ASP.NET Core：JSON配置GetSection返回null

Question

我有一个文件appsettings.json，看起来像这样：

{
    "MyConfig": {
        "ConfigA": "value",
        "ConfigB": "value"
    }
}

在我的Startup.cs我正在建立我的IConfiguration：

public ConfigurationRoot Configuration { get; set; }

public Startup(ILoggerFactory loggerFactory, IHostingEnvironment environment)
{
      var builder = new ConfigurationBuilder()
                     .SetBasePath(environment.ContentRootPath)
                     .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)                             
                     .AddEnvironmentVariables();

      Configuration = builder.Build();
}

public void ConfigureServices(IServiceCollection services)
{
      //GetSection returns null...
      services.Configure<MyConfig>(Configuration.GetSection("MyConfig"));
}

但Configuration.GetSection("MyConfig")总是返回null，虽然该值存在于我的JSON文件中。 Configuration.GetSection("MyConfig:ConfigA")工作得很好。

我究竟做错了什么？

Answer 1

请参考下面的代码

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        var config = Configuration.GetSection("MyConfig");
        // To get the value configA
        var value = config["ConfigA"];

        // or direct get the value
        var configA = Configuration.GetSection("MyConfig:ConfigA");

        var myConfig = new MyConfig();
        // This is to bind to your object
        Configuration.GetSection("MyConfig").Bind(myConfig);
        var value2 = myConfig.ConfigA;
    }
}

Answer 2

这对我有用。

public void ConfigureServices(IServiceCollection services)  
{  
     services.Configure<MyConfig>(con=> Configuration.GetSection("MyConfig").Bind(con));  
}

Answer 3

我刚碰到这个。如果您使用完整路径，那么值就在那里，但我需要将它们自动绑定到配置类。

我将自动属性访问器添加到我的类的属性后，.Bind（config）开始工作。即

public class MyAppConfig {
  public string MyConfigProperty { get; set;} //this works
  public string MyConfigProperty2; //this does not work
}

Answer 4

对于发生这种情况并试图在测试项目中做同样事情的人来说，这对我有用：

other = config.GetSection("OtherSettings").Get<OtherSettings>();