fix(GAT-8219): Running out of memory when fetching large collections

[tmillingtonhic]

Screenshots (if relevant)

Screen.Recording.2026-01-05.at.15.01.08.mov

Describe your changes

Issue ticket link

https://hdruk.atlassian.net/browse/GAT-8219

Environment / Configuration changes (if applicable)

Requires migrations being run?

If not using the pre-push hook. Confirm tests pass:

Checklist before requesting a review

• I have performed a self-review of my code
• I have added appropriate unit tests
• I have created mocks for unit tests (where appropriate)
• I have added appropriate Behat tests to confirm AC (if applicable)
• I have added Swagger annotations for new endpoints (if applicable)
• I have added audit logs for new operation logic (if applicable)
• I have added new environment variables to the .env.example file (if applicable)
• I have added new environment variables to terraform repository (if applicable)

[github-actions]

🎉 Great job! Your PR title follows the correct format. 🚀

[loki-sinclair-hdruk]

If we're now streaming the collection data, why do we need the additional memory to store as a variable? Was the original call to the function problematic?

[loki-sinclair-hdruk]

I'd hazard a guess that we're actually using more memory here, just masking with the stream

[tmillingtonhic]

The issue is in returning the json - Laravel uses a large amount of memory constructing the response()->json(). Without calling the response()->json() method it only takes about 30MB to construct the collection. By streaming the json it means we don't have to construct the full json response before returning.

Rewriting $this->getCollectionActiveById to stream the results back would probably reduce memory consumption further but just streaming the json was sufficient for this ticket.