在.Net 6 Worker服务中使用appsettings.json

Question

Is I wanted to add a singleton service that is dependent on appsettings.

How would I do this in the.Net 6 worker service startup?

using AutoMapper;

var mapperConfig = new MapperConfiguration(mc =>
{
    mc.AddProfile(new MappingProfile());
});

IMapper mapper = mapperConfig.CreateMapper();

IHost host = Host.CreateDefaultBuilder(args)
    .ConfigureServices(services =>
    {
        services.AddHostedService<Worker>();
        services.AddSingleton(mapper);
        services.AddSingleton<IOrderNumberGenerator, OrderNumberGenerator>();

        services.AddSingleton(new ServiceIwantToCall(<--I need too use apsettings here-->));
    })
    .Build();

await host.RunAsync();

Answer 1

At the moment you're trying to register an instance of ServiceIwantToCall . You can instead register a factory method to resolve one, and once it's resolved it will be a singleton. For example, this anonymous method:

services.AddSingleton(serviceProvider => { 
    // resolve the configuration provider from the container
    IConfiguration config = serviceProvider.GetRequiredService<IConfiguration>();

    // get the config value and instantiate a ServiceIwantToCall
    // return the instantiated service
    string someValue = config["myValueKey"];
    return new ServiceIwantToCall(someValue);
});