Register Generic Type with Autofac

Question

I have UnitofWork class and it implement IUnitOfWork. I try to register that with autofac :

var builder = new ContainerBuilder();
builder
    .RegisterGeneric(typeof(UnitOfWork<Repository<>,>))
    .As(typeof(IUnitOfWork))
    .InstancePerDependency();

Implementation is:

public class UnitOfWork<T, O> : IUnitOfWork
    where T : Repository<O>
    where O : BaseEntity
{
}

public interface IUnitOfWork : IDisposable
{
    void SaveChanges();
}

Gives an error "Type expected"

but this one work on another project:

public class Repository<T> : GenericRepository<T> 
    where T : BaseEntity
{
    public Repository(IDbContext context)
        : base(context) { }   
}

public abstract class GenericRepository<T> 
    : IRepository<T>, IQueryable<T> where T : BaseEntity
{
}

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

Answer 1

You cannot have partially opened classes (e.g. with UnitOfWork<Repository<>,> you have specified T but not O) inside a typeof, try it with:

var builder = new ContainerBuilder();
builder
    .RegisterGeneric(typeof(UnitOfWork<,>))
    .As(typeof(IUnitOfWork))
    .InstancePerDependency();

The where T : Repository<O> generic constraint will take care of that the first argument should be an Repository<>

But it won't work with RegisterGeneric because it requires a generic interface so need to create a IUnitOfWork<T,O>…

But your model is very strange. Why does your UnitOfWork need a Repository<> type argument?

Instead of having it as a type argument you can get an Repository<> in your UnitOfWork<E> constructor:

public class UnitOfWork<E> : IUnitOfWork<E> where E : BaseEntity
{
    private readonly Repository<E> repository;

    public UnitOfWork(Repository<E> repository)
    {
        this.repository = repository;
    }

    //.. other methods

}

Where IUnitOfWork<E>

public interface IUnitOfWork<E> : IDisposable where E : BaseEntity
{
    void SaveChanges();
}

And the Autofac registration:

var builder = new ContainerBuilder();
builder
    .RegisterGeneric(typeof(Repository<>)).AsSelf();
builder
    .RegisterGeneric(typeof(UnitOfWork<>))
    .As(typeof(IUnitOfWork<>))
    .InstancePerDependency();
var container = builder.Build();

// sample usage
var u = container.Resolve<IUnitOfWork<MyEntity>>();