Artist/label autocomplete fails to surface exact matches (e.g. "Moon")

[holden]

Problem

Searching for an artist named MOON (artist ID 2439, 1 record on Imperial) is effectively impossible via the artist autocomplete dropdown. The general records search bar does return the record, but it's buried among 20+ other results containing "moon" (Moonglows, Moon Martin, Dead Moon, etc.).

What happens

Artist filter sidebar (/api/artists?q=moon):

• The API uses ILIKE '%moon%' which matches 50+ artists containing "moon" anywhere in their name
• Results are ordered alphabetically by full name and limited to 10 results
• Artists like "AUGUST MOON", "BAIRD, Alton, & Moonlighters", "BLUE MOONS", etc. all sort before "MOON" alphabetically
• The exact match "MOON" never appears in the top 10 results — it's completely unreachable
• Same issue affects the label autocomplete and the record edit form's artist/label fields

General search (/records?search=moon):

• This does return the MOON record (around position 8), but it's easy to miss among Moonglows, Moon Mullican, Moon Martin, Keith Moon, Art Mooney, etc.
• The pg_search ranking doesn't strongly prioritize exact artist name matches

Verified

• Artist "MOON" (ID 2439) exists in the database, created 2010-12-21
• Record ID 17930, condition NM, on Imperial label, genre Psychedelic/Garage
• Directly filtering by artist_id (?q[artist_id_eq]=2439) shows the record correctly
• /api/artists?q=moon returns 10 results — none of which is "MOON"

Root Cause

1. Autocomplete API (/api/artists and /api/labels)

# app/controllers/api/artists_controller.rb
artists = Artist
  .left_joins(:records)
  .where("artists.name ILIKE ?", "%#{sanitized}%")
  .group("artists.id")
  .order(:name)          # <-- Alphabetical only, no relevance
  .limit(10)             # <-- Only 10 results

Pure alphabetical ordering with a hard limit of 10 means exact matches and short names get buried behind longer compound names that happen to sort earlier.

2. General search ranking

The wide_search pg_search scope uses tsearch + trigram, but "moon" as a prefix matches many artists (moonglows, moondog, etc.) with similar relevance scores. The exact artist name match isn't strongly boosted.

Fix

Autocomplete API (primary fix)

Prioritize results by match quality:

1. Exact matches first — MOON when searching "moon"
2. Prefix matches second — MOON, Keith / MOONGLOWS
3. Contains matches last — DEAD MOON / HALF MOON RUN
4. Within each tier, sort by name length (shorter = more relevant), then alphabetically

artists = Artist
  .left_joins(:records)
  .where("artists.name ILIKE ?", "%#{sanitized}%")
  .group("artists.id")
  .order(
    Arel.sql("CASE " \
      "WHEN artists.name ILIKE #{Artist.connection.quote(sanitized)} THEN 0 " \
      "WHEN artists.name ILIKE #{Artist.connection.quote("#{sanitized}%")} THEN 1 " \
      "ELSE 2 END"),
    Arel.sql("LENGTH(artists.name)"),
    :name
  )
  .limit(10)

Apply the same fix to both Api::ArtistsController and Api::LabelsController.

Affected files

• app/controllers/api/artists_controller.rb
• app/controllers/api/labels_controller.rb