I'm calling a REST API that returns a maximum of 25 items per request. Each response includes a cursor: the first response has only an `after` cursor, middle responses have both `before` and `after`, and the final response has only `before`. I want to keep requesting pages until the response no longer contains an `after` cursor, while collecting every item.
My current approach makes the first request, then enters a `do`/`while` loop and builds the next URL from `$response.result_info.cursors.after`. However, I keep getting an infinite loop or repeatedly requesting the wrong page. I suspect I'm not updating the response and cursor correctly after each iteration. What is the right way to structure this loop in PowerShell?
4 Answers
Use a `do`/`until` or `do`/`while` loop with the current response as the source of the next cursor. Keep the base URL separate, update the response on every iteration, and add each page’s items to a collection. For example:
```powershell
$baseUri = 'https://api.domain.com/items?per_page=25'
$allItems = @()
$response = $null
do {
$uri = if ($response -and $response.result_info.cursors.after) {
"$baseUri&cursor=$($response.result_info.cursors.after)"
} else {
$baseUri
}
$response = Invoke-RestMethod -Uri $uri -Method Get -Headers $headers
$allItems += $response.result
} while ($response.result_info.cursors.after)
```
The important part is that `$response` is replaced with the newest response before the loop condition is checked. Otherwise, the same cursor can be used repeatedly.
A debugger or breakpoint can help verify this quickly. Inspect the generated URI and the value of `cursors.after` on every iteration. Also confirm that the API expects the cursor as a query parameter exactly as shown; some APIs return a complete next-page URL or require URL encoding. Stop when `after` is null or empty, not merely when the response contains a cursor object.
Your original code uses `$response_cursor` for the new request, but the next loop iteration still reads the cursor from `$response`. Assign the new response back to the variable used to build the next URL, or always reference the cursor from `$response_cursor` and then update it consistently. Mixing those two variables is what prevents the cursor from advancing.
Be careful with the URL string. PowerShell does not expand variables inside ordinary single-quoted strings. Use a double-quoted string or the format operator, such as:
```powershell
$uri = "$baseUri&cursor=$($response.result_info.cursors.after)"
```
With single quotes, `$response` and the subexpression are generally passed literally, which can produce a request containing the text `$($response.result_info.cursors.after)` instead of the actual cursor.
That makes sense. I was rebuilding the URL from the original response instead of consistently using the response returned by the previous iteration.