Background Thread that uses ApplicaitonDBContext - asp.net-mvc

Question

I am trying to wire up a background thread that will update the database once an hour from Active Directory. I am not sure how to pass the current
public void ConfigureServices(IServiceCollection services)
{
services.Configure<CookiePolicyOptions>(options =>
{
// This lambda determines whether user consent for non-essential cookies is needed for a given request.
options.CheckConsentNeeded = context => false;
options.MinimumSameSitePolicy = SameSiteMode.None;
});
// Add framework services.
services.AddDbContext<ApplicationDbContext>(options =>
options.UseSqlServer(Configuration.GetConnectionString("Connection")));
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1).AddSessionStateTempDataProvider();
services.AddSession();
services.AddHttpContextAccessor();
services.AddSingleton(Configuration);
services.AddScoped<IAppDbRepository, AppDbRepository>();
services.AddScoped<IActiveDirectoryUtility, ActiveDirectoryUtility>();
services.AddScoped<IActiveDirectoryManager, ActiveDirectoryManager>();
services.AddHostedService<LdapManager>();
services.AddScoped<ILdapManager, LdapManager>();
}
In the LdapManager class I would like to call the UpdateUsers method every hour:
public class LdapManager : ILdapManager, IHostedService
{
private IConfiguration _configuration = null;
private Logging _logger;
private List<string> ldapConnectorForDirectoryEntries = new List<string>();
public LdapManager(IConfiguration configuration)
{
_configuration = configuration;
UpdateUsers();
SyncActiveDirectoryUsers();
}
public void SyncActiveDirectoryUsers()
{
try
{
using (var waitHandle = new AutoResetEvent(false))
{
ThreadPool.RegisterWaitForSingleObject(waitHandle, (state, timeout) => { UpdateUsers(); }, null, TimeSpan.FromHours(1), false);
}
}
catch
{
throw;
}
}
}
The UpdateUsers() method should be able to call the applicationDBContext.SaveChanges() method.
How can I ensure that the LDAP manger class can use the Application DB context?

Answer 1

You probably want class LdapManager : BackgroundService, ILdapManager
BackgroundService is .NET Core 2.1, there is a code sample available for core 2.0
Inject IServiceScopeFactory and override Task ExecuteAsync( ), run a while loop there.
while(!stoppingToken.IsCancellationRequested)
{
using (var scope = _serviceScopeFactory.CreateScope())
{
var context = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
...; // do your stuff
}
await Task.Delay(myConfig.BackgroundDelay, stoppingToken);
}
And here is a good read about this on MSDN, including the code sample for 2.0

Answer 2

For accessing ApplicationDbContext from HostedService.
DbHostedService
public class DbHostedService : IHostedService
{
private readonly ILogger _logger;
public DbHostedService(IServiceProvider services,
ILogger<DbHostedService> logger)
{
Services = services;
_logger = logger;
}
public IServiceProvider Services { get; }
public Task StartAsync(CancellationToken cancellationToken)
{
_logger.LogInformation("Consume Scoped Service Hosted Service is starting.");
DoWork();
return Task.CompletedTask;
}
private void DoWork()
{
_logger.LogInformation("Consume Scoped Service Hosted Service is working.");
using (var scope = Services.CreateScope())
{
var context = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
var user = context.Users.LastOrDefault();
_logger.LogInformation(user?.UserName);
}
}
public Task StopAsync(CancellationToken cancellationToken)
{
_logger.LogInformation("Consume Scoped Service Hosted Service is stopping.");
return Task.CompletedTask;
}
}
Register DbHostedService
services.AddHostedService<DbHostedService>();