如何包装 Web API 响应(在 .net 核心中)以保持一致性?

问题描述

我需要返回一个一致的响应，所有请求都返回一个类似的结构.在之前的 .NET web api 中，我可以使用 DelegatingHandler (MessageHandlers) 来实现这一点.我要返回的对象将被封装在 Result 元素中.所以基本上json响应会是这样的结构:

I need to return a consistent response with a similar structure returned for all requests. In the previous .NET web api, I was able to achieve this using DelegatingHandler (MessageHandlers). The object that I want to return will be encapsulated in the Result element. So basically the json response will be in this kind of structure:

示例 1:

{
    "RequestId":"some-guid-abcd-1234",
    "StatusCode":200,
    "Result":
    {
        "Id":42,
        "Todo":"Do Hello World"
    }
}

示例 2:

{
    "RequestId":"some-guid-abcd-1235",
    "StatusCode":200,
    "Result":
    {
        [
            {        
                "Id":42,
                "Todo":"Print Hello World"
            },
            {        
                "Id":43,
                "Todo":"Print Thank you"
            }           
        ]

    }
}

在 .NET 核心中，看起来我需要通过中间件来执行此操作.我试过了，但是当您可以调用 HttpResponseMessage.TryGetContentValue 来获取内容并将其包装在全局/通用响应模型中时，我没有看到更好的方法来提取内容，就像在以前的 Web API 中那样.

In .NET core, it looks like I need to do this via middleware. I tried but I don't see a nicer way to extract the content like how in the previous web API when you can call HttpResponseMessage.TryGetContentValue to get the content and wrap it in global/common response model.

如何在 .NET core 中实现同样的功能?

How can I achieve the same in .NET core?

推荐答案

我创建了一个中间件来包装响应以保持一致性.为了方便注册这个中间件，我还为 IApplicationBuilder 创建了一个扩展方法.所以在 Startup.cs 中，注册中间件:

I created a middleware to wrap the response for consistency. I also created an extension method to IApplicationBuilder for convenience when registering this middleware. So in Startup.cs, register middleware :

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    //code removed for brevity.
    ...
    app.UseResponseWrapper();

    //code removed for brevity.
    ...
}

这是中间件代码:

using System;
using System.IO;
using System.Net;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Newtonsoft.Json;

namespace RegistrationWeb.Middleware
{
    public class ResponseWrapper
    {
        private readonly RequestDelegate _next;

        public ResponseWrapper(RequestDelegate next)
        {
            _next = next;
        }

        public async Task Invoke(HttpContext context)
        {
            var currentBody = context.Response.Body;

            using (var memoryStream = new MemoryStream())
            {
                //set the current response to the memorystream.
                context.Response.Body = memoryStream;

                await _next(context);

                //reset the body 
                context.Response.Body = currentBody;
                memoryStream.Seek(0, SeekOrigin.Begin);

                var readToEnd = new StreamReader(memoryStream).ReadToEnd();
                var objResult = JsonConvert.DeserializeObject(readToEnd);
                var result = CommonApiResponse.Create((HttpStatusCode)context.Response.StatusCode, objResult, null);
                await context.Response.WriteAsync(JsonConvert.SerializeObject(result));
            }
        }

    }

    public static class ResponseWrapperExtensions
    {
        public static IApplicationBuilder UseResponseWrapper(this IApplicationBuilder builder)
        {
            return builder.UseMiddleware<ResponseWrapper>();
        }
    }


    public class CommonApiResponse
    {
        public static CommonApiResponse Create(HttpStatusCode statusCode, object result = null, string errorMessage = null)
        {
            return new CommonApiResponse(statusCode, result, errorMessage);
        }

        public string Version => "1.2.3";

        public int StatusCode { get; set; }
        public string RequestId { get; }

        public string ErrorMessage { get; set; }

        public object Result { get; set; }

        protected CommonApiResponse(HttpStatusCode statusCode, object result = null, string errorMessage = null)
        {
            RequestId = Guid.NewGuid().ToString();
            StatusCode = (int)statusCode;
            Result = result;
            ErrorMessage = errorMessage;
        }
    }
}

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