状态码不成功时无法读取 HttpResponseMessage 内容

Question

我有一项服务使用 HttpClient:

使用 SMS REST API

HttpClient http = this._httpClientFactory.CreateClient();
// Skipped: setup HttpRequestMessage
using (HttpResponseMessage response = await http.SendAsync(request))
{
    try
    {
        _ = response.EnsureSuccessStatusCode();
    }
    catch (HttpRequestException)
    {
        string responseString = await response.Content.ReadAsStringAsync(); // Fails with ObjectDisposedException
        this._logger.LogInformation(
            "Received invalid HTTP response status '{0}' from SMS API. Response content was {1}.",
            (int)response.StatusCode,
            responseString
        );
        throw;
    }
}

API returns 一个错误，但我希望能够记录它。所以我需要记录失败状态代码（我可以从 response.StatusCode 中读取）和相关内容（可能包含其他错误有用的详细信息）。

此代码在指令 await response.Content.ReadAsStringAsync() 上失败，但出现以下异常：

System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'System.Net.Http.HttpConnection+HttpConnectionResponseContent'.
Module "System.Net.Http.HttpContent", in CheckDisposed
Module "System.Net.Http.HttpContent", in ReadAsStringAsync

一些消息来源建议当状态码不在成功范围 (200-299) 内时，您不应阅读响应内容，但如果响应确实包含有用的错误详细信息怎么办？

.NET 使用版本：AWS lambda linux 运行时上的 .NET Core 2.1.12。

Answer 1

好的，显然这是 .NET API 中的 a known issue，它已在 .NET Core 3.0 中得到解决。 response.EnsureSuccessStatusCode()实际上是在处理响应内容。它以这种方式实现，据说可以帮助用户：

// Disposing the content should help users: If users call EnsureSuccessStatusCode(), an exception is
// thrown if the response status code is != 2xx. I.e. the behavior is similar to a failed request (e.g.
// connection failure). Users don't expect to dispose the content in this case: If an exception is
// thrown, the object is responsible fore cleaning up its state.

这是一种不良行为，已从 3.0 中删除。与此同时，我只是在日志之前切换到使用IsSuccessStatusCode：

HttpClient http = this._httpClientFactory.CreateClient();
// Skipped: setup HttpRequestMessage
using (HttpResponseMessage response = await http.SendAsync(request))
{
    if (!response.IsSuccessStatusCode)
    {
        string responseString = await response.Content.ReadAsStringAsync(); // Fails with ObjectDisposedException
        this._logger.LogInformation(
            "Received invalid HTTP response status '{0}' from SMS API. Response content was {1}.",
            (int)response.StatusCode,
            responseString
        );
        _ = response.EnsureSuccessStatusCode();
    }
}

有点多余，但应该可以。

状态码不成功时无法读取 HttpResponseMessage 内容

Can't read HttpResponseMessage content when the status code is not success

c#

dotnet-httpclient

.net-core