为请求日志记录添加自定义中间件时，模型绑定停止工作

Question

我正在使用以下类来记录对我的API的所有请求和响应。代码取自链接 https://exceptionnotfound.net/using-middleware-to-log-requests-and-responses-in-asp-net-core/。问题是当我注册这个中间件时，我的模型绑定停止工作。请求始终为空。我认为问题出在方法"FormatRequest"上，如果我删除对该方法的调用，它就会开始工作，但无法弄清楚为什么它会破坏模型绑定过程。

public class RequestResponseLoggingMiddleware
{
private readonly RequestDelegate _next;
public RequestResponseLoggingMiddleware(RequestDelegate next)
{
_next = next;
}
public async Task Invoke(HttpContext context)
{
//First, get the incoming request
var request = await FormatRequest(context.Request);
//Copy a pointer to the original response body stream
var originalBodyStream = context.Response.Body;
//Create a new memory stream...
using (var responseBody = new MemoryStream())
{
//...and use that for the temporary response body
context.Response.Body = responseBody;
//Continue down the Middleware pipeline, eventually returning to this class
await _next(context);
//Format the response from the server
var response = await FormatResponse(context.Response);
//TODO: Save log to chosen datastore
//Copy the contents of the new memory stream (which contains the response) to the original stream, which is then returned to the client.
await responseBody.CopyToAsync(originalBodyStream);
}
}
private async Task<string> FormatRequest(HttpRequest request)
{
var body = request.Body;
//This line allows us to set the reader for the request back at the beginning of its stream.
request.EnableRewind();
//We now need to read the request stream.  First, we create a new byte[] with the same length as the request stream...
var buffer = new byte[Convert.ToInt32(request.ContentLength)];
//...Then we copy the entire request stream into the new buffer.
await request.Body.ReadAsync(buffer, 0, buffer.Length);
//We convert the byte[] into a string using UTF8 encoding...
var bodyAsText = Encoding.UTF8.GetString(buffer);
//..and finally, assign the read body back to the request body, which is allowed because of EnableRewind()
request.Body = body;
return $"{request.Scheme} {request.Host}{request.Path} {request.QueryString} {bodyAsText}";
}
private async Task<string> FormatResponse(HttpResponse response)
{
//We need to read the response stream from the beginning...
response.Body.Seek(0, SeekOrigin.Begin);
//...and copy it into a string
string text = await new StreamReader(response.Body).ReadToEndAsync();
//We need to reset the reader for the response so that the client can read it.
response.Body.Seek(0, SeekOrigin.Begin);
//Return the string for the response, including the status code (e.g. 200, 404, 401, etc.)
return $"{response.StatusCode}: {text}";
}
}

这就是我注册它的方式，

public class Startup
{
//...
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
//Add our new middleware to the pipeline
app.UseMiddleware<RequestResponseLoggingMiddleware>();
app.UseMvc();
}
}

Answer 1

对于此问题，您可以尝试request.Body.Seek(0, SeekOrigin.Begin);重置正文而不是request.Body = body;

private async Task<string> FormatRequest(HttpRequest request)
{
var body = request.Body;
//This line allows us to set the reader for the request back at the beginning of its stream.
request.EnableRewind();
//We now need to read the request stream.  First, we create a new byte[] with the same length as the request stream...
var buffer = new byte[Convert.ToInt32(request.ContentLength)];
//...Then we copy the entire request stream into the new buffer.
await request.Body.ReadAsync(buffer, 0, buffer.Length);
//We convert the byte[] into a string using UTF8 encoding...
var bodyAsText = Encoding.UTF8.GetString(buffer);
//..and finally, assign the read body back to the request body, which is allowed because of EnableRewind()
//request.Body = body;
request.Body.Seek(0, SeekOrigin.Begin);
return $"{request.Scheme} {request.Host}{request.Path} {request.QueryString} {bodyAsText}";
}