Coemgen4 Coemgen4 - 1 month ago 16
C# Question

System.InvalidOperationException: Unable to resolve service for type

I'm working on a Web API with ASP.NET Core. When I'm executing my API with a post request, an exception is throwing before my break point in the Post method of UnitController.

Exception


Request starting HTTP/1.1 POST http://localhost:5000/api/unit
application/json 31 fail: Microsoft.AspNetCore.Server.Kestrel[13]
Connection id "0HKVTL9A1LTD4": An unhandled exception was thrown by the application. System.InvalidOperationException: Unable to resolve service for type 'Project.DataAccess.Repository.UnitRepository' while attempting to activate 'Project.Service.UnitService'.


Context

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)
{
}
}
}


Version

"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-*"
},


Question

I think the problem is maybe with the inheritance between BaseRepository and IBaseRepository. But I don't understand where could be my mistake.
How can I correct this bug ?

Thank you for your helps :),

Answer

You're registering UnitRepository as IUnitRepository, but requesting your IoC resolve UnitRepository. It doesn't have a registration for that, so it's failing.

Try making UnitService take an IUnitRepository instead of a UnitRepository, that should resolve things (pardon the pun).

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