在.Net 6 Worker服務中使用appsettings.json

Question

我想添加一個依賴於 appsettings 的 singleton 服務嗎？

我將如何在 .Net 6 worker 服務啟動中執行此操作？

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

目前您正在嘗試注冊ServiceIwantToCall的實例。 您可以改為注冊一個工廠方法來解析一個，一旦它被解析，它將是一個 singleton。例如，這個匿名方法：

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);
});