Chewy multi-index search

chewy.rb

Chewy.filter :chewy_ngram,
             type: 'edge_ngram',
             min_gram: 1,
             max_gram: 50

Chewy.analyzer :chewy_fulltext_search,
               type: 'custom',
               tokenizer: 'standard',
               filter: %w[lowercase asciifolding chewy_ngram]

global_search.rb

class GlobalSearch
  def self.search(query)
    index_classes = [UsersIndex, ProductsIndex]

    bool_queries = index_classes.map do |index_class|
      {
        bool: {
          filter: [
            { term: { _index: index_class.global_search_fields } }
          ]),
          must: {
            multi_match: {
              query: query,
              fields: index_class.global_search_fields
            }
          }
        }
      }
    end

    index_classes[0].indices(*index_classes[1..]).query(
      bool: { should: bool_queries }
    )
  end
end

products_index.rb

class ProductsIndex < Chewy::Index
  settings analysis: {
    analyzer: %w[chewy_fulltext_search]
  }

  index_scope Product

  field :title, type: 'text', analyzer: 'chewy_fulltext_search'
  field :brand, type: 'text', analyzer: 'chewy_fulltext_search'
  field :description, type: 'text', analyzer: 'chewy_fulltext_search'

  field :updated_at, type: 'date'

  def self.global_search_fields
    %w[title brand description]
  end
end

users_index.rb

class UsersIndex < Chewy::Index
  settings analysis: {
    analyzer: %w[chewy_fulltext_search]
  }

  index_scope User.active

  field :username, type: 'text', analyzer: 'chewy_fulltext_search'
  field :name, type: 'text', analyzer: 'chewy_fulltext_search'
  field :bio, type: 'text', analyzer: 'chewy_fulltext_search'

  field :updated_at, type: 'date'

  def self.global_search_fields
    %w[username name bio]
  end
end