build_joins

# File activerecord/lib/active_record/relation/query_methods.rb, line 1042
    def build_joins(manager, joins)
      buckets = joins.group_by do |join|
        case join
        when String
          :string_join
        when Hash, Symbol, Array
          :association_join
        when ActiveRecord::Associations::JoinDependency
          :stashed_join
        when Arel::Nodes::Join
          :join_node
        else
          raise 'unknown class: %s' % join.class.name
        end
      end

      build_join_query(manager, buckets, Arel::Nodes::InnerJoin)
    end