c# - 在 .Net Core AppSettings/配置中处理带句点的键名

Question

考虑关注 appsettings.json :

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*",

  "NumberOfRetries": 5,
  "Option1": "abc",
  "Option2":  "def"

}

为了阅读 NumberOfRetries以下类可以成功使用:

public class AppSettings
{
    public int NumberOfRetries { get; set; }
    public string Option1 { get; set; }
    public string Option2 { get; set; }
}

在 Startup.cs 中使用以下代码:

    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)
    {
        services.AddControllers();

        services.AddOptions();

        services.Configure<AppSettings>(Configuration);
    }

现在，假设 key 名称是 Number.Of.Retries而不是 NumberOfRetries - 中间有句号。

怎么会 AppSetings类(或方法本身)被修改以支持它？不能在属性名称中准确放置句点。

Answer 1

我明白你的意思，我快速查了一下，有能力提供关于如何配置你的选项的自定义逻辑。我做了一个快速原型(prototype)...

void Main()
{
    string json = @"{
      ""Logging"": {    
        ""LogLevel"": {
        ""Default"": ""Information"",
          ""Microsoft"": ""Warning"",
          ""Microsoft.Hosting.Lifetime"": ""Information""

        }
      },
      ""AllowedHosts"": ""*"",
      ""Number.Of.Retries"":  5
    }";

    using (var doc = System.Text.Json.JsonDocument.Parse(json, new JsonDocumentOptions {  AllowTrailingCommas = true, CommentHandling = JsonCommentHandling.Skip } ))
    {
        using(var stream = new MemoryStream())
        {
            using (var writer = new Utf8JsonWriter(stream))
            {
                doc.WriteTo(writer);
                writer.Flush();
            }       

            stream.Position = 0;

            // Usable code here
            IConfigurationRoot configuration = new ConfigurationBuilder().AddJsonStream(stream).Build();

            var services = new ServiceCollection();

            services.AddOptions<AppSettings>();

            // There is an option to configure it manually here, if it does not fit the convention
            services.Configure<AppSettings>((options) =>
            {
                options.NumberOfRetries = configuration.GetValue<int>("Number.Of.Retries");
            });

            var container = services.BuildServiceProvider();

            using (var scope = container.CreateScope())
            {
                var appSettings = scope.ServiceProvider.GetRequiredService<IOptions<AppSettings>>();

                Console.WriteLine(appSettings.Value.NumberOfRetries);
            }
        }
    }
}

public class AppSettings
{
    public int NumberOfRetries { get; set; }
}  

如果您有特定的设置模式，您可以为自己的“约定”创建自定义设置绑定(bind)器，我提供了一个非常基本的示例，它处理 '.'在设置中。

void Main()
{
    string json = @"{
      ""Logging"": {    
        ""LogLevel"": {
        ""Default"": ""Information"",
          ""Microsoft"": ""Warning"",
          ""Microsoft.Hosting.Lifetime"": ""Information""

        }
      },
      ""AllowedHosts"": ""*"",
      ""Number.Of.Retries"":  5
    }";

    using (var doc = System.Text.Json.JsonDocument.Parse(json, new JsonDocumentOptions {  AllowTrailingCommas = true, CommentHandling = JsonCommentHandling.Skip } ))
    {
        using(var stream = new MemoryStream())
        {
            using (var writer = new Utf8JsonWriter(stream))
            {
                doc.WriteTo(writer);
                writer.Flush();
            }       

            stream.Position = 0;

            // Usable code here
            IConfigurationRoot configuration = new ConfigurationBuilder().AddJsonStream(stream).Build();

            var services = new ServiceCollection();
            services.AddOptions<AppSettings>(); 
            services.AddSingleton<IConfiguration>(configuration);
            services.ConfigureOptions<CustomConfigureOptions>();

            var container = services.BuildServiceProvider();

            using (var scope = container.CreateScope())
            {
                var appSettings = scope.ServiceProvider.GetRequiredService<IOptions<AppSettings>>();

                Console.WriteLine(appSettings);
            }
        }
    }
}

public class AppSettings
{
    public int NumberOfRetries { get; set; }
}

public class CustomConfigureOptions : IConfigureOptions<AppSettings>
{
    private readonly IConfiguration configuration; 

    public CustomConfigureOptions(IConfiguration configuration)
    {
        this.configuration = configuration;
    }

    public void Configure(AppSettings options)
    {
        foreach(var pair in configuration.AsEnumerable())
        {
            foreach(var property in typeof(AppSettings).GetProperties())
            {
                if (property.Name.Equals(pair.Key.Replace(".", "")))
                {
                    property.SetValue(options, configuration.GetValue(property.PropertyType, pair.Key));
                }
            }
        }
    }
}