We Keep Coding

MOQ SetupGet dbContext with constructor parameters

Situation
Here I am, trying to write some unit tests for my GroupService with the use of MOQ.
To create an instance of my GroupService, I mocked 4 interfaces that needed to be passed through the constructor. Now on one of the mocks (IGroupRepository) a property called Context is called and my idea was to SetupGet this property and just simply return a fake list of GroupUser. But I keep getting errors, whatever I try.
Code
public class GroupServiceTests
{
private readonly GroupService _groupService;
private readonly Mock<AppDbContext> _dbContext;
private readonly Mock<IGroupRepository> _groupRepository;
private readonly Mock<IComponentService> _componentService;
private readonly Mock<IUserContextService> _userContextService;
private readonly Mock<IModelEntityMapper<Group, Core.DbContexts.Entities.Group>> _mapper;
public GroupServiceTests()
{
var groupUsersMock = CreateDbSetMock(GetFakeListOfGroupUsers());
_dbContext = new Mock<AppDbContext>(new DbContextOptions<AppDbContext>());
_dbContext.SetupGet(x => x.GroupUser).Returns(groupUsersMock.Object);
_groupRepository = new Mock<IGroupRepository>();
_groupRepository.SetupGet(repo => repo.Context).Returns(_dbContext.Object);
_componentService = new Mock<IComponentService>();
_userContextService = new Mock<IUserContextService>();
_mapper = new Mock<IModelEntityMapper<Group, Core.DbContexts.Entities.Group>>();
_groupService = new GroupService(_groupRepository.Object, _componentService.Object, _userContextService.Object, _mapper.Object);
}
}
In the GroupService this line is called:
// _repository reffers to IGroupRepository
userIdsForContextReset.AddRange(_repository.Context.GroupUser.Where(x => groupIds.Contains(x.GroupId)).Select(x => x.UserId));
And the GroupRepository and EntityRepository look like this:
public interface IGroupRepository : IEntityRepository<AppDbContext, Group>
{
List<GroupPermission> GetInheritedGroupPermissions(int groupId);
}
public class GroupRepository : EntityRepository<AppDbContext, Group>, IGroupRepository
{
public GroupRepository(AppDbContext dbContext) : base(dbContext)
{
}
public List<GroupPermission> GetInheritedGroupPermissions(int groupId)
{
// Removed for brevity
}
}
public class EntityRepository<TDbContext, TEntity> : EntityRepository<TDbContext, TEntity, int>, IEntityRepository<TDbContext, TEntity>
where TDbContext : DbContext
where TEntity : class, IEntity<int>
{
public EntityRepository(TDbContext dbContext) : base(dbContext)
{
}
}
public class EntityRepository<TDbContext, TEntity, TId> : IEntityRepository<TDbContext, TEntity, TId>
where TDbContext : DbContext
where TEntity : class, IEntity<TId>
where TId : IComparable
{
public EntityRepository(TDbContext context)
{
Context = context;
}
public TDbContext Context { get; }
}
And last but not least, the AppDbContext and SqlDbContext:
public class AppDbContext : Shared.DbContexts.SqlDbContext
{
public virtual DbSet<GroupUser> GroupUser { get; set; }
public AppDbContext(DbContextOptions<AppDbContext> options) : base(options)
{
}
}
public class SqlDbContext : DbContext
{
public SqlDbContext(DbContextOptions options) : base(options)
{
ChangeTracker.QueryTrackingBehavior = QueryTrackingBehavior.NoTracking;
ChangeTracker.StateChanged += ChangeTracker_StateChanged;
}
}
Error
The error that I am getting is inside the SqlDbContext on the 1st line inside the constructor and says the following:
System.InvalidOperationException: 'No database provider has been configured for this DbContext. A provider can be configured by overriding the DbContext.OnConfiguring method or by using AddDbContext on the application service provider. If AddDbContext is used, then also ensure that your DbContext type accepts a DbContextOptions object in its constructor and passes it to the base constructor for DbContext.'
What am I doing wrong?

When you mock an implementation it creates the object using the constructor matching the parameters provided; it runs that code.
Additionally, anything not able to be mocked (not virtual or abstract) will run as is. In this case, you're passing in DbContextOptions and you haven't specified a provider, and something needs that.
This can be an opinionated topic, however to solve your problem there are a number of ways you could do it:
Add a parameterless constructor to your DbContext for testing. I wouldn't recommend this as I follow the mantra of not changing your SUT for a test.
Use an in-memory provider; EF Core In-Memory Database Provider or SQLite EF Core Database Provider are two that I have used. They do have limitations but for the OP usage would probably be fine and addresses Microsofts notes about how you shouldn't mock the DbContext.
Use an existing library such as EntityFrameworkCore.Testing (disclaimer, I am the author) which will extend in-memory providers to address their limitations.

Abstract Entity Framework

I want to create an abstraction layer between Entity Framework and the rest of my application. But I am having a few problems with Entity Framework.
Basically (I don't show you all the interface layers that I've created too), I've split my application into several projects like this :
Domain
Contains my domain object, an abstraction of my datastorage object
DAL
Creates a link between my datastorage and my business layer. Contains two types of elements :
Private ones : my EDMX, my database object, and some other generated objects providing me some useful methods like ToDomain/ToEntity
Public ones : my Data Access Object, providing CRUD methods
Business
Contains the logic of my application. Only knows about the public elements of the DAL and the Domain Layer.
Presentation
Presents the domain objects for the user. Only knows about the business layer.
As I said, I want to create an abstraction of my datastorage objects (in my case Database object, but I want a solution that works also for file or WCF storage for example) so that my business layer don't know anything about my DAL implementation.
Here is a glimpse of what I've done in my DAL :
public abstract class GenericDao<TEntity, TDomain, TDbContext> : IGenericDao<TDomain>
where TDbContext : DbContext, new()
where TEntity : class
where TDomain : class
{
protected TDbContext _context;
protected DbSet<TEntity> _dbSet;
public GenericDao(TDbContext dbContext)
{
this._context = dbContext;
this._dbSet = dbContext.Set<TEntity>();
}
public TDomain Create()
{
return this.ToDomain(this._dbSet.Create());
}
public IList<TDomain> GetAll()
{
return this._dbSet.ToList().Select(entity => this.ToDomain(entity)).ToList();
}
public void Update(TDomain domain)
{
var entity = this.ToEntity(domain);
var entry = this._context.Entry(entity);
entry.State = EntityState.Modified;
}
public void Remove(TDomain domain)
{
_dbSet.Remove(this.ToEntity(domain));
}
protected abstract TDomain ToDomain(TEntity entity);
protected abstract TEntity ToEntity(TDomain domain);
}
You will probably see what's wrong with my code by reading it: when I try to delete or update an entity, I am not manipulating an entity attached to Entity Framework. If I try to attach my entity to the dbContext, it fails because there is already an entity in the context with the same id.
I already thought about several solutions, but none of them please me.
Maybe am I doing something wrong in my approach? I am a little bit confused about the Repository and DAO pattern (I read anything and the very opposite about that difference on the internet).

You have two options:
initialize new dbcontext for each operation and dispose it when operation is ended:
public abstract class GenericDao<TEntity, TDomain, TDbContext> : IGenericDao<TDomain>
where TDbContext : DbContext, new()
where TEntity : class
where TDomain : class
{
protected Func<TDbContext> _contextFactory;
public GenericDao(Func<TDbContext> contextFactory)
{
_contextFactory = contextFactory;
}
public TDomain Create()
{
using(var context = _contextFactory())
{
return context.Set<TEntity>().Create();
}
}
public IList<TDomain> GetAll()
{
using(var context = _contextFactory())
{
return context.Set<TEntity>().ToList()
.Select(entity => this.ToDomain(entity)).ToList();
}
}
public void Update(TDomain domain)
{
using(var context = _contextFactory())
{
var entity = this.ToEntity(domain);
context.Attach(entity);
var entry = this._context.Entry(entity);
entry.State = EntityState.Modified;
context.SaveChanges();
}
}
public void Remove(TDomain domain)
{
using(var context = _contextFactory())
{
var entity = this.ToEntity(domain);
context.Attach(entity);
context.Set<TEntity>.Remove(entity);
context.SaveChanges();
}
}
protected abstract TDomain ToDomain(TEntity entity);
protected abstract TEntity ToEntity(TDomain domain);
}
or you can try to find entity in your instance of dbcontext using property Local of DbSet:
var contextEntity = context.Set<TEntity>().Local
.Where(c=>c.Id == entity.Id).FirstOrDefault();

You seem to be getting stuck coding to an implementation within your abstraction. If you injected an interface to your generic rather than a concrete type (like EF) then your GenericDao becomes much more flexible. You can inject whatever implementation you choose providing it implements the required interface. In your case, WCF, File, Whatever. For example;
protected IDbContext _context;
public GenericDao(IDbContext dbContext)
{
this._context = dbContext;
}
public void Remove(TDomain domain)
{
_context.Remove(this.ToEntity(domain));
}
//abstraction
public interface IDbContext
{
void Remove(Entity entity);
}
//EF Implementation
public MyEfClass : IDbContext
{
public void Remove(Entity entity)
{
//code to remove for EF example
context.Attach(entity);
context.State = EntityState.Modified;
context.Set<TEntity>.Remove(entity);
context.SaveChanges();
}
}
//WCF Implementation
public MyWCFClass : IDbContext
{
public void Remove(Entity entity)
{
//Wcf implementation here
}
}
//File example
public FileWriter : IDbContext
{
public void Remove(Entity entity)
{
LoadFile();
FindEntry(entity);
WriteFile(entity);
SaveFile();
}
public void LoadFile()
{
//use app settings for file directory
}
}

How to use Simple injector, Repository and Context - code first

I'm trying to use Simple Injector to create my repository and use it in the Business logic layer ( also i want to use PerWebRequest method ) .
In the DAL layer i have :
public interface IRepository<T> where T : class
{
void Add(T entity);
void Delete(T entity);
void Delete(int id);
void Update(T entity);
T GetById(int Id);
IQueryable<T> All();
IEnumerable<T> Find(Func<T, bool> predicate);
}
and :
public class EFRepository<T> : IRepository<T>, IDisposable where T : class
{
#region Members
protected DbContext Context { get; set; }
protected DbSet<T> DbSet { get; set; }
#endregion
#region Constructors
public EFRepository(DbContext dbContext)
{
if (dbContext == null)
throw new ArgumentNullException("dbContext");
Context = dbContext;
DbSet = Context.Set<T>();
}
and my context :
public class PASContext : DbContext, IDbContext
{
public DbSet<Product> Products { get; set; }
public DbSet<User> Users { get; set; }
public PASContext()
: base("PostAndSell")
{ }
}
As you can see EFRepository has only one constructor that takes one argument - this is because i want to use Simple Injector to create an instance of the context and pass it to the repository while it is created .
In the BLL i have a class ProductBLL and i want to get all products in that class (with some GetAll method) from the database and pass it, lets say to HomeController .
I really need someone to talk me through this .
I started by installing the right packages from the nuger (Simple Injector and Simple Injector ASP.NET Integration)
also in my global.asax.cs file, under Application_Start() function I`ve added :
var container = new SimpleInjector.Container();
container.RegisterPerWebRequest<IRepository<Product>, EFRepository<Product>>();
but where do i create the Context instance ? and how can i access it in the business layer ?

Since you will probably have many IReposotory<T> implementations (for Product, Customer, Employee, etc), it's better make a single open generic registration for IRepository<T> like this:
container.Register(typeof(IRepository<>), typeof(EFRepository<>), Lifestyle.Scoped);
Where the scoped lifestyle is defined as:
container.Options.DefaultScopedLifestyle = new WebRequestLifestyle();
This registration ensures that Simple Injector will return a EFRepository<Product>, every time a IRepository<Product> is requested, an EFRepository<Customer> for IRepository<Customer>, and so on, and so on.
Since you want the same DbContext instance to be used over all repositories within the same request, you should also register the DbContext with the scoped Lifestyle:
container.Register<DbContext, PASContext>(Lifestyle.Scoped);
In the BLL i have a class ProductBLL and i want to get all products
from the database and pass it to, lets say HomeController
In that scenario, this ProductBLL seems like a useless abstraction to me. If all it does is passing data through, you can as easily let your HomeController depend on IRepository<Product> directly.

Getting "MissingMethodException: Cannot create an instance of an interface" when binding generic interface to repository with Ninject

Following the guide here, but instead of StructureMap attempting to use Ninject.
It throws up the "MissingMethodException: Cannot create an instance of an interface" error any time I attempt to inject an IRepository<SomeEntityType> into a parameter in an action method.
Update: Also giving bootstrapper.cs not found, I used the MVC3 Ninject Nuget package.
public ActionResult Index(IRepository<SomeEntityType> repo)
{
return View();
}
NinjectWebCommon.cs
private static void RegisterServices(IKernel kernel)
{
string Cname = "VeraDB";
IDbContext context = new VeraContext("VeraDB");
kernel.Bind<IDbContext>().To<VeraContext>().InRequestScope().WithConstructorArgument("ConnectionStringName", Cname);
kernel.Bind(typeof(IRepository<>)).To(typeof(EFRepository<>)).WithConstructorArgument("context",context);
}
IRepository
public interface IRepository<T> where T : class
{
void DeleteOnSubmit(T entity);
IQueryable<T> GetAll();
T GetById(object id);
void SaveOrUpdate(T entity);
}
EFRepository
public class EFRepository<T> : IRepository<T> where T : class, IEntity
{
protected readonly IDbContext context;
protected readonly IDbSet<T> entities;
public EFRepository(IDbContext context)
{
this.context = context;
entities = context.Set<T>();
}
public virtual T GetById(object id)
{
return entities.Find(id);
}
public virtual IQueryable<T> GetAll()
{
return entities;
}
public virtual void SaveOrUpdate(T entity)
{
if (entities.Find(entity.Id) == null)
{
entities.Add(entity);
}
context.SaveChanges();
}
public virtual void DeleteOnSubmit(T entity)
{
entities.Remove(entity);
context.SaveChanges();
}
}
IEntity just acts as a generic constraint.
public interface IEntity
{
Guid Id { get; set; }
}

I made the same simple mistake. Ninject injects parameters into your constructor, but you added parameters to the Index Controller action.
It should look like this:
public class HomeController : Controller
{
private IRepository<SomeEntityType> _repo;
public HomeController(IRepository<SomeEntityType> repo)
{
_repo= repo;
}
public ActionResult Index()
{
ViewBag.Message = "Modify this template to jump-start your ASP.NET MVC application. " +
_repo.HelloWorld();
return View();
}
}
Make sense?

That sort of error usually indicates that you have a different version of the dll at runtime to the one you are referencing in the project.
Try just manually copying all the relevant dlls from your project dirs to your bin directory.
Failing that, check this (admittedly, very old) post for some ideas on how to debug the problem.

How to write generic Entity name in constructor in EF4?

i try to write Generic Repository in EF 4. But my codes is not looking good. Because ExpressionEntities is not GENERIC.
I want to convert this codes:
public class DataRepository<T> : IRepository<T> where T : class
{
private ExpressionsEntities _context;
public DataRepository()
{
}
public DataRepository(ExpressionsEntities context)
{
_context = context;
}
}
to the following:
public class DataRepository<T> : IRepository<T> where T : class
{
private GetGenericEntityCONTEXT _context;
public DataRepository()
{
}
public DataRepository(GetGenericEntityCONTEXT context)
{
_context = context;
}
}
because ExpressionsEntities not global my entities : ExpressionsEntities1, ExpressionsEntities 2, ExpressionsEntities 3 etx... i need to write get take entity for example:
public class DataRepository<T> : IRepository<T> where T : class
{
private Entity _context;
public DataRepository()
{
}
public DataRepository(Entity context)
{
_context = context;
}
public class Main
{
main()
{
new DataRepository(ExpressionEntities)
}
}
}

Not 100% sure what your asking - from what i can understand, you wan't a way to dynamically create the entity set based on T.
Well that's easy enough:
public class DataRepository<T> : IRepository<T> where T : class
{
private ObjectContext _ctx;
public DataRepository<T>(ObjectContext ctx)
{
this._ctx = ctx;
}
public IObjectSet<T> CurrentEntitySet<T>()
{
get
{
var entityName = _plularizer.Pluralize(typeof(T).Name);
string entitySetName = string.Format("{0}.{1}", EntityContainerName, entityName);
return _ctx.CreateObjectSet<T>(entitySetName );
}
}
}
Then your specific Repository could do this (for example):
public class AppleRepository : DataRepository<Apple>
{
public AppleRepository(IObjectContext ctx) : base(ctx) {}
public ICollection<Apple> FindApples(Func<Apple,bool> predicate)
{
return CurrentEntitySet.Where(predicate).ToList();
}
}
And when your creating your repository, pass through the object context - preferably by DI:
var repository = new AppleRepository(new ExpressionEntities()); // should be DI'ed
Basically, we're making use of Pluralization (the same code used by Entity Framework to pluralize entity set names), and CreateObjectSet<T>.
So if you created a DataRepository<Apple>, that would translate to an entity set name of Apples (which should match the entity set on your model), and we create an entity set based on that.
The EntityContainerName property is what's on your EDMX - you should pass this through the ctor (via DI preferably).
Does that answer your question?

I prefer to get the entityName like this.
EntityContainer container = context.MetadataWorkspace.GetEntityContainer(context.DefaultContainerName, DataSpace.CSpace);
EntitySetBase entitySet = container.BaseEntitySets.Where(item => item.ElementType.Name.Equals(typeof(T).Name)).FirstOrDefault();
var entityName = entitySet.Name
This deals with some cases if you have some classes pluralized, and some classes not.