Question

我正在使用ASP.NET Core开发Web API。当我使用post请求执行我的API时，在 UnitController 的Post方法中的断点之前抛出异常。

异常

请求启动HTTP / 1.1 POST http://localhost:5000/api/unit application / json 31失败：Microsoft.AspNetCore.Server.Kestrel [13] 连接ID“0HKVTL9A1LTD4”：应用程序抛出了未处理的异常。 System.InvalidOperationException：尝试激活“Project.Service.UnitService”时无法解析类型“Project.DataAccess.Repository.UnitRepository”的服务。

上下文

namespace Project.DataAccess.Library.Interface {
public interface IBaseRepository<M> where M : class, IEntity
{
    IEnumerable<M> SelectAll();

    M SelectByID(int id);

    void Insert(M obj);

    void Update(M obj);

    void Delete(int id);

    void Save();
}
}

namespace Project.DataAccess.Library {
public abstract class BaseRepository<M> : IBaseRepository<M> where M : class, IEntity
{
    protected ProjectContext Db { get; }
    private DbSet<M> table = null;

    protected DbSet<M> Table
    {
        get
        {
            return this.table;
        }
    }

    public BaseRepository(ProjectContext dbContext)
    {
        Db = dbContext;
        this.table = Db.Set<M>();
    }

    public void Delete(int id)
    {
        M existing = this.SelectByID(id);
        if (existing != null)
            this.table.Remove(existing);
    }

    // others methods
}
}

namespace Project.DataAccess.Repository
{
    public class UnitRepository : BaseRepository<Unit>, IUnitRepository
    {
        public UnitRepository(Projectcontext) : base(context) { }
    }
}

namespace Project.Service
{
    public class UnitService : BaseService<Unit>, IUnitService
    {
        public UnitService(UnitRepository unitRepository) : base(unitRepository) { }
    }
}


namespace AssoManager.Service.Library
{
    public abstract class BaseService<M> : IBaseService<M> where M : class, IEntity
    {
        private IBaseRepository<M> _repository;

        public BaseService(IBaseRepository<M> repository)
        {
            _repository = repository;
        }

        public IEnumerable<M> GetAll()
        {
            return this._repository.SelectAll();
        }
    }
 }


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

        public IConfigurationRoot Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            // Add framework services.
            services.AddMvc();

            this.DataAccessMySqlConfiguration(services);
            this.ConfigureRepository(services);
            this.ConfigureServicesUnit(services);
            this.ConfigureServicesUser(services);
        }

        // 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)
        {
            loggerFactory.AddConsole(Configuration.GetSection("Logging"));
            loggerFactory.AddDebug();

            app.UseMvc();
        }

        #region Database configuration

        public void DataAccessMySqlConfiguration(IServiceCollection services)
        {
            services.AddDbContext<ProjectContext>(options => options.UseMySQL(Configuration.GetConnectionString("MsSQLConnection")));
        }

        #endregion

        #region DataAccess configuration

        public void ConfigureRepository(IServiceCollection services)
        {
            services.AddScoped<IUnitRepository, UnitRepository>();
            services.AddScoped<IUserRepository, UserRepository>();
        }

        #endregion

        #region Services configuration

        /// <summary>
        /// Is used to add unit services to the container
        /// </summary>
        public void ConfigureServicesUnit(IServiceCollection services)
        {
            services.AddTransient<IUnitService, UnitService>();
            services.AddTransient<IMeetingService, MeetingService>();
        }

        /// <summary>
        /// Is used to add user services to the container
        /// </summary>
        public void ConfigureServicesUser(IServiceCollection services)
        {
            services.AddTransient<IUserService, UserService>();
        }

        #endregion Services configuration
    }
}


namespace Project.Controllers
{
    [Route("api/[controller]")]
    public class UnitController : Controller
    {
        private IUnitService UnitService;

        public UnitController(IUnitService unitService)
        {
            UnitService = unitService;
        }

        // GET api/units
        [HttpGet]
        public IEnumerable<Unit> Get()
        {
            return UnitService.GetAll();
        }

        // GET api/unit/5
        [HttpGet("{id}")]
        public IActionResult Get(int id)
        {
            Unit unit;
            //->Check
            if (id < 1)
                return BadRequest();
            //->Processing
            unit = UnitService.GetByID(id);
            if (unit == null)
                return NotFound();
            return new ObjectResult(unit);
        }

        // POST api/unit
        [HttpPost]
        public IActionResult Post([FromBody]Unit unit)
        {
            //->Check
            if (unit == null)
                return BadRequest();
            //->Processing
            UnitService.Create(unit);
            return CreatedAtRoute("Get", new { id = unit.Id }, unit);
        }

        // PUT api/unit/5
        [HttpPut("{id}")]
        public void Put(int id, [FromBody]string value)
        {
        }

        // DELETE api/unit/5
        [HttpDelete("{id}")]
        public void Delete(int id)
        {
        }
    }
}

版本

"dependencies": {
    "Microsoft.NETCore.App": {
      "version": "1.0.0",
      "type": "platform"
    },
    "Microsoft.AspNetCore.Mvc": "1.0.0",
    "Microsoft.AspNetCore.Server.Kestrel": "1.0.0",
    "Microsoft.Extensions.Configuration.EnvironmentVariables": "1.0.0",
    "Microsoft.Extensions.Configuration.FileExtensions": "1.0.0",
    "Microsoft.Extensions.Configuration.Json": "1.0.0",
    "Microsoft.Extensions.Logging": "1.0.0",
    "Microsoft.Extensions.Logging.Console": "1.0.0",
    "Microsoft.Extensions.Logging.Debug": "1.0.0",
    "Microsoft.Extensions.Options.ConfigurationExtensions": "1.0.0",
    "Microsoft.EntityFrameworkCore": "1.0.0",
    "MySql.Data.Core": "7.0.4-IR-191",
    "MySql.Data.EntityFrameworkCore": "7.0.4-IR-191",
    "IdentityServer4": "1.0.0-rc2",
    "AssoManager.Domain": "1.0.0-*",
    "AssoManager.Service": "1.0.0-*",
    "AssoManager.DataAccess": "1.0.0-*"
  },

问题

我认为问题可能在于BaseRepository和IBaseRepository之间的继承。但我不明白我的错误在哪里。我该如何纠正这个错误？

感谢您的帮助:)，

Answer 1

您正在将UnitRepository注册为IUnitRepository，但请求您的IoC解析UnitRepository。它没有注册，所以它失败了。

尝试使UnitService采用IUnitRepository而不是UnitRepository来解决问题（原谅双关语）。

Answer 2

我发现Callum Bradbury的答案非常有用（谢谢，Callum），但是我认为更通用的答案可能适用于不同情况。所以：

当您在给定的类中使用DI（依赖项注入），并且还使用IoC（控制反转）容器来统治所有依赖项时（这不是必需的，但这是常见的情况），您必须确保， 每个可注射依赖项都在容器中注册，并且-可能-这通常是递归问题。

示例，查找以下伪代码：

merge into t1 trg
using
(
    select  lower_range, upper_range, rate
    from    t2
) src
on ( trg.days between src.lower_range and src.upper_range )
when matched then update
set trg.rate = src.rate
where lnnvl(trg.rate = src.rate);

System.InvalidOperationException：无法解析类型

2 个答案: