读取RequestBody会破坏ASP.NET Core 2.2网关中的流

Question

我有一个中间件来跟踪我在ASP.NET Core 2.2 API中自定义开发的网关的性能。我已经使用了StackOverflow的this post。

主要部分如下：

public class ResponseRewindMiddleware {
    private readonly RequestDelegate next;

    public ResponseRewindMiddleware(RequestDelegate next) {
        this.next = next;
    }

    public async Task Invoke(HttpContext context) {

        Stream originalBody = context.Response.Body;
        /* MY CODE COMES HERE */

        try {
            using (var memStream = new MemoryStream()) {
                context.Response.Body = memStream;

                await next(context);

                memStream.Position = 0;
                string responseBody = new StreamReader(memStream).ReadToEnd();

                memStream.Position = 0;
                await memStream.CopyToAsync(originalBody);
            }

        } finally {
            context.Response.Body = originalBody;
        }

    } 

此代码运行正常。但是我想将输入（JSON主体）记录到网关，然后添加以下几行：

using (System.IO.StreamReader rd = new System.IO.StreamReader(context.Request.Body))
{
    bodyStr = rd.ReadToEnd();
}

这将从Request中读取输入正文，但流程中断，其余流程未完成，从而导致“ HTTP 500 Internal Server Error”。我假设通过Stream读取Request正文有问题。

如何在不中断流程的情况下阅读请求正文？

Answer 1

想法是调用EnableBuffering以启用多次读取，然后在完成读取请求后不处理请求正文。以下对我有用。

// Enable the request body to be read in the future
context.Request.EnableBuffering();

// Read the request body, but do not dispose it
var stream = new StreamReader(context.Request.Body);            
string requestBody = await stream.ReadToEndAsync();

// Reset to the origin so the next read would start from the beginning
context.Request.Body.Seek(0, SeekOrigin.Begin);