ASP.NET MVC通用存储库的实现和用法

Question

I've decided to develop a generic repository inside my ASP.NET MVC application, nevertheless I have some issues with implementation. I will try to describe my problem below.

This is my generic repository:

public interface IGenericRepository<T> where T : class
{
    IQueryable<T> GetAll();
    IQueryable<T> FindBy(Expression<Func<T, bool>> predicate);
    void Add(T entity);
    void Delete(T entity);
    void Edit(T entity);
    void Save();
}

public interface IArtistRepository : IGenericRepository<Artist>
{
    Artist GetSingle(int fooId);
}

public abstract class GenericRepository<C, T> : IGenericRepository<T> where T : class where C : DbContext, new()
{
    public C Context { get; set; } = new C();

    public virtual IQueryable<T> GetAll()
    {
       IQueryable<T> query = Context.Set<T>();
       return query;
    }

    public IQueryable<T> FindBy(System.Linq.Expressions.Expression<Func<T, bool>> predicate)
    {
       IQueryable<T> query = Context.Set<T>().Where(predicate);
       return query;
    }

    public virtual void Add(T entity)
    {
       Context.Set<T>().Add(entity);
    }

    public virtual void Delete(T entity)
    {
       Context.Set<T>().Remove(entity);
    }

    public virtual void Edit(T entity)
    {
       Context.Entry(entity).State = EntityState.Modified;
    }

    public virtual void Save()
    {
       Context.SaveChanges();
    }
}

Concrete implementations:

public class ArtistRepository :
      GenericRepository<MusicContextSqlServer, Artist>, IArtistRepository
{

    public Artist GetSingle(int artistId)
    {
       var query = GetAll().FirstOrDefault(x => x.ArtistId == artistId);
       return query;
    }
}    

Now when building controller, let's take Artist controller as example:

This will be the constructor:

public class ArtistsController : Controller
{
     private readonly IArtistRepository _artistRepo;

     public ArtistsController(IArtistRepository artistRepo)
     {
         _artistRepo = artistRepo;
     }
}

Now when it comes to Get artists, I could use:

public ActionResult Index()
{
    var model = _artistRepo.GetAll();
    return View(model.ToList());
}

however I also need to include ArtistDetails dbset, normally using context embedded inside controller I could do like this:

(db is in this case normal context embedded in controller)

public ActionResult Index()
{
    var artist = db.Artist.Include(a => a.ArtistDetails);                     
    return View(artist.ToList());
}

But after using repositories, I am not sure where could I add this Include() function to make it work along my repositories. At the moment I can just do GetAll() coming from my repository. Same situation with call to db.ArtistDetails inside SelectList.

Same situation is with Create , normally I would use: (db is in this case normal context embedded in controller)

public ActionResult Create()
{
     ViewBag.ArtistId = new SelectList(db.ArtistDetails, "ArtistId", "Bio");       
     return View();       
}

public ActionResult Create([Bind(Include = "ArtistId,Name")] Artist artist)
{
      if (ModelState.IsValid)
      {
          db.Artist.Add(artist);
          db.SaveChanges();
          return RedirectToAction("Index");
      }

      ViewBag.ArtistId = new SelectList(db.ArtistDetails, "ArtistId", "Bio", artist.ArtistId);

       return View(artist);
}

How can I convert those methods using repositories I use. Summarizing how to change those methods after I implemented my repository, where should I make changes and how it would look like, could anybody show solution as an answer. Thanks.

Answer 1

Since you inherit a public property Context , which will be available for artist repository to use. I would introduce another method to Artist repository as below:

public Artist GetSingleWithDetails(int artistId)
    {
       return = Context.Set<Artist>().Include(a => a.ArtistDetails).FirstOrDefault(x => x.ArtistId == artistId);

    }

Ideally Context property should be protected so that its available to subclasses but not available publicly

EDIT : For ArtistDetailsRepository to GetAll ArtistDetails

Interface:

public interface IArtistDetailsRepository : IGenericRepository<ArtistDetails>
{        
}

Repository:

public class ArtistDetailsRepository :
      GenericRepository<MusicContextSqlServer, ArtistDetails>, IArtistDetailsRepository
{   
}    

Create:

ViewBag.ArtistId = new SelectList(artistDetailRepository.GetAll.ToList(), "ArtistId", "Bio", artist.ArtistId);