BackgroundService with asp.net Core MVC 3.1 - asp.net-core-mvc

Question

Here is what i've done:
public void ConfigureServices(IServiceCollection services)
{
...
services.AddHostedService<MyBatch>();
}
public class MyBatch : BackgroundService
{
protected override async Task ExecuteAsync(CancellationToken stopToken)
{
while (!stopToken.IsCancellationRequested)
{
Console.Writeline("test");
await Task.Delay(TimeSpan.FromSeconds(10));
}
}
}
I have 2 problems:
First: The web application does not respond on 5000 port when i launch "dotnet run". If i remove my batch, the 5000 port works again. (test messages are displayed on console)
Second: I want to access to my database with Entity Framework. How can i access to my database context from this batch file ?
Thanks

Answer 1

I want to access to my database with Entity Framework. How can i access to my database context from this batch file ?
To consume a scoped service (such as DbContext etc) from singleton hosted service, you can create a scope then use it to resolve scoped service(s) you need from this scope, like below.
public class MyBatch : BackgroundService
{
public IServiceProvider Services { get; }
public MyBatch(IServiceProvider services)
{
Services = services;
}
protected override async Task ExecuteAsync(CancellationToken stopToken)
{
while (!stopToken.IsCancellationRequested)
{
Console.WriteLine("test");
await Task.Delay(TimeSpan.FromSeconds(10));
await DoWithDb(stopToken);
}
}
private async Task DoWithDb(CancellationToken stoppingToken)
{
//...
using (var scope = Services.CreateScope())
{
var _myDbContext =
scope.ServiceProvider
.GetRequiredService<MyDbContext>();
//code logic here
//...
}
}
}
You can also get detailed information about "consuming a scoped service in a background task" from here: https://learn.microsoft.com/en-us/aspnet/core/fundamentals/host/hosted-services?view=aspnetcore-3.1&tabs=visual-studio#consuming-a-scoped-service-in-a-background-task