Autofac using Constructor

Question

I use unit of work pattern with entityFramework code first. Now I want to use Autofac to register UnitOfWork, Repositories and My dbContext.

This Is my UnitOfWork code:

public class UnitOfWork : IUnitOfWork
{
    private readonly DbContext _context;

    public UnitOfWork(DbContext context)
    {
        _context = context;

        Contact = new ContractRepository(context);
    }

    public void Dispose()
    {
        _context.Dispose();
        GC.SuppressFinalize(_context);
    }

    public IContactRepository Contact { get; private set; }

    public int Complete()
    {
        return _context.SaveChanges();
    }
}

and this is my repository:

public class Repository<Entity> : IRepository<Entity> where Entity : class
{
    protected readonly DbContext _noteBookContext;
    public Repository(DbContext noteBookContext)
    {
        _noteBookContext = noteBookContext;
    }
    public void Add(Entity entity)
    {
        _noteBookContext.Set<Entity>().Add(entity);
    }
}

and this is one of my repositories:

public  class ContractRepository: Repository<Contact>,IContactRepository 
{
    public ContractRepository(DbContext noteBookContext) : base(noteBookContext)
    {

    }

    public DbContext NotebookContext
    {
        get
        {
            return _noteBookContext;
        }
    }
}

and this is my db context class:

public class NoteBookContext:DbContext
{
    public NoteBookContext(string connectionstring):base(connectionstring)
    {

    }
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Configurations.Add(new ContactConfig());
        modelBuilder.Configurations.Add(new PhoneConfig());
        modelBuilder.Configurations.Add(new PhoneTypeConfig());
        modelBuilder.Configurations.Add(new GroupConfig());
        base.OnModelCreating(modelBuilder);
    }
    public DbSet<Contact> Contacts { get; set; }
    public DbSet<Phone> Phones { get; set; }

    public DbSet<Group> Groups { get; set; }

    public DbSet<PhoneType> PhoneTypes { get; set; }
}

Now I want to register UnitOfWork with constructor (a constructor like this: )

var uow = new UnitOfWork(new NotebookdbContext("connectionstring"));

Note that NoteBookContext is my entity framework model.

I write registration but I got Error:

var builder = new ContainerBuilder();
builder.RegisterType<NoteBookContext>()
       .As<DbContext>();
builder.RegisterType<UnitOfWork>()
       .UsingConstructor(typeof(DbContext))
       .As<IUnitOfWork>();

builder.RegisterGeneric(typeof(Repository<>))
       .As(typeof(IRepository<>))
       .InstancePerLifetimeScope();

Container container = builder.Build();

This is my error:

An unhandled exception of type 'Autofac.Core.DependencyResolutionException' occurred in Autofac.dll Additional information: None of the constructors found with 'Autofac.Core.Activators.Reflection.DefaultConstructorFinder' on type 'DataLayer.NoteBookContext' can be invoked with the available services and parameters:

Cannot resolve parameter 'System.String connectionstring' of constructor 'Void .ctor(System.String)'.

Edit 2 :

after help from Cyril Durand's answer I write following registering config:

 var builder = new ContainerBuilder();
        builder.RegisterType<ConnectionStringProvider>().As<IConnectionStringProvider>();
        builder.RegisterType<NoteBookContext>().As<DbContext>().WithParameter((pi, c) => pi.Name == "connectionstring",
                                                                              (pi, c) => c.Resolve<IConnectionStringProvider>().ConnectionString);
        builder.RegisterType<UnitOfWork>().As<IUnitOfWork>().WithParameter(ResolvedParameter.ForNamed<DbContext>("connectionstring"));
        builder.RegisterGeneric(typeof(Repository<>)).As(typeof(IRepository<>)).InstancePerLifetimeScope();

and In my code :

using (var scope = DependencyInjection.Container.BeginLifetimeScope())
        {
            var ConnectionString = scope.Resolve<IConnectionStringProvider>();
            ConnectionString.ConnectionString = "Context";

            var uw = scope.Resolve<IUnitOfWork>();
            var a =uw.Contact.GetAll();

        }

but I got Error again:

An unhandled exception of type 'Autofac.Core.DependencyResolutionException' occurred in Autofac.dll

Additional information: An exception was thrown while invoking the constructor 'Void .ctor(System.String)' on type 'NoteBookContext'.

can everyone help me?

Answer 1

The error message :

An unhandled exception of type Autofac.Core.DependencyResolutionException occurred in Autofac.dll Additional information: None of the constructors found with Autofac.Core.Activators.Reflection.DefaultConstructorFinder on type DataLayer.NoteBookContext can be invoked with the available services and parameters:

Cannot resolve parameter System.String connectionstring of constructor Void .ctor(System.String).

tells you that Autofac can't create a NoteBookContext because it can't resolve a parameter named connectionstring of type String.

Your NoteBookContext implementation needs a connectionstring, Autofac can't know it without you telling it. When you register the NoteBookContext you will have to specify the connectionstring :

builder.RegisterType<NoteBookContext>()
       .As<DbContext>()
       .WithParameter("connectionstring", "XXX");

Another solution with dynamic resolution and a IConnectionStringProvider interface :

public interface IConnectionStringProvider
{
    public String ConnectionString { get; }
}

and registration :

builder.RegisterType<ConnectionStringProvider>()
       .As<IConnectionStringProvider>()
       .InstancePerLifetimeScope(); 
builder.RegisterType<NoteBookContext>()
       .As<DbContext>()
       .WithParameter((pi, c) => pi.Name == "connectionstring", 
                      (pi, c) => c.Resolve<IConnectionStringProvider>().ConnectionString)
       .InstancePerLifetimeScope();