asp net core: Global Timer

Question

I would like to create a global timer which will check some data in the database, for example, once an hour.

So far, I have done this in the Startup.cs file:

    public Startup(IConfiguration configuration)
    {
        Start_GlobalTimer(3600000);
    }


        private void Start_GlobalTimer(double inInterval)
        {
            var t = new System.Timers.Timer();

            t.Elapsed += new ElapsedEventHandler(GlobalTimerWorker);

           t.Interval = inInterval;
           t.AutoReset = true;
           t.Enabled = true;
            t.Start();
        }

        private void GlobalTimerWorker()
        {
             // Here I need access into DBContext and UserManager
        }

My DB context looks like this.

    public class ApplicationDbContext : IdentityDbContext<AppUser>
    {
        public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options, IHttpContextAccessor inHttpContextAccessor) :
            base(options)
        {
            m_Options = options;
            m_HttpContextAccessor = inHttpContextAccessor;
        }
......
.....
    }

    public class AppUser : Microsoft.AspNetCore.Identity.IdentityUser
    {
        //--- Members ---
        .........
     }

The Timer works well, but I don't know how to make available ApplicationDbContext and UserManager in timer handler.
I need access to ApplicationDbContext and UserManager in ElapsedEventHandler of Timer.

I am a beginner in asp net core and I need advice. Thank so much.

Answer 1

Hi @jurin otruba ,

You could refer the following sample to create a BackgroundService, then in the BackgroundService, you can access the ApplicationDbContext and UserManager via the IServiceProvider. Code like this:

using Core5WebApplication.Data; //ApplicationDbContext  
using Microsoft.AspNetCore.Identity;  
using Microsoft.EntityFrameworkCore;  
using Microsoft.Extensions.DependencyInjection;  
using Microsoft.Extensions.Hosting;  
using Microsoft.Extensions.Logging;  
using System;  
using System.Linq;  
using System.Threading;  
using System.Threading.Tasks;  
  
namespace Core5WebApplication.Services  
{  
    public class TimedHostedService : IHostedService, IDisposable  
    {  
        private int executionCount = 0;  
        private readonly ILogger<TimedHostedService> _logger;  
        private Timer _timer = null!;  
  
        private readonly IServiceProvider _serviceProvider;  
        public TimedHostedService(ILogger<TimedHostedService> logger, IServiceProvider serviceProvider)  
        {  
            _logger = logger;  
            _serviceProvider = serviceProvider;  
        }  
  
        public Task StartAsync(CancellationToken stoppingToken)  
        {  
            _logger.LogInformation("Timed Hosted Service running.");  
  
            _timer = new Timer(DoWork, null, TimeSpan.FromSeconds(10),  
                TimeSpan.FromSeconds(10));  
  
            return Task.CompletedTask;  
        }  
  
        private void DoWork(object? state)  
        {  
            var count = Interlocked.Increment(ref executionCount);  
  
            //using ApplicationDbContext.  
            using (IServiceScope scope = _serviceProvider.CreateScope())  
            {  
                ApplicationDbContext  _context = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>();  
  
                _logger.LogInformation("First User Name (DBContext): {name}", _context.Users.OrderBy(c=>c.Id).FirstOrDefaultAsync().Result.UserName);   
            }  
            //using UserManger  
            using (IServiceScope scope = _serviceProvider.CreateScope())  
            {  
                UserManager<IdentityUser> _usermanager = scope.ServiceProvider.GetRequiredService<UserManager<IdentityUser>>();  
  
                _logger.LogInformation("First User Name (UserManger): {name}", _usermanager.FindByEmailAsync("aa@hotmail.com").Result?.UserName);  
            }  
            _logger.LogInformation(  
                "Timed Hosted Service is working. {currentdate} Count: {Count}", DateTime.Now.ToString() ,count);  
        }  
  
        public Task StopAsync(CancellationToken stoppingToken)  
        {  
            _logger.LogInformation("Timed Hosted Service is stopping.");  
  
            _timer?.Change(Timeout.Infinite, 0);  
  
            return Task.CompletedTask;  
        }  
  
        public void Dispose()  
        {  
            _timer?.Dispose();  
        }  
    }  
}  

Then, register the host service in the Startup.cs file:

        services.AddHostedService<TimedHostedService>();  

After running the application, the result is like this:

---

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Best regards,
Dillion

Answer 2

See the Hosted Services documentation which has timer and scoped service (for the DB access) examples.

Background tasks with hosted services in ASP.NET Core

Answer 3

Thanks a lot, I will try

Answer 4

Thank you very much, I already understand how it works