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SaaS Pagination

These pagination strategies allow fidesops to incrementally retrieve content from SaaS APIs. APIs can vary in the way subsequent pages are accessed so these configurable options aim to cover a majority of common use cases.

Supported strategies

  • offset: Iterates through the available pages by incrementing the value of a query param.
  • link: Uses links returned in the headers or the body to get to the next page.
  • cursor: Uses a value from the last-retrieved object to use as a query param pointing to the next set of results.

Offset

This strategy can be used to iterate through pages, or to define the offset for a batch of results. In either case, this strategy increments the specified query param by the increment_by value until no more results are returned or the limit is reached.

Configuration details

  • incremental_param (str): The query param to increment the value for.
  • increment_by (int): The value to increment the incremental_param after each set of results.
  • limit (str): The max value the incremental_param can reach.

Example

This example would take the page query param and increment it by 1 until the limit of 10 is reached or no more results are returned (whichever comes first). 

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pagination:
  strategy: offset
  configuration:
    incremental_param: page
    increment_by: 1
    limit: 10

This strategy is used when the link to the next page is provided as part of the API response. The link is read from the headers or the body and used to get the next page of results.

Configuration details

  • source (str): The location to get the link from, can be either headers or body.
  • path (str): The expression used to refer to the location of the link within the headers or the body.

Examples

The source value of headers is meant to be used with responses following RFC 5988. 

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Link: <https://api.host.com/conversations?page_ref=ad6f38r3>; rel="next",
      <https://api.host.com/conversations?page_ref=gss8ap4g>; rel="prev"
Given this Link header, we can specify a rel of next (case-insensitive). This indicates that we are looking in the Link header with a rel of next. 
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pagination:
  strategy: link
  configuration:
    source: headers
    rel: next

We can also access links returned in the body. If we receive this value in the body: 

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{
  ...
  "next_page": {
      "url": "https://api.host.com/conversations?page_ref=ad6f38r3"
  }
  ...
}
We can use the path value of next_page.url as the expression to access the url. 
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pagination:
  strategy: link
  configuration:
    source: body
    path: next_page.url

Cursor

This strategy is used when a specific value from a response object is used as a cursor to determine the starting point for the next set of results.

Configuration Details

  • cursor_param (str): The name of the query param to assign the cursor value to.
  • field (str): The field to read from the most recently retrieved object to use as the cursor value.

Examples

If an API request returns the following: 

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{
  "messages": [
      {"id": 1, "msg": "this is"},
      {"id": 2, "msg": "a"}
      {"id": 3, "msg": "test"}
  ]
}
This strategy will take the field id from the last item returned and generate a new request with a query param of after=3 
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pagination:
  strategy: cursor
  configuration:
    cursor_param: after
    field: id

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