Power Query中的分页REST API结果
Power Query中的分页REST API结果
提问于 2021-03-31 21:16:27
我正在尝试从一个带有Power Query的REST API获取数据。该API以200条记录为一页返回结果。每个页面将包含一个JSON结构，如下所示：
{
"start": 0,
"limit": 200,
"records": [
{
"record": {
"id": 1,
"field1": "some text",
"field2": false
}
},
{
"record": {
"id": 2,
"field1": "some text",
"field2": true
}
},
{
"record": {
"id": 3,
"field1": "some text",
"field2": false
}
}
]
}然后，对于下一页，我为start参数提供了一个值，该值以200为增量递增，我只需要用新页面数组的内容扩展records数组。因此，在伪代码中，它看起来是这样的：
content ← True
i ← 1
While content
response ← get(url, http_parameters=['start' = i])
results ← results + response['records']
i ← i + response['size']
content ← size(response['records']) > 0
Endwhile我在Python中很容易做到这一点，但我看不出M语言是如何做到这一点的，因为它没有for或while循环。我见过许多关于这个主题的问题，但每次都假设第一个响应将返回记录总数，或者它包含指向下一个页面的URL。
学习这门语言的过程相当陡峭，所以如果能给我一些建议，我将不胜感激。
回答 2
Stack Overflow用户
发布于 2021-04-01 03:07:35
标准的出发点是根据您的需要调整Microsoft helper function。
// The getNextPage function takes a single argument and is expected to return a nullable table
Table.GenerateByPage = (getNextPage as function) as table =>
let
listOfPages = List.Generate(
() => getNextPage(null), // get the first page of data
(lastPage) => lastPage <> null, // stop when the function returns null
(lastPage) => getNextPage(lastPage) // pass the previous page to the next function call
),
// concatenate the pages together
tableOfPages = Table.FromList(listOfPages, Splitter.SplitByNothing(), {"Column1"}),
firstRow = tableOfPages{0}?
in
// if we didn't get back any pages of data, return an empty table
// otherwise set the table type based on the columns of the first page
if (firstRow = null) then
Table.FromRows({})
else
Value.ReplaceType(
Table.ExpandTableColumn(tableOfPages, "Column1", Table.ColumnNames(firstRow[Column1])),
Value.Type(firstRow[Column1])
);Stack Overflow用户
发布于 2021-04-01 03:11:11
标准的出发点是根据您的需要调整Microsoft helper function。
还有some good blogs on the topic。递归/迭代让我头脑发热，直到我发现它是我们的，然后它就变得甜蜜了。
// The getNextPage function takes a single argument and is expected to return a nullable table
Table.GenerateByPage = (getNextPage as function) as table =>
let
listOfPages = List.Generate(
() => getNextPage(null), // get the first page of data
(lastPage) => lastPage <> null, // stop when the function returns null
(lastPage) => getNextPage(lastPage) // pass the previous page to the next function call
),
// concatenate the pages together
tableOfPages = Table.FromList(listOfPages, Splitter.SplitByNothing(), {"Column1"}),
firstRow = tableOfPages{0}?
in
// if we didn't get back any pages of data, return an empty table
// otherwise set the table type based on the columns of the first page
if (firstRow = null) then
Table.FromRows({})
else
Value.ReplaceType(
Table.ExpandTableColumn(tableOfPages, "Column1", Table.ColumnNames(firstRow[Column1])),
Value.Type(firstRow[Column1])
);页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/66888658
复制相关文章
相似问题
腾讯云开发者
