class CustomJSONB(sqlalchemy.types.TypeDecorator):

  impl = sqlalchemy.dialects.postgresql.JSONB

  def process_bind_param(self, value, _):
    if value is None:
      return None
    return some_modification_to_value(value)

  def process_result_value(self, value, _):
    if value is None:
      return None
    return some_modification_to_value(value)

  def coerce_compared_value(self, op, value):
    # Tells the expression generator to not to try and coerce comparison values using the processors
    # defined above. Instead, it will use the default JSON comparison operators, which is what we
    # want.
    return self.impl.coerce_compared_value(op, value)