How to join associated models of a PgSearch Document to apply dynamic filter

document.rb

class PgSearch::Document
  belongs_to :article, -> {where("searchable_type = 'Article'")}, 
             foreign_key: 'searchable_id'

  belongs_to :info, -> {where("searchable_type = 'Info'")}, 
             foreign_key: 'searchable_id'
end

@searched = PgSearch.multisearch(@query).
      with_pg_search_highlight.
      includes(:searchable).
      left_outer_joins(:info, :article).
      where("infos.lang = :lang OR articles.lang= :lang", lang: I18n.locale)