later if you decide to do a console app or you are doing a unit test project the mapping configuration will be available from those projects as well.
In your Global.asax you will then call the method that sets all of your maps. See below:
File AutoMapperBootStrapper.cs
public static class AutoMapperBootStrapper
{
public static void BootStrap()
{
AutoMapper.CreateMap<Object1, Object2>();
// So on...
}
}
Global.asax on application start
just call
AutoMapperBootStrapper.BootStrap();
Now some people will argue against this method violates some SOLID principles, which they have valid arguments. Here they are for the reading.
Configuring Automapper in Bootstrapper violates Open-Closed Principle?
Update: The approach posted here is no more valid as SelfProfiler has been removed as of AutoMapper v2.
I would take a similar approach as Thoai. But I would use the built-in SelfProfiler<> class to handle the maps, then use the Mapper.SelfConfigure function to initialize.
Using this object as the source:
public class User
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public DateTime BirthDate { get; set; }
public string GetFullName()
{
return string.Format("{0} {1}", FirstName, LastName);
}
}
And these as the destination:
public class UserViewModel
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
}
public class UserWithAgeViewModel
{
public int Id { get; set; }
public string FullName { get; set; }
public int Age { get; set; }
}
You can create these profiles:
public class UserViewModelProfile : SelfProfiler<User,UserViewModel>
{
protected override void DescribeConfiguration(IMappingExpression<User, UserViewModel> map)
{
//This maps by convention, so no configuration needed
}
}
public class UserWithAgeViewModelProfile : SelfProfiler<User, UserWithAgeViewModel>
{
protected override void DescribeConfiguration(IMappingExpression<User, UserWithAgeViewModel> map)
{
//This map needs a little configuration
map.ForMember(d => d.Age, o => o.MapFrom(s => DateTime.Now.Year - s.BirthDate.Year));
}
}
To initialize in your application, create this class
public class AutoMapperConfiguration
{
public static void Initialize()
{
Mapper.Initialize(x=>
{
x.SelfConfigure(typeof (UserViewModel).Assembly);
// add assemblies as necessary
});
}
}
Add this line to your global.asax.cs file: AutoMapperConfiguration.Initialize()
Now you can place your mapping classes where they make sense to you and not worry about one monolithic mapping class.
For those of you who adhere to the following:
using an ioc container
don't like to break open closed for this
don't like a monolithic config file
I did a combo between profiles and leveraging my ioc container:
IoC configuration:
public class Automapper : IWindsorInstaller
{
public void Install(IWindsorContainer container, IConfigurationStore store)
{
container.Register(Classes.FromThisAssembly().BasedOn<Profile>().WithServiceBase());
container.Register(Component.For<IMappingEngine>().UsingFactoryMethod(k =>
{
Profile[] profiles = k.ResolveAll<Profile>();
Mapper.Initialize(cfg =>
{
foreach (var profile in profiles)
{
cfg.AddProfile(profile);
}
});
profiles.ForEach(k.ReleaseComponent);
return Mapper.Engine;
}));
}
}
Configuration example:
public class TagStatusViewModelMappings : Profile
{
protected override void Configure()
{
Mapper.CreateMap<Service.Contracts.TagStatusViewModel, TagStatusViewModel>();
}
}
Usage example:
public class TagStatusController : ApiController
{
private readonly IFooService _service;
private readonly IMappingEngine _mapper;
public TagStatusController(IFooService service, IMappingEngine mapper)
{
_service = service;
_mapper = mapper;
}
[Route("")]
public HttpResponseMessage Get()
{
var response = _service.GetTagStatus();
return Request.CreateResponse(HttpStatusCode.Accepted, _mapper.Map<List<ViewModels.TagStatusViewModel>>(response));
}
}
The trade-off is that you have to reference the Mapper by the IMappingEngine interface instead of the static Mapper, but that's a convention I can live with.
All of above solutions provide a static method to call (from app_start or any where) that it should call other methods to configure parts of mapping-configuration. But, if you have a modular application, that modules may plug in and out of application at any time, these solutions does not work. I suggest using WebActivator library that can register some methods to run on app_pre_start and app_post_start any where:
// in MyModule1.dll
public class InitMapInModule1 {
static void Init() {
Mapper.CreateMap<User, UserViewModel>();
// other stuffs
}
}
[assembly: PreApplicationStartMethod(typeof(InitMapInModule1), "Init")]
// in MyModule2.dll
public class InitMapInModule2 {
static void Init() {
Mapper.CreateMap<Blog, BlogViewModel>();
// other stuffs
}
}
[assembly: PreApplicationStartMethod(typeof(InitMapInModule2), "Init")]
// in MyModule3.dll
public class InitMapInModule3 {
static void Init() {
Mapper.CreateMap<Comment, CommentViewModel>();
// other stuffs
}
}
[assembly: PreApplicationStartMethod(typeof(InitMapInModule2), "Init")]
// and in other libraries...
You can install WebActivator via NuGet.
In addition to the best answer, a good way is using Autofac IoC liberary to add some automation. With this you just define your profiles regardless of initiations.
public static class MapperConfig
{
internal static void Configure()
{
var myAssembly = Assembly.GetExecutingAssembly();
var builder = new ContainerBuilder();
builder.RegisterAssemblyTypes(myAssembly)
.Where(t => t.IsSubclassOf(typeof(Profile))).As<Profile>();
var container = builder.Build();
using (var scope = container.BeginLifetimeScope())
{
var profiles = container.Resolve<IEnumerable<Profile>>();
foreach (var profile in profiles)
{
Mapper.Initialize(cfg =>
{
cfg.AddProfile(profile);
});
}
}
}
}
and calling this line in Application_Start method:
MapperConfig.Configure();
The above code finds all Profile sub classes and initiate them automatically.
Putting all the mapping logic in 1 location is not a good practice for me. Because the mapping class will be extremely large and very hard to maintain.
I recommend put the mapping stuff together with the ViewModel class in the same cs file. You can easily navigate to the mapping definition you want following this convention. Moreover, while creating the mapping class, you can reference to the ViewModel properties faster since they are in the same file.
So your view model class will look like:
public class UserViewModel
{
public ObjectId Id { get; set; }
public string Firstname { get; set; }
public string Lastname { get; set; }
public string Email { get; set; }
public string Password { get; set; }
}
public class UserViewModelMapping : IBootStrapper // Whatever
{
public void Start()
{
Mapper.CreateMap<User, UserViewModel>();
}
}
From new version of AutoMapper using static method Mapper.Map() is deprecated. So you can add MapperConfiguration as static property to MvcApplication (Global.asax.cs) and use it to create instance of Mapper.
App_Start
public class MapperConfig
{
public static MapperConfiguration MapperConfiguration()
{
return new MapperConfiguration(_ =>
{
_.AddProfile(new FileProfile());
_.AddProfile(new ChartProfile());
});
}
}
Global.asax.cs
public class MvcApplication : System.Web.HttpApplication
{
internal static MapperConfiguration MapperConfiguration { get; private set; }
protected void Application_Start()
{
MapperConfiguration = MapperConfig.MapperConfiguration();
...
}
}
BaseController.cs
public class BaseController : Controller
{
//
// GET: /Base/
private IMapper _mapper = null;
protected IMapper Mapper
{
get
{
if (_mapper == null) _mapper = MvcApplication.MapperConfiguration.CreateMapper();
return _mapper;
}
}
}
https://github.com/AutoMapper/AutoMapper/wiki/Migrating-from-static-API
For those who are (lost) using:
WebAPI 2
SimpleInjector 3.1
AutoMapper 4.2.1 (With Profiles)
Here's how I managed integrating AutoMapper in the "new way". Also,
a Huge thanks to this answer(and question)
1 - Created a folder in the WebAPI project called "ProfileMappers". In this folder I place all my profiles classes which creates my mappings:
public class EntityToViewModelProfile : Profile
{
protected override void Configure()
{
CreateMap<User, UserViewModel>();
}
public override string ProfileName
{
get
{
return this.GetType().Name;
}
}
}
2 - In my App_Start, I have a SimpleInjectorApiInitializer which configures my SimpleInjector container:
public static Container Initialize(HttpConfiguration httpConfig)
{
var container = new Container();
container.Options.DefaultScopedLifestyle = new WebApiRequestLifestyle();
//Register Installers
Register(container);
container.RegisterWebApiControllers(GlobalConfiguration.Configuration);
//Verify container
container.Verify();
//Set SimpleInjector as the Dependency Resolver for the API
GlobalConfiguration.Configuration.DependencyResolver =
new SimpleInjectorWebApiDependencyResolver(container);
httpConfig.DependencyResolver = new SimpleInjectorWebApiDependencyResolver(container);
return container;
}
private static void Register(Container container)
{
container.Register<ISingleton, Singleton>(Lifestyle.Singleton);
//Get all my Profiles from the assembly (in my case was the webapi)
var profiles = from t in typeof(SimpleInjectorApiInitializer).Assembly.GetTypes()
where typeof(Profile).IsAssignableFrom(t)
select (Profile)Activator.CreateInstance(t);
//add all profiles found to the MapperConfiguration
var config = new MapperConfiguration(cfg =>
{
foreach (var profile in profiles)
{
cfg.AddProfile(profile);
}
});
//Register IMapper instance in the container.
container.Register<IMapper>(() => config.CreateMapper(container.GetInstance));
//If you need the config for LinqProjections, inject also the config
//container.RegisterSingleton<MapperConfiguration>(config);
}
3 - Startup.cs
//Just call the Initialize method on the SimpleInjector class above
var container = SimpleInjectorApiInitializer.Initialize(configuration);
4 - Then, in your controller just inject as usually a IMapper interface:
private readonly IMapper mapper;
public AccountController( IMapper mapper)
{
this.mapper = mapper;
}
//Using..
var userEntity = mapper.Map<UserViewModel, User>(entity);
For vb.net programmers using the new Version (5.x) of AutoMapper.
Global.asax.vb:
Public Class MvcApplication
Inherits System.Web.HttpApplication
Protected Sub Application_Start()
AutoMapperConfiguration.Configure()
End Sub
End Class
AutoMapperConfiguration:
Imports AutoMapper
Module AutoMapperConfiguration
Public MapperConfiguration As IMapper
Public Sub Configure()
Dim config = New MapperConfiguration(
Sub(cfg)
cfg.AddProfile(New UserProfile())
cfg.AddProfile(New PostProfile())
End Sub)
MapperConfiguration = config.CreateMapper()
End Sub
End Module
Profiles:
Public Class UserProfile
Inherits AutoMapper.Profile
Protected Overrides Sub Configure()
Me.CreateMap(Of User, UserViewModel)()
End Sub
End Class
Mapping:
Dim ViewUser = MapperConfiguration.Map(Of UserViewModel)(User)
I have successfully setup a simple mvc application that lists teams. I'm using Ninject to inject the appropriate repository depending on the controller (thanks to stack overflow ;). All looks good, except that the repository code looks exactly the same. And I know that's wrong. So my TeamRepository has two classes (for now).
public class SwimTeamRepository : ITeamRepository<SwimTeam>
{
private readonly Table<SwimTeam> _teamTable;
public SwimTeamRepository(string connectionString)
{
_teamTable = (new DataContext(connectionString).GetTable<SwimTeam>());
}
public IQueryable<SwimTeam> Team
{
get { return _teamTable; }
}
}
public class SoccerTeamRepository : ITeamRepository<SoccerTeam>
{
private readonly Table<SoccerTeam> _teamTable;
public SoccerTeamRepository(string connectionString)
{
_teamTable = (new DataContext(connectionString).GetTable<SoccerTeam>());
}
public IQueryable<SoccerTeam> Team
{
get { return _teamTable; }
}
}
They look exactly the same except for the Class and Table name, so clearly I need to re-factor this. What would be the best approach here? Singleton? Factory Method?
Thanks in advance!
You could use generics:
public interface ITeamRepository<T>
{
}
public class TeamRepository<TTeam> : ITeamRepository<TTeam>
where TTeam : Team
{
private readonly Table<TTeam> _teamTable;
public TeamRepository(string connectionString)
{
_teamTable = (new DataContext(connectionString).GetTable<TTeam>());
}
public IQueryable<TTeam> Team
{
get { return _teamTable; }
}
}
public class Team
{
}
public class SwimTeam : Team
{
}
Then use it like so...
public void MyMethod()
{
var repository = new TeamRepository<SwimTeam>();
}
...and set up your IoC container w/ Ninject like so...
public class MyModule : NinjectModule
{
public override void Load()
{
Bind<ITeamRepository<SwimTeam>>
.To<TeamRepository<SwimTeam>>();
}
}
public void MyMethod()
{
var repository = kernel.Get<ITeamRepository<SwimTeam>>();
}
If you want to get REAL generic and have a single repository for ALL of your mapped classes, you can do something like this:
public interface IRepository
{
IQueryable<T> Get<T>() where T : class, new();
}
public class Repository : IRepository, IDisposable
{
private DataContext _dataContext;
public Repository(string connectionString)
{
_dataContext = new DataContext(connectionString);
}
public IQueryable<T> Get<T>()
where T : class, new()
{
return _dataContext.GetTable<T>().AsQueryable();
}
public void Dispose()
{
if (_dataContext != null)
{
_dataContext.Dispose();
_dataContext = null;
}
}
}
...which you could call like so (after setting up your Ninject container)...
using (var repository = kernel.Get<IRepository>())
{
var swimTeam = repository.Get<SwimTeam>();
}
Since Ninject takes care of the life-cycle management of your objects, you don't HAVE to wrap the repository in a using statement. In fact, you don't want to use a using statement there at all if you plan to use the repository more than once within the scope of its lifetime. Ninject will automatically dispose of it when it's life-cycle ends.
Here's a good article by Rob Conery on using this kind of technique to reduce the friction of using different ORMs.
EDIT by keeg:
I Think
public class TeamRepository<TTeam> : ITeamRepository<TTeam> where TTeam : Team {}
Should be
public class TeamRepository<TTeam> : ITeamRepository<TTeam> where TTeam : class {}
Please correct if I'm wrong.
Is this what you want?
public class TeamRepository : ITeamRepository<T>
{
private readonly Table<T> _teamTable;
public TeamRepository(string connectionString)
{
_teamTable = (new DataContext(connectionString).GetTable<T>());
}
public IQueryable<T> Team
{
get { return _teamTable; }
}
}
I'm trying to work with NInject in my MVC 3 application, and i have one question.
Interface
public interface ITalesRepository
{
IEnumerable<Tale> GetAllTales();
}
Repository
public class TalesRepository : ITalesRepository
{
private FairyTalesMVC3DataContext _dataContext;
public TalesRepository(FairyTalesMVC3DataContext dataContext)
{
_dataContext = dataContext;
}
public IEnumerable<Tale> GetAllTales()
{
return _dataContext.Tales.OrderBy(c => c.NameAn);
}
}
Home controller
public class HomeController : Controller
{
private readonly ITalesRepository _talesRepository;
public HomeController(ITalesRepository talesRepository)
{
_talesRepository = talesRepository;
}
public ActionResult Index()
{
ViewBag.Tales = _talesRepository.GetAllTales();
return View();
}
}
So, i need to initialize my TalesRepository with DataContext, and now it is so:
private void RegisterDependencyResolver()
{
var kernel = new StandardKernel();
kernel.Bind<ITalesRepository>().To<TalesRepository>().WithConstructorArgument("dataContext", new FairyTalesMVC3DataContext(ConfigurationManager.ConnectionStrings["dbFairyTalesConnectionString"].ConnectionString));
DependencyResolver.SetResolver(new NinjectDependencyResolver(kernel));
}
So, my question, is it ok or something wrong?
First of all:
public IEnumerable<Tale> GetAllTales()
{
return _dataContext.Tales.OrderBy(c => c.NameAn);
}
I would add .ToList() to the end. Else you'll get data layer exceptions in your presentation layer which is not fine.
Next, I would recommend that you switch to ViewModels instead of using ViewBag. It's a lot easier to prevent that logic leaks into the views if you are using ViewModels. Since you can add the logic to the ViewModel and thus get the same behaviour in all views using the model.
Your application should inherit from NinjectHttpApplication. It registers dependency resolver, so you don't have to do it.
You should also override CreateKernel in application class and register your own module with bindings:
public class MvcApplication : NinjectHttpApplication
{
protected override IKernel CreateKernel()
{
return new StandardKernel(new INinjectModule[] {new MvcModule()});
}
}
public class MvcModule : NinjectModule
{
public override void Load()
{
Bind<ITalesRepository>().To<TalesRepository>();
Bind<FairyTalesMVC3DataContext>().To<FairyTalesMVC3DataContext>().InRequestScope();
}
}