Why is the [HttpPost("addproduct")] method not working? - asp.net-mvc

Question

How can I fix errors in ProductsContoller.cs and ProductRepository.cs files?
IGenericRepository
namespace API.Core.Interfaces
{
public interface IGenericRepository<T> where T : BaseEntity
{
T Add(T entity);
}
}
GenericRepository
namespace API.Infrastructure.Implements
{
public class GenericRepository<T> : IGenericRepository<T> where T : BaseEntity
{
private readonly StoreContext _context;
public GenericRepository(StoreContext context)
{
_context = context;
}
public T Add(T entity)
{
_context.Set<T>().Add(entity);
_context.SaveChanges();
return entity;
}
}
}
Error1
ProductsController
(field) IGenericRepository ProductsController._productAddRepository
CS1061: 'Product' does not contain a definition for 'GetAwaiter' and no accessible extension
method 'GetAwaiter' accepting a first argument of type 'Product' could be found
(are you missing a using directive or an assembly reference?)
namespace API.Controllers
{
public class ProductsController : BaseApiController
{
private IGenericRepository<Product> _productAddRepository;
private readonly IGenericRepository<Product> _productRepository;productRepository,
public ProductsController(IGenericRepository<Product> productRepository,
IGenericRepository<Product> productAddRepository,
IMapper mapper)
{
// _productAddRepository = productAddRepository;
_productRepository = productRepository;
}
[HttpPost("addproduct")]
public async Task<ActionResult<Product>> AddProduct(Product product)
{
**var data = await _productAddRepository.Add(product);**
return Ok();
}
}
}
IProductRepository
namespace API.Core.Interfaces
{
public interface IProductRepository
{
Task<Product> AddProductAsync(Product product);
}
}
ProductRepository
Error2
(awaitable) Task DbContext.SaveChangesAsync([System.Threading. Cancellation Token cancellation Token = default]) (+ 1 overload)
Saves all changes made in this context to the database.
This method will automatically call Microsoft.Entity FrameworkCore.Change Tracking.Change Tracker.DetectChanges() to
discover any changes to entity instances before saving to the underlying database.
This can be disabled via Microsoft.Entity Framework Core.ChangeTracking.ChangeTracker.AutoDetectChangesEnabled.
Multiple active operations on the same context instance are not supported. Use 'await' to
ensure that any asynchronous operations have completed before calling another method on this context.
Returns:
A task that represents the asynchronous save operation. The task result contains the number of state entries written to the database.
Exceptions:
DbUpdateException
DbUpdateConcurrencyException
CS0029: Cannot implicitly convert type 'int' to 'API.Core.DbModels.Product'.
namespace API.Infrastructure.Implements
{
public class ProductRepository : IProductRepository
{
private readonly StoreContext _context;
public ProductRepository(StoreContext context)
{
_context = context;
}
public async Task<Product> AddProductAsync(Product product)
{
var newBrand = new Product()
{
PictureUrl=product.PictureUrl,
Name = product.Name,
Description=product.Description,
ProductType=product.ProductType,
ProductBrand=product.ProductBrand
};
_context.Products.Add(newBrand);
**return await _context.SaveChangesAsync();**
}
}
}

Answer 1

You're call stack looks like:
Task<ActionResult<List<Product>>> AddProduct(Product product)
// you can't await Add()
var data = await _productAddRepository.Add(product);
// Add is not async
T Add(T entity)
You can't await Add() it's not async:
public T Add(T entity)
{
_context.Set<T>().Add(entity);
_context.SaveChanges();
return entity;
}
If you want this to work, you need to change the code so that Add() is async:
public async TaskT<T> Add(T entity)
{
_context.Set<T>().Add(entity);
await _context.SaveChangesAsync();
return entity;
}
Async Return Types:
Async methods can have the following return types:
Task, for an async method that performs an operation but returns no value.
Task, for an async method that returns a value.
void, for an event handler.
Any type that has an accessible GetAwaiter method. The object returned by the GetAwaiter method must implement the System.Runtime.CompilerServices.ICriticalNotifyCompletion interface.
IAsyncEnumerable, for an async method that returns an async stream.
The return type of Add() is T, which is not one of the previous requirements.