I am using .NET 5 and I want to run a background task using IHostedService classess as you can see:

public class PasargadJobs : IHostedService, IDisposable
{
    private Timer _timer = null!;
    readonly  ITerminalService _terminalService;
    readonly  IMessageService _messageService;
    readonly IMerchantService _merchantService;
    
    public PasargadJobs(
        IMerchantService merchantService,
        ITerminalService terminalService,
        IMessageService messageService)
    {
        _messageService = messageService;
        _terminalService = terminalService;
        _merchantService = merchantService;
    }
    
    //other parts of code are removed for short code
}

So I have to inject it to service collection as you can see :

services.AddHostedService<PasargadJobs>();

But after adding this I got this error :

System.AggregateException: 'Some services are not able to be constructed (Error while validating the service descriptor 'ServiceType: Microsoft.Extensions.Hosting.IHostedService Lifetime: Singleton ImplementationType: MIMS.Portal.ScheduleJobs.PasargadJobs': Cannot consume scoped service 'Microsoft.EntityFrameworkCore.DbContextOptions`1[MIMS.Portal.Infrustructure.Repositories.AppDbContext]' from singleton 'Microsoft.Extensions.Hosting.IHostedService'.)'

Here is my startup.cs

services.AddExpressiveAnnotations();

//--- DB Context ---//
services.AddTransient<AppDbContext, AppDbContext>();
//--- Repositories ---//
services.AddTransient(typeof(IGenericRepository<>), typeof(GenericRepository<>));
services.AddTransient<IMerchantRepository, MerchantRepository>();
services.AddTransient<IBankAccountRepository, BankAccountRepository>();
services.AddTransient<IBankRepository, BankRepository>();
services.AddTransient<IGeoRepository, GeoRepository>();
services.AddTransient<IDepartmentRepository, DepartmentRepository>();
services.AddTransient<IDeviceRepository, DeviceRepository>();
services.AddTransient<IInvoiceRepository, InvoiceRepository>();
services.AddTransient<IStoreRepository, StoreRepository>();
services.AddTransient<ITerminalRepository, TerminalRepository>();
services.AddTransient<ITicketRepository, TicketRepository>();
services.AddTransient<IUserRepository, UserRepository>();
services.AddTransient<IFileRepository, FileRepository>();
services.AddTransient<IPartnerRepository, PartnerRepository>();
services.AddTransient<IStoreScopeRepository, StoreScopeRepository>();
services.AddTransient<ICommentRepository, CommentRepository>();
services.AddTransient<INewsRepository, NewsRepository>();
services.AddTransient<IPosBrandRepository, PosBrandRepository>();
//-- Services --//
services.AddTransient<IMerchantService, MerchantService>();
services.AddTransient<IBankAccountService, BankAccountService>();
services.AddTransient<IBankService, BankService>();
services.AddTransient<IGeoService, GeoService>();
services.AddTransient<IDepartmentService, DepartmentService>();
services.AddTransient<IDeviceService, DeviceService>();
services.AddTransient<IInvoiceService, InvoiceService>();
services.AddTransient<IStoreService, StoreService>();
services.AddTransient<ITerminalService, TerminalService>();
services.AddTransient<ITicketService, TicketService>();
services.AddTransient<IUsersService, UsersService>();
services.AddTransient<IFilesManagerService, FilesManagerService>();
services.AddTransient<IMessageService, MessageService>();
services.AddTransient<IPartnerService, PartnerService>();
services.AddTransient<IStoreScopeService, StoreScopeService>();
services.AddTransient<INewsService, NewsService>();
services.AddTransient<ICommentService, CommentService>();
services.AddTransient<IPosBrandService, PosBrandService>();

services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();

services
    .AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
    .AddJwtBearer(option =>
    {
        option.TokenValidationParameters = new TokenValidationParameters
        {
            ValidateIssuer = true,
            ValidateAudience = true,
            ValidateLifetime = true,
            ValidateIssuerSigningKey = true,
            ValidIssuer = "localhost",
            ValidAudience = "localhost",
            IssuerSigningKey = new SymmetricSecurityKey(
                Encoding.UTF8.GetBytes("wevhgfrtyhasdfghjklzxcvbnm"))
        };
    });
    
services.AddHostedService<PasargadJobs>();

CodePudding user response：

Your hosted service is singleton and you have an indirect dependency to a scoped service:

Cannot consume scoped service 'Microsoft.EntityFrameworkCore.DbContextOptions`1[MIMS.Portal.Infrustructure.Repositories.AppDbContext]' from singleton 'Microsoft.Extensions.Hosting.IHostedService'

You can workaround the problem in the following ways

Inject IServiceScopeFactory into your hosted service and create the service scope manually like below

using var scope = _serviceScopeFactory.CreateScope();
var service = scope.ServiceProvider.GetRequiredService<IScopedService>();

Do not put the CreateScope and GetRequiredService in the constructor of the hosted service: Since the hosted service is a singleton, the constructor will be called only once and hence instances created by scope.ServiceProvider.GetRequiredService<T>() will also be created once. So in this case you would use services that are designed to be short-lived as forever living singletons. Also do not forget to dispose scope after usage.

Since it looks like you are using Entity Framework Core and alternative to the approach above you could also consider to refactor your services to use IDbContextFactory<TContext> so they can be registered as singelton services.