System.InvalidOperationException：无法解析类型的服务 [重复]

Posted 2023-03-30

【中文标题】System.InvalidOperationException：无法解析类型的服务 [重复]

【英文标题】：System.InvalidOperationException: Unable to resolve service for type [duplicate]

【发布时间】：2016-10-26 14:52:56

【问题描述】：

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

例外

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

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:)，

【参考方案1】：

您将 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。

尝试让 UnitService 采用 IUnitRepository 而不是 UnitRepository，这应该可以解决问题（请原谅双关语）。

【讨论】：

谢谢。我编辑我的帖子。编写的异常没有完成.. 抱歉！

【参考方案2】：

我发现 Callum Bradbury 的答案非常有用（谢谢，Callum），但我认为更一般的答案可能适用于不同的情况。所以：

当您在给定类中使用 DI（依赖注入）以及 IoC（控制反转）容器来管理所有依赖项（这不是必需的，但这是一种常见情况）时，您必须确定， 每个可注入的依赖项都在容器中注册，并且 - 可能 - 这通常是一个递归问题。

示例，请查找以下伪代码：

// A class which uses injected dependencies
class NeedSomeDependeciesToBeInjected

    public NeedSomeDependeciesToBeInjected (
        IThisIsReallyImportant important,
        IThisIsUsefulButNotImportant useful) 


// A complex dependency, which requires other injected dependency
// (So, yes, recursion...)
class ThisIsReallyImportant : IThisIsReallyImportant

    public ThisIsReallyImportant (
        IThisIsRequiredToBecomeImportant required) 


// A dependency, which does not require other injected dependency,
// but is required for another dependency
class ThisIsRequiredToBecomeImportant : IThisIsRequiredToBecomeImportant 

    public ThisIsRequiredToBecomeImportant () 


// A simple dependency, which does not require other injected dependency,
// and is not required for others
class ThisIsUsefulButNotImportant : IThisIsUsefulButNotImportant

    public ThisIsUsefulButNotImportant () 


class Program

    private readonly WeaponOfChoiceInIoC container;

    public void ConfigureDependencies()
    
        container = new WeaponOfChoiceInIoC();

        container.Register(IThisIsRequiredToBecomeImportant,
            ThisIsRequiredToBecomeImportant);
        container.Register(IThisIsReallyImportant,
            ThisIsReallyImportant );
        container.Register(IThisIsUsefulButNotImportant,
            ThisIsUsefulButNotImportant );
    

    public void MethodToPlayWithDependencies()
    
        var toy = container.GetInstance(NeedSomeDependeciesToBeInjected);