Ian Chen

在開始前，先在appsetting.json定義了一個隨處可見的自訂設定

"MySetting": {
    "Id":123,
    "Name": "Test",
    "Data": ["A","B","C"]
  }

並且在Startup讀取配置

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();

            services.Configure<MyConfig>(Configuration.GetSection("MySetting"));
        }

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第一種，在讀取到配置時，就會拋出Exception

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();

            services.AddOptions<MyConfig>().Configure(config =>
            {
                Configuration.Bind(config);
            }).Validate(config => config.Id!=0,"Id 不能等於0");
        }

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第二種，為Config的屬性加上DataAnnotations的Attribute

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();

            services.AddOptions<MyConfig>().Configure(config =>
            {
                Configuration.Bind(config);
            }).ValidateDataAnnotations();
        }

    public class MyConfig
    {
        [Range(1, int.MaxValue)]
        public int Id { get; set; }

        public string Name { get; set; }

        public List<string> Data { get; set; }
    }

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第三種，實作一個IValidateOptions<T>

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();

            services.AddOptions<MyConfig>().Configure(config =>
            {
                Configuration.Bind(config);
            }).Services.AddTransient<IValidateOptions<MyConfig>, MyConfigValidate>();
        }

    public class MyConfigValidate : IValidateOptions<MyConfig>
    {
        public ValidateOptionsResult Validate(string name, MyConfig options)
        {
            if (options.Id == 0)
            {
                return ValidateOptionsResult.Fail("id can not be 0");
            }
            return ValidateOptionsResult.Success;
        }
    }

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Sample Code https://github.com/ianChen806/ConfigValidateSample