How should I use IoC DI with this repository pattern?

问题

I am using the repository pattern found in the answer to this SO question:

Advantage of creating a generic repository vs. specific repository for each object?

Namely, each repository inherits from an abstract base class that contains generic methods like add, delete, etc. and also implements a specific repository interface for any methods that are unique to that repository/entity.

ie.

public class CompanyRepository : Repository<Company>, ICompanyRepository {
...
}

In my business layer I am using Structure Map to get an instance of the repository, but I am unsure how to use it.

 // Structure Map initialisation
 ObjectFactory.Initialize(
 x =>
 {                    
      x.For<ICompanyRepository>().Use<CompanyRepository>();
 });

resolving an instance:

return ObjectFactory.GetInstance<ICompanyRepository>();

However the instance I get is an interface and not the whole repository implementation. I don't have access to the methods on the base class (Repository<Company>). What is the usual way to do this?

回答1:

The key here is to think of Repository<> solely as an implementation detail. You won't be accessing any methods on it directly; instead, you will expose all methods, including Insert and Delete, on the interface:

public interface ICustomerRepository
{
    // ...Customer-specific queries...

    void Insert(Customer customer);

    void Delete(Customer customer);
}

When you implement the interface in CustomerRepository, you simply have to pass the Insert and Delete calls through to the protected methods of Repository<> as discussed in the original question.

The StructureMap registration you state in the question is exactly what I would expect. The purpose of Repository<> then is to aid in the implementation of entity-specific interfaces. Keep in mind that the interfaces will always contain the repository's full public API and that should point you in the right direction.

回答2:

Why not

return ObjectFactory.GetInstance<Repository<Company>>;

? You will have to modify accordingly your ObjectFactory initialization:

// Structure Map initialisation
ObjectFactory.Initialize(
    x => {                    
      x.For<Repository<Company>>().Use<CompanyRepository>();
    });

EDIT
If you still want to get Repository<Company> also for ICompanyRepository, you need to declare a forwarding:

// Structure Map initialisation
ObjectFactory.Initialize(
    x => {                    
      x.For<Repository<Company>>().Use<CompanyRepository>();
      x.Forward<Repository<Company>, ICompanyRepository>();
    });

来源：https://stackoverflow.com/questions/4312388/how-should-i-use-ioc-di-with-this-repository-pattern

标签

design-patterns

ioc-container

repository-pattern