假設建立了一個 DbContext 叫做 TempDbContext
public class TempDbContext : DbContext
{
public TempDbContext(DbContextOptions<TempDbContext> options) : base(options)
{
}
public DbSet<Product> Products { get; set; }
}
{
public TempDbContext(DbContextOptions<TempDbContext> options) : base(options)
{
}
public DbSet<Product> Products { get; set; }
}
IRepository<T> 為一些常用操作(例如CRUD)的 interface
IProductRepository 為操作 Product 的 interface，並包含了IRepository<T>
public interface IRepository<T> where T : class
{
IEnumerable<T> GetAll();
IEnumerable<T> Find(Func<T, bool> predicate);
T GetById(int id);
void Create(T entity);
void Update(T entity);
void Detele(T entity);
int Count(Func<T, bool> predicate);
}
public interface IProductRepository : IRepository<Product>
{
// 一些操作 Product 的方法
Product GetProductByName(string name);
}
實作 IRepository<T>
public class Repository<T> : IRepository<T> where T : class
{
// 會利用 ASP.NET Core 2.0 的 DI 注入實例
protected readonly TempDbContext _context;
public Repository(TempDbContext context)
{
_context = context;
}
public void Save() => _context.SaveChanges();
public int Count(Func<T, bool> predicate)
{
return _context.Set<T>().Where(predicate).Count();
}
public void Create(T entity)
{
_context.Add(entity);
Save();
}
public void Detele(T entity)
{
_context.Remove(entity);
Save();
}
public IEnumerable<T> Find(Func<T, bool> predicate)
{
return _context.Set<T>().Where(predicate);
}
public IEnumerable<T> GetAll()
{
return _context.Set<T>();
}
public T GetById(int id)
{
return _context.Set<T>().Find(id);
}
public void Update(T entity)
{
_context.Entry(entity).State = EntityState.Modified;
Save();
}
}
{
// 會利用 ASP.NET Core 2.0 的 DI 注入實例
protected readonly TempDbContext _context;
public Repository(TempDbContext context)
{
_context = context;
}
public void Save() => _context.SaveChanges();
public int Count(Func<T, bool> predicate)
{
return _context.Set<T>().Where(predicate).Count();
}
public void Create(T entity)
{
_context.Add(entity);
Save();
}
public void Detele(T entity)
{
_context.Remove(entity);
Save();
}
public IEnumerable<T> Find(Func<T, bool> predicate)
{
return _context.Set<T>().Where(predicate);
}
public IEnumerable<T> GetAll()
{
return _context.Set<T>();
}
public T GetById(int id)
{
return _context.Set<T>().Find(id);
}
public void Update(T entity)
{
_context.Entry(entity).State = EntityState.Modified;
Save();
}
}
實作 IProductRepository，也繼承 Repository<Product>
public class ProductRepository : Repository<Product>, IProductRepository
{
public ProductRepository(TempDbContext context) : base(context)
{
}
public Product GetProductByName(string name)
{
return _context
.Products
.Where(p => p.Name == name)
.FirstOrDefault();
}
}
{
public ProductRepository(TempDbContext context) : base(context)
{
}
public Product GetProductByName(string name)
{
return _context
.Products
.Where(p => p.Name == name)
.FirstOrDefault();
}
}
ASP.NET Core 2.0 DI 設定(Startup)
public void ConfigureServices(IServiceCollection services)
{
// Repository 建構子需要 DbContext
services.AddDbContext<TempDbContext>(options => options.UseInMemoryDatabase("TempContext"));
services.AddTransient<IProductRepository, ProductRepository>();
services.AddMvc();
}
{
// Repository 建構子需要 DbContext
services.AddDbContext<TempDbContext>(options => options.UseInMemoryDatabase("TempContext"));
services.AddTransient<IProductRepository, ProductRepository>();
services.AddMvc();
}
在 Controller 中使用 Repository
[Route("api/[controller]")]
public class ProductController : Controller
{
private readonly IProductRepository _productRepository;
public ProductController(IProductRepository productRepository)
{
_productRepository = productRepository;
}
}
public class ProductController : Controller
{
private readonly IProductRepository _productRepository;
public ProductController(IProductRepository productRepository)
{
_productRepository = productRepository;
}
}
==========
Debug：
在執行時發生了這個錯誤
確定在ConfigureServices有設定DbContext的注入，後來發現是TempDbContext的建構子忘了呼叫base(options)Additional information: No database provider has been configured for this DbContext. A provider can be configured by overriding the DbContext.OnConfiguring method or by using AddDbContext on the application service provider. If AddDbContext is used, then also ensure that your DbContext type accepts a DbContextOptions object in its constructor and passes it to the base constructor for DbContext.
