Question

How can I use parameters to control API calls dynamically in Power Query?
I want to retrieve data from a web API in Power BI and make the request dynamic using user-defined parameters like date ranges, IDs, or page numbers. The goal is to make the API call adaptable without modifying the query each time. What is the recommended approach using Power Query parameters and Web.Contents to build a dynamic and refreshable API connection?

Answer 1

Power Query can manage API calls dynamically by allowing you to create user-defined parameters that can then be used directly on the Web. Contents function. For example, modifying query dates, IDs, or pagination controls no longer necessitates working within the core portion of the M code to alter the definition. The result is a more flexible, refreshable Power BI report.

Create parameters for each dynamic input in Power Query, such as StartDate, EndDate, and PageNumber. Parameters act like variables that users or other queries can refer to. Construct your API URL by concatenating the base endpoint and these parameters using M language. For example:

let
    url = "https://api.example.com/data?startDate=" & StartDate & "&endDate=" & EndDate & "&page=" & Number.ToText(PageNumber),
    source = Json.Document(Web.Contents(url))
in
    source

Let the parameters be accessible at refresh time, especially when publishing the report to the Power BI Service—marking them as required and/or providing default values. This makes the API easier to use in terms of maintainability and scalability, especially when paginated or filtered API endpoints come into play.