.net Core 3 / API / DI / 存储库模式

Question

我正在尝试在 .net Core 中创建 Web API。我希望这个 API 调用一个 DLL，其中实现了存储库设计模式。在这整个过程中，我尝试使用依赖注入，但我在管理存储库中数据库的上下文时遇到了一些问题。

我希望每个调用 API.

的上下文一个新的上下文

当我尝试执行我的代码时，在 CreateHostBuilder(args).Build().运行(); 行出现异常在 Main.

这个例外是：

'Some services are not able to be constructed' InvalidOperationException : Unable to resolve service for type 'BX_Security_AccessBase.Context.SecurityContext' while attempting to activate 'BX_Security_AccessBase.Repository.UsersRepository'.

我知道代码不完整，不能完全工作，但至少它应该比实际更晚破解。我想我在架构上犯了一个错误。

下面有很多代码，但我无法找出我的问题。

谢谢大家

在我的 API 我有：

Startup.cs

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddControllers();

        services.AddScoped<IUsersRepository, UsersRepository>();
        services.AddScoped<IUserService, UserService>();
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseHttpsRedirection();

        app.UseRouting();

        app.UseAuthorization();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllers();
        });
    }
}

User.cs

public class User
{
    public User() {}

    public int UserId { get; set; }
    public string LastName { get; set; }
    public string FirstName { get; set; }
    public DateTime Birthdate { get; set; }
}

UserService.cs

public class UserService : IUserService
{
    private readonly AppSettings _appSettings;
    private readonly IUsersRepository _userRepository;

    public UserService(IOptions<AppSettings> appSettings, IUsersRepository userRepository)
    {
        _appSettings = appSettings.Value;
        _userRepository = userRepository;

    }

    public IEnumerable<User> GetAll()
    {
        return _userRepository.GetAllUsers().Select(u=> new User());
    }
}

我UserService.cs

public interface IUserService
{
    public IEnumerable<User> GetAll();
}

AppSettings.cs

 public class AppSettings
{
    public string Secret { get; set; }
}

UsersController.cs

[Route("api/[controller]")]
[ApiController]
public class UsersController : ControllerBase
{
    private IUserService _userService { get; }

    public UsersController(IUserService userService)
    {
        _userService = userService;
    }

    [HttpGet]
    public IActionResult GetAll()
    {
        var users = _userService.GetAll();
        return Ok(users);
    }
}

在我的 DLL 中：

SecurityContext.cs

public partial class SecurityContext : DbContext
{
    public SecurityContext(DbContextOptions<SecurityContext> options) : base(options) { }

    public DbSet<Users> Users { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        if (!optionsBuilder.IsConfigured)
        {
            optionsBuilder.UseSqlServer("Data Source=; Database=BXDB; User Id=sa; Password=;");
        }
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Users>(entity =>
        {
            entity.HasKey(e => e.UserId).HasName("PK_User_UserId");

            entity.ToTable("Users", "sec");

            entity.Property(e => e.Birthdate).HasColumnType("date");

            entity.Property(e => e.FirstName)
                .HasMaxLength(50)
                .IsUnicode(false);

            entity.Property(e => e.LastName)
                .HasMaxLength(50)
                .IsUnicode(false);
        });

        OnModelCreatingPartial(modelBuilder);
    }

    partial void OnModelCreatingPartial(ModelBuilder modelBuilder);
}

Users.cs

public class Users
{
    public Users() { }

    public int UserId { get; set; }
    public string LastName { get; set; }
    public string FirstName { get; set; }
    public DateTime Birthdate { get; set; }
}

IUsersRepository.cs

public interface IUsersRepository
{
    public IQueryable<Users> GetAllUsers();
}

UsersRepository.cs

public class UsersRepository : IUsersRepository
{
    public readonly SecurityContext _dbContext;

    public UsersRepository(SecurityContext dbContext)
    {
        _dbContext = dbContext;
    }

    public IQueryable<Users> GetAllUsers()
    {
        return _dbContext.Users;
    }
}

Answer 1

'Some services are not able to be constructed' InvalidOperationException : Unable to resolve service for type 'BX_Security_AccessBase.Context.SecurityContext' while attempting to activate 'BX_Security_AccessBase.Repository.UsersRepository'.

根据错误，您应该按如下方式将 DbContext 注册为服务：

public void ConfigureServices(IServiceCollection services)
{ 
        var connection = @"Server=(localdb)\mssqllocaldb;Database=BXDB;Trusted_Connection=True;ConnectRetryCount=0";
        services.AddDbContext<DLL.Models.SecurityContext>(options => options.UseSqlServer(connection, x => x.MigrationsAssembly("DLL")));

        services.AddControllers();

        services.AddScoped<IUsersRepository, UsersRepository>();
        services.AddScoped<IUserService, UserService>();
 }

.net Core 3 / API / DI / 存储库模式

.net Core 3 / API / DI / Repository pattern

api

dependency-injection

repository

asp.net-core