build_constraint

# File activerecord/lib/active_record/associations/join_dependency/join_association.rb, line 111
        def build_constraint(reflection, table, key, foreign_table, foreign_key)
          constraint = table[key].eq(foreign_table[foreign_key])

          if reflection.klass.finder_needs_type_condition?
            constraint = table.create_and([
              constraint,
              reflection.klass.send(:type_condition, table)
            ])
          end

          constraint
        end