Question

我正在使用API来实现某些服务。

我收到错误：

InvalidOperationException：尝试激活“Zipcode_Service.Controllers.CityController”时，无法解析类型“Zipcode_Service.Models.IZipcodeRepository”的服务。

我的cotroller的构造函数或_repository的减速导致了这个问题：

    private IZipcodeRepository _repository;
    public CityController(ILogger<CityController> logger, IZipcodeRepository repository)
    {
        _logger = logger;
        _repository = repository;
    }

我的界面：

public interface IZipcodeRepository
{
    IEnumerable<City> GetCitiesByCityName(string cityName);
  //  City GetCityNameById(int cityId);
}

我的ZipcodeRepository：

public class ZipcodeRepository : IZipcodeRepository
{
    private ZipcodeContext _context;
    private ILogger<ZipcodeRepository> _logger;

    public ZipcodeRepository(ZipcodeContext context, ILogger<ZipcodeRepository> logger)
    {
        _context = context;
        _logger = logger;
    }

    public IEnumerable<City> GetCitiesByCityName(string cityName)
    {
       return _context.Cities.Where(t => t.Name.Contains(cityName)).ToList();
    }

我看到很多类似的问题，大多数人都提出问题出在控制器中，使用的是存储库，而不是接口。事实并非如此。

编辑：更多信息
我的启动页面：

  public Startup(IHostingEnvironment env)
    {
        _env = env;
        var builder = new ConfigurationBuilder()
            .SetBasePath(env.ContentRootPath)
            .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
            .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
            .AddEnvironmentVariables();
        _config = builder.Build();
    }

    public void ConfigureServices(IServiceCollection services)
    {
        // Add framework services.
        services.AddMvc();
        services.AddDbContext<ZipcodeContext>();
        services.AddScoped<IZipcodeRepository, ZipcodeRepository>();

    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
    {
    ...
        app.UseMvc(config =>
        {
            config.MapRoute(
                name: "Default",
                template: "{controller}/{action}/{id?}",
                defaults: new { controller = "App", action = "Index" }
                );

我的上下文类：

    public ZipcodeContext(IConfigurationRoot config, DbContextOptions options) : base(options)
    {
        _config = config;
    }
    public DbSet<City> Cities { get; set; }
    public DbSet<Zipcode> Zipcodes { get; set; }
    public DbSet<Street> Streets { get; set; }


    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        base.OnConfiguring(optionsBuilder);
        optionsBuilder.UseSqlServer(_config["ConnectionStrings:ZipcodeContextConnection"]);
    }

Answer 1

当容器尝试解析对象图以满足依赖关系时，问题通常与错误相关。

您在评论中表明您注册了IZipcodeRepository

services.AddScoped<IZipcodeRepository, ZipcodeRepository>();

大。但是，在尝试初始化实现ZipcodeRepository或其中一个依赖项时，也会发生该错误。例如，如果ZipcodeContext在初始化时抛出异常，则会导致同样的问题。

确保上下文也已正确配置。

例如

services.AddDbContext<ZipcodeContext>(options =>
    options.UseSqlServer(Configuration.GetConnectionString("ConnectionNameHere")));

C＃无法解析类型上下文的服务

1 个答案: