Function getMatchQueries

middleware/api/es-search.js:165–351

(query, { usePrefixSearch, fuzzy })

}

function getMatchQueries(query, { usePrefixSearch, fuzzy }) {
  const BOOST_PHRASE = 10.0
  const BOOST_TITLE = 4.0
  const BOOST_HEADINGS = 3.0
  const BOOST_CONTENT = 1.0
  const BOOST_AND = 2.5
  const BOOST_EXPLICIT = 3.5
  // Number doesn't matter so much but just make sure it's
  // boosted low. Because we only really want this to come into
  // play if nothing else matches. E.g. a search for `Acions`
  // which wouldn't find anythig else anyway.
  const BOOST_FUZZY = 0.1

  const matchQueries = []

  // If the query input is multiple words, it's good to know because you can
  // make the query do `match_phrase` and you can make `match` query
  // with the `AND` operator (`OR` is the default).
  const isMultiWordQuery = query.includes(' ') || query.includes('-')

  if (isMultiWordQuery) {
    // If the query contains spaces, prioritize a "match phrase" query
    // beyond a regular "match" query.
    // Basically, that means if you search for 'foo bar' we'd rather
    // rank:
    //     "A common term is foo bar which is often used"
    // above:
    //     "Some people use foo"
    //     "Bar is also a common term"
    //
    // So that, when all are matched you get this rank:
    //     1. "A common term is foo bar which is often used"
    //     2. "Some people use foo"
    //     3. "Bar is also a common term"
    //
    // But note, a "match phrase" isn't the holy panacea of matches.
    // In particular, just because there exists a document whose *content*
    // contains the phrase "... foo bar ..." we might still prefer the
    // matches on title that contains the words *separately*. This
    // is why a 'match_phrase' on 'content' has a lesser boost
    // that a 'match' on 'title'.
    const matchPhraseStrategy = usePrefixSearch ? 'match_phrase_prefix' : 'match_phrase'
    matchQueries.push(
      ...[
        {
          [matchPhraseStrategy]: {
            title_explicit: { boost: BOOST_EXPLICIT * BOOST_PHRASE * BOOST_TITLE, query },
          },
        },
        { [matchPhraseStrategy]: { title: { boost: BOOST_PHRASE * BOOST_TITLE, query } } },
        {
          [matchPhraseStrategy]: {
            headings_explicit: { boost: BOOST_EXPLICIT * BOOST_PHRASE * BOOST_HEADINGS, query },
          },
        },
        { [matchPhraseStrategy]: { headings: { boost: BOOST_PHRASE * BOOST_HEADINGS, query } } },
      ]
    )