Question

我的组织运行一个新闻网站，要求Facebook通过我们的发布流程抓取我们的内容。此请求通过一批请求发送到图API。批处理包含每个已发布文章的URL以及设置为POST的HTTP方法。

请求似乎总是返回200 OK，但内容并不总是被Facebook正确删除。这是用户点击我们应用程序前端文章的共享按钮的证据。 Facebook共享对话框显示过时或默认值。正确的值应反映我们的Open Graph元标记。

唯一能够可靠地解决这个问题的方法是使用Facebook共享调试器来重新扫描每次似乎都有效的内容。

Facebook的开发人员提出问题出在我们的实施中，如下所示：

private static async Task RefreshFacebookCacheAsync(IList<string> newsReleaseUris, CancellationToken token)
        {
            string appId = "our-app-id";
            string appSecret = "our-app-secret";

            bool newsSiteIsNotAccessibleFromFacebook = string.IsNullOrEmpty(appId) || string.IsNullOrEmpty(appSecret);
            if (newsSiteIsNotAccessibleFromFacebook)
            {
                // removed for brevity...
            }

            string graphUrl = "https://graph.facebook.com/?access_token" + $"{appId}|{appSecret}";

            HttpResponseMessage response = null;
            try
            {
                // set the accept type and create the batch operations
                client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
                var requests = newsReleaseUris.Select(u => new { method = "POST", relative_url = $"?id={u}&scrape=true" }).ToList();
                var serializedRequests = JsonConvert.SerializeObject(requests);

                // encode the batch operations
                var queryParams = new Dictionary<string, string>
                {
                    { "batch", serializedRequests }
                };

                // send the request and wait for the response
                response = await client.PostAsync(graphUrl, new FormUrlEncodedContent(queryParams), token);
                var reply = await response.Content.ReadAsStringAsync();
            }
            catch (TaskCanceledException tce)
            {
                // logging code goes here
            }
        }

// Calling code for this method:

await Task.Run(async () =>
        {
            cts = new CancellationTokenSource();
            cts.CancelAfter(60000);
            await RefreshFacebookCacheAsync(releaseUris, cts.Token);

            cts = null;
        });

编辑：

以下是来自Facebook的回复，详情从回复正文中删除：

[
    {
        "code": 200,
        "headers": [
            {
                "name": "Access-Control-Allow-Origin",
                "value": "*"
            },
            {
                "name": "Strict-Transport-Security",
                "value": "max-age=15552000; preload"
            },
            {
                "name": "Expires",
                "value": "Sat, 01 Jan 2000 00:00:00 GMT"
            },
            {
                "name": "Content-Type",
                "value": "text/javascript; charset=UTF-8"
            },
            {
                "name": "Facebook-API-Version",
                "value": "v2.12"
            },
            {
                "name": "Cache-Control",
                "value": "private, no-cache, no-store, must-revalidate"
            },
            {
                "name": "Vary",
                "value": "Accept-Encoding"
            },
            {
                "name": "Pragma",
                "value": "no-cache"
            }
        ],
        "body": "{\"url\":\"https:\\/\\/news.gov.bc.ca\\/releases\\/2017PREM0002-000050\",\"type\":\"article\",\"title\":\"Five conditions secure coastal protection and economic benefits for all British Columbians\",\"image\":[{\"url\":\"https:\\/\\/farm1.staticflickr.com\\/376\\/31446050403_570a0f0cac_b.jpg\"}],\"description\":\"Following the Trudeau government\\u2019s approval of Kinder Morgan\\u2019s Trans Mountain Pipeline Project, the Province\\u2019s clear, consistent and principled position on its five conditions has resulted in tangible and significant investments that will protect British Columbia\\u2019s environmental and economic interests.\",\"updated_time\":\"2018-02-19T17:08:49+0000\",\"pages\":[{\"name\":\"Government of British Columbia\",\"url\":\"https:\\/\\/www.facebook.com\\/BCProvincialGovernment\\/\"}]}"
    }
]

Answer 1

这是我们软件中的时间问题。由于我们的发布流程和我们的API请求的时间稍有延迟，Facebook正在抓取过时的信息。

图表API POST请求间歇性地失败

1 个答案: