Method only

tortoise/queryset.py:956–978

Fetch ONLY the specified fields to create a partial model. Persisting changes on the model is allowed only when: * All the fields you want to update is specified in `` .save(update_fields=[...])`` * You included the Model primary key in the `.only(...)``

(self, *fields_for_select: str)

        return queryset  # type: ignore

    def only(self, *fields_for_select: str) -> QuerySet[MODEL]:
        """
        Fetch ONLY the specified fields to create a partial model.

        Persisting changes on the model is allowed only when:

        * All the fields you want to update is specified in ``<model>.save(update_fields=[...])``
        * You included the Model primary key in the `.only(...)``

        To protect against common mistakes we ensure that errors get raised:

        * If you access a field that is not specified, you will get an ``AttributeError``.
        * If you do a ``<model>.save()`` a ``IncompleteInstanceError`` will be raised as the model is, as requested, incomplete.
        * If you do a ``<model>.save(update_fields=[...])`` and you didn&#x27;t include the primary key in the ``.only(...)``,
          then ``IncompleteInstanceError`` will be raised indicating that updates can&#x27;t be done without the primary key being known.
        * If you do a ``<model>.save(update_fields=[...])`` and one of the fields in ``update_fields`` was not in the ``.only(...)``,
          then ``IncompleteInstanceError`` as that field is not available to be updated.
        """
        if not fields_for_select:
            raise ValueError(".only() requires at least one field")
        queryset = self._clone()
        queryset._fields_for_select = fields_for_select
        return queryset

    def select_related(self, *fields: str) -> QuerySet[MODEL]:
        """