.netcore2.1 統一介面返回屬性名稱

　　為了開發規範，有時需要統一響應屬性名稱，.netcore已為我們封裝好了，我們直接用即可。

　　在StartUp類中ConfigureServices方法中，添加如下代碼：

 public void ConfigureServices(IServiceCollection services)
        {
          
            services.AddMvc()
            .AddJsonOptions(opt =>
            {
                // opt.SerializerSettings.ContractResolver = new Newtonsoft.Json.Serialization.DefaultContractResolver();//原樣輸出，後臺屬性怎麼寫的，返回的 json 就是怎樣的

               // opt.SerializerSettings.ContractResolver = new Newtonsoft.Json.Serialization.CamelCasePropertyNamesContractResolver();//駝峰命名法，首字母小寫

                opt.SerializerSettings.ContractResolver =new LowercaseContractResolver();//自定義擴展，屬性全為小寫
            })
            .SetCompatibilityVersion(CompatibilityVersion.Version_2_1);

　　自定義全部小寫擴展類：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace MyApi.Common.Extension
{
    public class LowercaseContractResolver: Newtonsoft.Json.Serialization.DefaultContractResolver
    {
        protected override string ResolvePropertyName(string propertyName)
        {
            return propertyName.ToLower();
        }
    }
}