Im learning about generics and was wondering about how a generic controller, service and ef core repo design would look like.

My case: lets say an incomming post request to add Smartphone and keyboard object to smartphone and keyboard tables

My repository setup is

    public class GenericRepository<TEntity> : IGenericRepository<TEntity>
                where TEntity : class, IProductGenericEntities
{
    private readonly MyDbContext _db;
    public GenericRepository(MyDbContext db)
    {
        _db = db;
    }

    public async Task<bool> AddProduct(TEntity entity)
    {
        try
        {
            _db.Set<TEntity>().AddAsync(entity);
            return (await _db.SaveChangesAsync()) > 0;
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex.Message);
            return false;
        }
    }
}

And my service

    public class ProductService<TEntity> : IProductService<TEntity>
            where TEntity : class
{
    private readonly IGenericRepository<TEntity> _repo;

    public ProductService(IGenericRepository<TEntity> repo)
    {
        _repo = repo;
    }


    public async Task<bool> AddProduct(TEntity entity)
    {
        return await _repo.AddProduct(entity);
    }

}

And my Controller.cs

    [ApiController]
[Route("api/[controller]")]
public class ProductController
{
    private readonly IProductService<Keyboards> _keyService;
    private readonly IProductService<Smartphones> _smartService;

    public ProductController(IProductService<Keyboards> keyService, IProductService<Smartphones> smartService)
    {
        _keyService = keyService;
        _smartService = smartService;
    }

    [HttpPost("Post-generated-items")]
    public async Task<ActionResult> PostProducts(List<TEntity> entities)
    {
        foreach(var item in entities)
        {
            and sort the objects here
        }
        
    }
}

is it correct to initialize 2 of IProductServices and sort the incomming objects to their correct DI on the controller?

    private readonly IProductService<Keyboards> _keyService;
private readonly IProductService<Smartphones> _smartService;

Is there a way to make it more automatic by detecting incomming object type and then initilize it all the way to repo so i dont need 2 of IProductService<>?

Or is it what im doing plain wrong with a generic service layor?

CodePudding user response：

Ok, so your approach is completely valid, i would not worry about initializing two repositories, since they're essentially empty memory vise since they just take reference to existant DbContext which by default is registered with Scoped lifecycle.

There will be a time when you need to use several repositories to complete task at hand. I would suggest going for NON-generic services approach. This way you could make ProductsService which has all the needed generic repositories injected and can orchestrate their work to achieve use case goal.

You might as well look into UOW (Unit Of Work) pattern for even more complex situations.

Answering your question:

Is there a way to make it more automatic by detecting incomming object type and then initilize it all the way to repo so i dont need 2 of IProductService<>?

You might write some code that would do just that for you using Reflection, but i would suggest against doing so. By initializing your repositories specifically you make yourself less error prone and code becomes more self-documenting.

For example now you have a controller that asks DI for two services and that instantly set's you up for what's going on in this controller. On the other hand if everything would be generic, you would end up with one huge knot of spaghetti that "Does everything".