如何在Python中为document_client对象发送的Cosmos DB查询设置延续令牌? [英] How do I set continuation tokens for Cosmos DB queries sent by document_client objects in Python?

问题描述

我有一个API，该API根据文档字段中显示的关键字来检索文档.我想对结果进行分页，以便可以将文档返回给发送请求的客户端，并允许他们在需要时请求更多文档.当我在Azure数据资源管理器中时，查询本身在浏览器中只需要一秒钟左右的时间，但是当我使用Python DocumentDB库进行查询时，查询只需要一分钟的时间.

I have an API that retrieves documents based on keywords that appear in document fields. I would like to paginate results so that I can return documents to a client sending a request, as well as allowing them to request more documents if they want. The query itself only takes a second or so in the browser when I am in the Azure Data Explorer, but it takes about a minute when I query using the Python DocumentDB library.

查看

Looking at the Microsoft Cosmos DB REST API, it appears as if there are two tokens, x-ms_continuation and x-ms-max-item-count that are used.

似乎没有将这些作为条目放入document_client.QueryDocuments()的 options 字典中的方法.

It doesn't appear that putting these as entries in the options dictionary of document_client.QueryDocuments() does the trick.

在GitHub存储库中，阅读()方法引用 options 参数:

In the GitHub repository, the Read() method references the options parameter:

    headers = base.GetHeaders(self,
                              initial_headers,
                              'get',
                              path,
                              id,
                              type,
                              options)
    # Read will use ReadEndpoint since it uses GET operation
    url_connection = self._global_endpoint_manager.ReadEndpoint
    result, self.last_response_headers = self.__Get(url_connection,
                                                    path,
                                                    headers)

查看 base.py ，文件所在的位置，我看到了这两个代码块

Looking in base.py, where the file is located, I saw these two blocks of code

if options.get('continuation'):
    headers[http_constants.HttpHeaders.Continuation] = (
        options['continuation'])

if options.get('maxItemCount'):
    headers[http_constants.HttpHeaders.PageSize] = options['maxItemCount']

这似乎与上面的两个参数相对应.但是，当我将它们设置为查询({'continuation':True,'maxItemCount':10})中的选项时，没有任何变化.

This would appear to correspond to the two parameters above. However, when I set them as options in the query ({'continuation':True,'maxItemCount':10}), nothing changes.

最终查询看起来像

client.QueryDocuments(collection_link, query, {'continuation':True,'maxItemCount':10})

我还尝试使用字符串代替maxItemCount的int.

I have also tried using a string instead of an int for maxItemCount.

我在这里做错了什么?

标题与上述文档中的两个标题相同，来自

The headers are the same as the two from the documentation above, from http_constants.py:

# Our custom DocDB headers
Continuation = 'x-ms-continuation'
PageSize = 'x-ms-max-item-count'

推荐答案

事实证明，需要从结果对象本身处理查询结果，并且应调用方法_fetch_function(options):

It turns out that the query results needed to be handled from the results object itself, and the method _fetch_function(options) should be called:

q = client.QueryDocuments(collection_link, query, {'maxItemCount':10})
results_1 = q._fetch_function({'maxItemCount':10})
#this is a string representing a JSON object
token = results_1[1]['x-ms-continuation']
results_2 = q._fetch_function({'maxItemCount':10,'continuation':token})

数据包含在results_[n][0]中，并且从调用返回的标头信息在results_[n][1]中返回.

The data is contained in results_[n][0] and header information returned from the call is returned in results_[n][1].

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