Some services are not able to be constructed (Error while validating the service descriptor 'ServiceType: Microsoft.Extensions.Hosting.IHostedService Lifetime: Singleton ImplementationType: WindowServiceSample1.Worker': Cannot consume scoped service 'WindowServiceSample1.Data.ApplicationDbContext' from singleton 'Microsoft.Extensions.Hosting.IHostedService'.)

 using WindowServiceSample1;
using WindowServiceSample1.Data;
using Microsoft.EntityFrameworkCore;
 
IHost host = Host.CreateDefaultBuilder(args)
    .UseWindowsService(options =>
    {
        options.ServiceName = "Abc Service New";
    })
    .ConfigureServices(services =>
    {   
        services.AddHostedService<Worker>();
        services.AddDbContext<ApplicationDbContext>(options => options.UseSqlServer("Server=DESKTOP-4NUBQP8\\SQLEXPRESS;Database=MyDatabase;Trusted_Connection=True;"));

    })
    .Build();
    await host.RunAsync();

Worker class code -

namespace WindowServiceSample1
{
    public class Worker : BackgroundService
    {
        private readonly ILogger<Worker> _logger;
        private readonly ApplicationDbContext _db;

        public Worker(ILogger<Worker> logger, ApplicationDbContext db)
        {
            _logger = logger;
            _db = db;
        }

        protected override async Task ExecuteAsync(CancellationToken stoppingToken)
        {
            while (!stoppingToken.IsCancellationRequested)
            {

                Notification item = new Notification();
                item.EUID = "test";
                item.StoreNumber = "test";
                item.NotificationType = "test";
                item.Status = "test";

                _db.Notifications.Add(item);
                await _db.SaveChangesAsync();
                
                _logger.LogWarning("ABC Service running at: {time}", DateTimeOffset.Now);
                await Task.Delay(TimeSpan.FromSeconds(5), stoppingToken);
            }
        }
    }
}

Application DB Context class

namespace WindowServiceSample1.Data
{
    public class ApplicationDbContext : DbContext
    {
        public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : base(options)
        {
        }
 
        public DbSet<Notification> Notifications { get; set; }

    }
}

CodePudding user response：

As the error shows we should consume scope services in scoped instances to avoid data corruption or threading issue.

You should use Using ServiceScopeFactory to resolve scope instances.

Like this:

    public Worker(ILogger<Worker> logger, , IServiceScopeFactory factory )
    {
        _logger = logger;
        _db = factory.CreateScope().ServiceProvider.GetRequiredService<ApplicationDbContext>();
   }

    }