仅当内容类型等于 json 时才记录 WebAPI

Question

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。但是，系统包含一些内容类型为 pdf 或 csv 的端点。

   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 body 将以二进制格式捕获到日志中。

我想知道最好的过滤方法是什么只过滤jsonbody或header来记录。

Answer 1

客户端和服务器都应该使用Content-Type header来表示body的内容类型。

您可以检查请求和响应 - 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。

仅当内容类型等于 json 时才记录 WebAPI

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c#

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asp.net-web-api2