feat: add ebook mode to search, automatically filtering for borrowable ebooks

[ronibhakta1]

Closes # ArchiveLabs/pyopds2_openlibrary#23

Fix: mode=ebooks to Open Library opds /search URL (by default) and this should update the query to include ebook_access:[borrowable TO *] if it’s not present

Technical

Testing

Screenshot

Stakeholders

@MarcCoquand @mekarpeles

[Copilot]

Pull request overview

This PR adds an ebooks mode to the Open Library OPDS /search endpoint that automatically filters search results to include only borrowable ebooks. When mode=ebooks is set (now the default), the endpoint appends ebook_access:[borrowable TO *] to the search query unless it already contains an ebook_access: filter.

Changes:

• Added mode parameter to /opds/search endpoint with default value of "ebooks"
• Implemented automatic query filtering to append ebook_access:[borrowable TO *] when mode is "ebooks" and the filter isn't already present
• Modified the search query construction to use the filtered query when mode is "ebooks"

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[mekarpeles]

As @ronibhakta1 mentions, this PR introduces a mode variable to search, which defaults to ebooks, mirroring to how openlibrary.org/search works.

This PR assumes the default is mode=ebooks.

The opds workflow, from an app's perspective, is that the app will load Open Library's opds feed, will discover that there is a search URL, and then the search URL will be used for searches.

Likely what we want is to have a search URL which also publishes that facets are available for mode whose values can be ebooks or all.

Currently, the PR open has a few problems:

1. It always defaults to ebooks -- what @MarcCoquand wants (it's a decision; not a terrible path, assuming there's some way to get back to mode=everything
2. If we change the mode to mode=everything, no logic exists to remove ebook_access:[borrowable TO *] from the query. (making it impossible to go from ebooks to everything.
3. Consideration: we want to be careful to persist the mode across requests but not to change the query for the user in away that affects the opds feed, otherwise, the feed will include ebook_access:[borrowable TO *] in all future queries, which we probably don't want.

[mekarpeles]

LGTM

[mekarpeles]

Changes now LGTM w/ facet approach + mode

[MarcCoquand]

Hi, is the default now that it defaults to ebooks only? @mekarpeles @ronibhakta1 .

In the PR I see {{?query,mode}} which slightly confuses me, because {?query} is there to indicate that it should be replaced by the OPDS feed. mode is not something supported to be replaced by facets.