Add typeahead + multi-select opt-ins for controlled compound members

[laritakr]

Issue:

• Enable contributors to be given multiple roles for a given work research-technologies/enact_knapsack#92
• Ensure usability for metadata fields with large lists of items (typeahead drop downs) research-technologies/enact_knapsack#93

Summary

Adds two opt-in, per-member form: flags for compound controlled metadata members in the M3 profile. Both default off, so existing controlled members render exactly as before.

• autocomplete: true — binds a select2 typeahead over the member's <select>. The full option list is already in the DOM, so filtering is client-side (no extra request). Works for single- and multi-select.
• multiple: true — renders a <select multiple>. At submit time each selected value fans out into its own compound entry, sharing the row's other members (cartesian product when a row has more than one multiple member). A contributor picked with three roles is stored as three single-role entries, not one entry holding an array.

Screenshots

Deposit form — Name and Role controls aligned (empty state):

Multi-select typeahead with several roles chosen (pills wrap in one box, no overflow):

Edit round-trip — one saved row's roles reopen as separate preselected entries:

Show pg

** MOBILE VIEW **

Details

The key design decision is fan-out: the stored shape stays uniform — every member value is a scalar, whether or not the member is multi-select. Consumers never branch on array-vs-scalar, and each term indexes and facets independently. The array only exists transiently between form submit and fan-out; the indexer and show renderer were hardened to tolerate a transient array value because an invalid submission is echoed back before fan-out runs.

Changed (all form / index / render path — nothing touches persistence):

• app/services/hyrax/compound_schema.rb — normalize_subproperty reads form.autocomplete / form.multiple into the spec (default false).
• app/forms/concerns/hyrax/compound_field_behavior.rb — the load-bearing change: fans a multi-select row out into one entry per value.
• app/views/hyrax/compounds/_compound_row.html.erb — multiple → <select multiple> with [] name; autocomplete → data-hyrax-compound-controlled + placeholder.
• app/assets/javascripts/hyrax/compound_metadata.js — bindControlledSelects binds select2 v3 to native selects, on load and on cloned rows.
• app/indexers/.../compound_indexer.rb, app/renderers/.../compound_attribute_renderer.rb, app/helpers/hyrax/compound_fields_helper.rb, app/services/hyrax/compound_subproperty_labeler.rb — tolerate/represent an array member value.
• config/locales/hyrax.en.yml — new compound_fields.search placeholder key.
• documentation/compound_fields.md — new section + type-table row.

Behavior holds in both flexible and non-flexible modes (the compound list comes from the effective schema either way). The Enact profile opt-in (adding these flags to contributor_role) is a separate follow-up in enact_knapsack, not part of this PR.

Testing

Unit/spec coverage added for: schema flag parsing, fan-out (several values → several entries; single value → one scalar; blank handling), array-tolerant indexer/renderer/helper/labeler, and a new view spec for the multi/autocomplete markup. Green on all CI test apps (koppie, dassie, allinson, sirenia).

Manual end-to-end verification in a flexible-mode deposit form (allinson), with autocomplete: true + multiple: true on a controlled compound member:

• role control renders as a select2 typeahead over a native <select multiple>; typing filters client-side;
• picking two roles for one participant, saving → the row fans out into two separate scalar entries on the show page (Name / Role per entry), each faceting independently;
• reopening edit → the two entries re-collapse into their rows, each preselected;
• "Add" clones a row whose select is also a searchable multi-select.

select2 styling

select2 v3 copies the control's .form-control classes onto its own container (Bootstrap border + fixed .form-control-sm height) while rendering its own bordered inner box, producing a "box within a box" and clipping a multi-select's chosen pills. _compound_metadata.scss flattens the inner box so only the form-control frame shows and lets the frame grow to fit the selected values. Verified in a flexible-mode deposit form (single clean box; multiple pills wrap without overflowing into the next field).

[github-actions]

Test Results

    17 files      17 suites   3h 29m 46s ⏱️
 7 978 tests  7 671 ✅ 307 💤 0 ❌
27 275 runs  26 676 ✅ 599 💤 0 ❌

Results for commit 7c49539.

♻️ This comment has been updated with latest results.

[Copilot]

Pull request overview

Adds opt-in enhancements for compound controlled members so profiles can enable (1) a select2-backed typeahead over an existing <select> and (2) multi-select submission with server-side fan-out into scalar-valued compound entries, while preserving default/backward-compatible rendering when the flags are off.

Changes:

• Parse new per-subproperty form.autocomplete / form.multiple flags into the compound schema spec and render controlled members accordingly.
• Implement multi-select fan-out in compound form deserialization and harden indexing/show rendering paths to tolerate transient array values.
• Add JS/CSS to bind select2 for controlled selects and adjust styling; add locale/docs + comprehensive specs.

Reviewed changes

Copilot reviewed 17 out of 17 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
spec/views/hyrax/compounds/_compound_row_controlled_multiple_spec.rb	Adds view coverage for controlled multi-select + typeahead markup and backward-compat single-select behavior.
spec/services/hyrax/compound_schema_spec.rb	Verifies schema parsing for the new form flags and updated normalized specs.
spec/renderers/hyrax/renderers/compound_attribute_renderer_spec.rb	Covers show rendering when a controlled value is temporarily an array.
spec/indexers/hyrax/indexers/compound_indexer_spec.rb	Covers indexing behavior when a member value is an array (flattening into facet values).
spec/helpers/hyrax/compound_fields_helper_spec.rb	Adds helper coverage for array current values (options + forced-value detection).
spec/forms/concerns/hyrax/compound_field_behavior_spec.rb	Adds coverage for multi-select fan-out behavior during deserialization.
documentation/compound_fields.md	Documents the two new controlled-member opt-ins and fan-out semantics.
config/locales/hyrax.en.yml	Adds i18n placeholder text for controlled select2 search.
app/views/hyrax/compounds/_compound_row.html.erb	Renders multiple controlled selects ([] name), adds select2 hook + placeholder for autocomplete.
app/services/hyrax/compound_subproperty_labeler.rb	Makes label resolution tolerant of array values by joining term labels.
app/services/hyrax/compound_schema.rb	Normalizes form.autocomplete / form.multiple into subproperty specs (default false).
app/renderers/hyrax/renderers/compound_attribute_renderer.rb	Renders array controlled values as comma-separated term markup.
app/indexers/hyrax/indexers/compound_indexer.rb	Flattens array member values during indexing to avoid nested arrays in Solr fields.
app/helpers/hyrax/compound_fields_helper.rb	Ensures option lists / forced-value logic handle array current values.
app/forms/concerns/hyrax/compound_field_behavior.rb	Implements multi-select fan-out and normalization in compound deserialization.
app/assets/stylesheets/hyrax/_compound_metadata.scss	Adds select2 styling adjustments for controlled members (to avoid “double box” + pill clipping).
app/assets/javascripts/hyrax/compound_metadata.js	Adds select2 binding for controlled selects, including on cloned rows.

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[ShanaLMoore]

I ran this locally and can confirm this is working. cc @laritakr screenshots attached in the description.

[orangewolf]

there is a lot of variable setting in this view. it makes me think the whole thing needs to be a helper (and therefor tested)

[ShanaLMoore]

Good call; extracted the whole controlled branch into a compound_controlled_select helper (plus a small compound_controlled_data), so the view is now just <%= compound_controlled_select(spec, value, input_name, input_id) %>. The multiple / autocomplete / force-select logic is now unit-tested in spec/helpers/hyrax/compound_fields_helper_spec.rb. Done in 90e7b01.