.NET Core 3 Worker 服务依赖注入配置通过 IOptions答案

【问题标题】：.NET Core 3 Worker Service Dependency Injection Configuration by IOptions.NET Core 3 Worker 服务依赖注入配置通过 IOptions
【发布时间】：2019-10-30 00:52:32
【问题描述】：

我有一个关于 Worker Service 上的 DI 的问题，该问题回答了下面的另一篇文章。

.NET Core 3 Worker Service Settings Dependency Injection

如果我想添加一些帮助类并注册如下。我如何使用该选项注入。因为我想，我错过了什么……

public static IHostBuilder CreateHostBuilder(string[] args)
    {
        return Host.CreateDefaultBuilder(args)

            .ConfigureAppConfiguration((hostContext, config) =>
            {
                // Configure the app here.
                config
                .SetBasePath(Environment.CurrentDirectory)
                .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
                .AddJsonFile($"appsettings.{hostContext.HostingEnvironment.EnvironmentName}.json", optional: true);

                config.AddEnvironmentVariables();

                Configuration = config.Build();

            })

            .ConfigureServices((hostContext, services) =>
            {

                services.AddOptions();               

                services.Configure<MySettings>(Configuration.GetSection("MySettings"));                    


                services.AddSingleton<RedisHelper>();

                services.AddHostedService<Worker>();                   

            });
    }

RedisHelper 类有一个像这样的构造函数作为 Worker。

public static MySettings _configuration { get; set; }

public RedisHelper(IOptions<MySettings> configuration)
{
    if (configuration != null)
        _configuration = configuration.Value;
}

【问题讨论】：

标签： c# dependency-injection .net-core backgroundworker

【解决方案1】：

无需自己构建配置。您可以通过 hostContext 在 ConfigureServices 中访问它

public static IHostBuilder CreateHostBuilder(string[] args) {
    return Host.CreateDefaultBuilder(args)
        .ConfigureAppConfiguration((hostContext, config) => {
            // Configure the app here.
            config
                .SetBasePath(Environment.CurrentDirectory)
                .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
                .AddJsonFile($"appsettings.{hostContext.HostingEnvironment.EnvironmentName}.json", optional: true);

            config.AddEnvironmentVariables();
        })
        .ConfigureServices((hostContext, services) => {

            services.AddOptions();               

            services.Configure<MySettings>(hostContext.Configuration.GetSection("MySettings"));
            services.AddSingleton<RedisHelper>();
            services.AddHostedService<Worker>(); 
        });
}

现在只需将选项注入所需的辅助类

//...

public RedisHelper(IOptions<MySettings> configuration) {
    if (configuration != null)
        _configuration = configuration.Value;
}

//...

和 Worker 服务

public Worker(RedisHelper helper) {
    this.helper = helper;
}

【讨论】：