仅当内容类型等于 json 时才记录 WebAPI答案

【问题标题】：WebAPI log only when content type equal to json仅当内容类型等于 json 时才记录 WebAPI
【发布时间】：2018-10-18 15:07:51
【问题描述】：

目前，我有一个全局注册的处理程序来捕获各种请求和响应。然而，系统包含一些端点，其内容类型为 pdf 或 csv。

   public class LogRequestAndResponseHandler : DelegatingHandler
    {
        protected override async Task<HttpResponseMessage> SendAsync(
            HttpRequestMessage request, CancellationToken cancellationToken)
        {
            // log request body
            var requestBody = await request.Content.ReadAsStringAsync();

            LogUtil.Info("[" + request.GetCorrelationId() + "] Call:" + request.RequestUri,"httpTrace");
            if(!string.IsNullOrEmpty(requestBody))
            LogUtil.Info(requestBody,"httpTrace");

            // let other handlers process the request
            var result = await base.SendAsync(request, cancellationToken);

            if (result.Content != null)
            {

                // once response body is ready, log it
                var responseBody = await result.Content.ReadAsStringAsync();
                //LogUtil.Info(responseBody,"httpTrace");
                LogUtil.Info("[" + request.GetCorrelationId().ToString() + "] Return:" + responseBody,"httpTrace");
            }

            return result;
        }
    }

我正在使用上面的代码，每当调用 pdf 端点时，整个 pdf 正文将被捕获到二进制格式的日志中。

我想知道仅过滤 json 正文或标头进行记录的最佳方法是什么。

【问题讨论】：

标签： c# asp.net-web-api2 nlog

【解决方案1】：

客户端和服务器都应该使用Content-Type 标头来指示正文的内容类型。

您可以同时检查请求和响应 - 可能是这样的：

public class LogRequestAndResponseHandler : DelegatingHandler
{

    private bool ShouldLog(IDictionary<string, IEnumerable<string>> headers)
    {
        if (headers.TryGetValue("Content-Type", out IEnumerable<string> values))
        {
            if (values.Any(x => x == "application/json"))
                return true;
        }

        return false;
    }


    protected override async Task<HttpResponseMessage> SendAsync(
        HttpRequestMessage request, CancellationToken cancellationToken)
    {
        // log request body

        if (ShouldLog(request.Headers.ToDictionary(x => x.Key, x => x.Value)))
        {
            var requestBody = await request.Content.ReadAsStringAsync();
            LogUtil.Info("[" + request.GetCorrelationId() + "] Call:" + request.RequestUri, "httpTrace");
            if (!string.IsNullOrEmpty(requestBody))
                LogUtil.Info(requestBody, "httpTrace");
        }


        // let other handlers process the request
        var result = await base.SendAsync(request, cancellationToken);

        if (result.Content != null)
        {
            if (ShouldLog(result.Headers.ToDictionary(x => x.Key, x => x.Value)))
            {
                // once response body is ready, log it
                var responseBody = await result.Content.ReadAsStringAsync();
                //LogUtil.Info(responseBody,"httpTrace");
                LogUtil.Info("[" + request.GetCorrelationId().ToString() + "] Return:" + responseBody, "httpTrace");
            }
        }

        return result;
    }

}

您可能需要进一步完善它，也许您还想记录text/plain 或其他一些类型，但这应该可以帮助您入门。

【讨论】：