.NET Core 5.0 - IServiceCollection.Configure 和 ILogger

Question

我有一个注册其服务的图书馆：

public static IServiceCollection AddViewStringRenderer(this IServiceCollection services, string contentRootPath, ILogger logger)
{
    services.Configure<RazorViewEngineOptions>(options => { options.ViewLocationExpanders.Add(new ViewLocationExpander(contentRootPath, logger)); });
    services.AddTransient<IRazorViewToStringRenderer, RazorViewToStringRenderer>();
    ...
    return services;
}

而且，如您所见，我需要services.Configure<RazorViewEngineOptions>(...)的记录器，因此它是此扩展方法的参数。

但是由于该方法用于Startup.ConfigureServices()我们没有办法在 .NET 5 中实例化ILogger 。如何将记录器传递给services.Configure() ？

Answer 1

好的，非常感谢 David Fowler 指出了这种模式 - Resolving services when using IOptions 。

结果如下：

public class RazorViewEngineConfigureOptions : IConfigureOptions<RazorViewEngineOptions>
{
    private readonly ILogger<ViewLocationExpander> _logger;
    private readonly string _contentRootPath;

    public RazorViewEngineConfigureOptions(IHostEnvironment env, ILogger<ViewLocationExpander> logger)
    {
        _contentRootPath = env.ContentRootPath;
        _logger = logger;
    }

    public void Configure(RazorViewEngineOptions options)
    {
       options.ViewLocationExpanders.Add(new ViewLocationExpander(_contentRootPath, _logger));
    }
}

public static class RegisterServices
{
    public static IServiceCollection AddEmailerService(this IServiceCollection services)
    {
        services.AddSingleton<IConfigureOptions<RazorViewEngineOptions>, RazorViewEngineConfigureOptions>();
        services.AddTransient<IRazorViewToStringRenderer, RazorViewToStringRenderer>();

        ...
        return services;
    }
}