Set default sort order on IIIF collection searches

[kdid]

Sumamry

Fix duplicate items in paginated IIIF collection responses

When requesting pages of a IIIF collection (e.g. ?as=iiif&page=2), items would sometimes appear on multiple pages. Because all works matching collection.id:{id} receive equal relevance scores, OpenSearch returned them in an arbitrary shard-merge order that was not guaranteed to be stable between requests.

The fix applies a default accession_number:asc sort to IIIF collection searches. This is done via a new defaultSort option on doSearch that is applied to the search context after query construction but before the OpenSearch request - keeping it out of query string parameters and pagination URLs, and leaving all other search paths unaffected. An explicit ?sort= parameter from the caller will still take precedence.

To test/verify

Using the tool: https://nulib-labs.github.io/debug-dcapi-paging/

• A collection that is consistently failing on staging with one duplicate is:
  • https://dcapi.rdc-staging.library.northwestern.edu/api/v2/collections/30d59215-8f2b-470d-967b-5a721fa366b7?as=iiif
• Note that same collection works if you manually add the sort param:
  • https://dcapi.rdc-staging.library.northwestern.edu/api/v2/collections/30d59215-8f2b-470d-967b-5a721fa366b7?as=iiif&sort=accession_number:asc
• Same collection on my deployed dev branch also works:
  • https://dcapi-kdid.rdc-staging.library.northwestern.edu/api/v2/collections/30d59215-8f2b-470d-967b-5a721fa366b7?as=iiif
• Berkeley also has duplicates if you feel like waiting:
  • https://dcapi.rdc-staging.library.northwestern.edu/api/v2/collections/18ec4c6b-192a-4ab8-9903-ea0f393c35f7?as=iiif
  • https://dcapi-kdid.rdc-staging.library.northwestern.edu/api/v2/collections/18ec4c6b-192a-4ab8-9903-ea0f393c35f7?as=iiif

[mathewjordan]

Looks great and works well for me!