如何正确记录requestMessage.Content的实际请求内容？

问题原因 #

StringContent.ToString() 默认返回的是类型名称（即System.Net.Http.StringContent），而非实际的请求内容，因此日志无法显示具体的JSON数据。

方案一：直接使用已序列化的变量（推荐） #

你已经提前将请求对象序列化为requestJson变量，直接将该变量写入日志即可，无需从requestMessage.Content读取：

using var requestMessage = CreateRequest(authenticationResponse, HttpMethod.Post, uri);
var requestJson = JsonConvert.SerializeObject(request, _serializerSettings);
requestMessage.Content = new StringContent(requestJson, Encoding.UTF8, "application/json");
// 直接使用已序列化的requestJson记录日志
_logger.LogInformation($"[{nameof(PerformApiSearchQueryAsync)}] RequestContent='{requestJson}'");
// 执行API搜索
using var response = await _client.SendAsync(requestMessage);
_logger.LogInformation($"[{nameof(PerformApiSearchQueryAsync)}] Api responded with '{response.StatusCode}'. accesstoken='{authenticationResponse.AccessToken.Sanitize()}'");

方案二：从StringContent中读取内容（需处理流重置） #

如果必须从requestMessage.Content读取内容，需调用ReadAsStringAsync()方法，但要注意HTTP内容流默认仅能读取一次，读取后需重置流位置才能保证请求正常发送：

using var requestMessage = CreateRequest(authenticationResponse, HttpMethod.Post, uri);
var requestJson = JsonConvert.SerializeObject(request, _serializerSettings);
requestMessage.Content = new StringContent(requestJson, Encoding.UTF8, "application/json");

// 读取内容并记录日志
var contentString = await requestMessage.Content.ReadAsStringAsync();
_logger.LogInformation($"[{nameof(PerformApiSearchQueryAsync)}] RequestContent='{contentString}'");

// 重置内容流，确保SendAsync能正常读取
var byteContent = await requestMessage.Content.ReadAsByteArrayAsync();
requestMessage.Content = new ByteArrayContent(byteContent);
requestMessage.Content.Headers.ContentType = new MediaTypeHeaderValue("application/json");

// 执行API搜索
using var response = await _client.SendAsync(requestMessage);
_logger.LogInformation($"[{nameof(PerformApiSearchQueryAsync)}] Api responded with '{response.StatusCode}'. accesstoken='{authenticationResponse.AccessToken.Sanitize()}'");

内容的提问来源于stack exchange，提问作者wdtj