c# - 状态码不成功时无法读取HttpResponseMessage内容

Question

我有一项服务正在使用 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 返回错误，但我希望能够记录它。因此，我需要记录失败的状态代码(我可以从 response.StatusCode 中读取)和关联的内容(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，当状态代码不在成功范围 (200-299) 内时，您不应该读取响应内容，但是如果响应确实包含有用的错误详细信息怎么办？

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

Answer 1

好的，显然这是 a known issue在 .NET API 中，该问题已在 .NET Core 3.0 中得到解决。 response.EnsureSuccessStatusCode() 实际上是在处理响应内容。它的实现方式据说是为了帮助用户:

// 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。