在ActionFilterAttribute中读取Asp.Net Core响应主体

Question

我正在使用 Asp.Net Core 作为 Rest Api 服务。我需要在 ActionFilter 中访问请求和响应。实际上，我在 OnActionExecuted 中找到了请求，但我无法读取响应结果。 我尝试按以下方式返回值：

[HttpGet]
[ProducesResponseType(typeof(ResponseType), (int)HttpStatusCode.OK)]
[Route("[action]")]
public async Task<IActionResult> Get(CancellationToken cancellationToken)
{
    var model = await _responseServices.Get(cancellationToken);
    return Ok(model);
}

在ActionFilter的OnExecuted方法中，如下所示：

_request = context.HttpContext.Request.ReadAsString().Result;
_response = context.HttpContext.Response.ReadAsString().Result; //?

我试图将以下代码作为扩展方法来获取ReadAsString的响应：

我试图将以下代码作为扩展方法来获取ReadAsString的响应：

public static async Task<string> ReadAsString(this HttpResponse response)
{
     var initialBody = response.Body;
     var buffer = new byte[Convert.ToInt32(response.ContentLength)];
     await response.Body.ReadAsync(buffer, 0, buffer.Length);
     var body = Encoding.UTF8.GetString(buffer);
     response.Body = initialBody;
     return body;
 }

但是，没有结果！

我如何在 OnActionExecuted 中获取响应？

感谢大家抽出时间尝试帮助解释。

- Saeid Mirzaei

---

你可以从 https://dev59.com/4WPVa4cB1Zd3GeqP9dVv 获取灵感。 - Khai Nguyen

谢谢，我尝试了很多方法，但所有的主题都没有得到响应的结果。 - Saeid Mirzaei

你为什么想要读取 Response？虽然通过读取响应可能可以实现，但如果您告诉我们您的意图，可能有更好的方法来实现您的目标。 - itminus

我需要知道向客户提供哪些数据，并将所有结果记录为JSON格式。@itminus - Saeid Mirzaei

@itminus 谢谢您抽出时间来尝试帮助。 - Saeid Mirzaei

Answer 1

如果您正在登录以获取JSON结果或查看结果，则无需读取整个响应流。只需对 context.Result 进行序列化：

public class MyFilterAttribute : ActionFilterAttribute
{
    private ILogger<MyFilterAttribute> logger;

    public MyFilterAttribute(ILogger<MyFilterAttribute> logger){
        this.logger = logger;
    }
    public override void OnActionExecuted(ActionExecutedContext context)
    {
        var result = context.Result;
        if (result is JsonResult json)
        {
            var x = json.Value;
            var status = json.StatusCode;
            this.logger.LogInformation(JsonConvert.SerializeObject(x));
        }
        if(result is ViewResult view){
            // I think it's better to log ViewData instead of the finally rendered template string
            var status = view.StatusCode;
            var x = view.ViewData;
            var name = view.ViewName;
            this.logger.LogInformation(JsonConvert.SerializeObject(x));
        }
        else{
            this.logger.LogInformation("...");
        }
    }

- itminus

---

这个答案在代码方面比我看到的其他常见解决方案要高效得多，这些解决方案似乎普遍建议替换和跟踪 Response.Body 的内存流！谢谢！ - Matsu Q.

在过滤器中，context.Result 始终为 null。 - undefined

Answer 2

我知道已经有一个答案了，但我想补充一下，问题在于MVC管道在运行ActionFilter时没有填充Response.Body，因此您无法访问它。 Response.Body由MVC middleware填充。

如果您想读取Response.Body，那么您需要创建自己的自定义middleware来拦截响应对象被填充的调用。有许多网站可以向您展示如何做到这一点。一个例子在这里。

正如其他答案中所讨论的那样，如果您想在ActionFilter中完成操作，则可以使用context.Result来访问信息。

- Simply Ged

Answer 3

如果您想在ASP.NET Core过滤器管道中记录整个请求和响应，可以使用结果过滤器属性。

    public class LogRequestResponseAttribute : TypeFilterAttribute
    {
        public LogRequestResponseAttribute() : base(typeof(LogRequestResponseImplementation)) { }

        private class LogRequestResponseImplementation : IAsyncResultFilter
        {
            public async Task OnResultExecutionAsync(ResultExecutingContext context, ResultExecutionDelegate next)
            {
                var requestHeadersText = CommonLoggingTools.SerializeHeaders(context.HttpContext.Request.Headers);
                Log.Information("requestHeaders: " + requestHeadersText);

                var requestBodyText = await CommonLoggingTools.FormatRequestBody(context.HttpContext.Request);
                Log.Information("requestBody: " + requestBodyText);

                await next();

                var responseHeadersText = CommonLoggingTools.SerializeHeaders(context.HttpContext.Response.Headers);
                Log.Information("responseHeaders: " + responseHeadersText);

                var responseBodyText = await CommonLoggingTools.FormatResponseBody(context.HttpContext.Response);
                Log.Information("responseBody: " + responseBodyText);
            }
        }
    }

在 Startup.cs 中添加。

    app.UseMiddleware<ResponseRewindMiddleware>();

    services.AddScoped<LogRequestResponseAttribute>();

在某处添加静态类

    public static class CommonLoggingTools
    {
        public static async Task<string> FormatRequestBody(HttpRequest request)
        {
            //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).ConfigureAwait(false);

            //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.Position = 0;

            return $"{request.Scheme} {request.Host}{request.Path} {request.QueryString} {bodyAsText}";
        }

        public static async Task<string> FormatResponseBody(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);

            response.Body.Position = 0;

            //Return the string for the response, including the status code (e.g. 200, 404, 401, etc.)
            return $"{response.StatusCode}: {text}";
        }

        public static string SerializeHeaders(IHeaderDictionary headers)
        {
            var dict = new Dictionary<string, string>();

            foreach (var item in headers.ToList())
            {
                //if (item.Value != null)
                //{
                var header = string.Empty;
                foreach (var value in item.Value)
                {
                    header += value + " ";
                }

                // Trim the trailing space and add item to the dictionary
                header = header.TrimEnd(" ".ToCharArray());
                dict.Add(item.Key, header);
                //}
            }

            return JsonConvert.SerializeObject(dict, Formatting.Indented);
        }
    }

    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;

            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;
            }

        } 

- Stefan Varga

Answer 4

你也可以做...

string response = "Hello";
if (result is ObjectResult objectResult)
        {
            var status = objectResult.StatusCode;
            var value = objectResult.Value;
            var stringResult = objectResult.ToString();
            responce = (JsonConvert.SerializeObject(value));
        }

我在一个 .net core 应用程序中使用了这个。

希望它有所帮助。

- Bukunmi