Fix bug in tortoise.models.Model When a QuerySet uses the only func…

…tion and then uses the print function to print the returned result, an AttributeError is generated (#1724)

Co-authored-by: gongchangku <gongchangku@anban.tech>

CHANGELOG.rst

@@ -20,6 +20,7 @@ Fixed
 - Fix mysql uuid compression bug (#1687)
 - Fix comment for fk fields without constraint for mysql (#1679)
 - Removed no_delay option for postgres, as it wasn't doing anything (#1677)
+- Fix bug in `tortoise.models.Model` When a QuerySet uses the only function and then uses the print function to print the returned result, an AttributeError is generated. (#1723)
 
 0.21.5 <../0.21.5>`_ - 2024-07-18
 ------

tortoise/models.py

@@ -781,7 +781,7 @@ def __eq__(self, other: object) -> bool:
         return type(other) is type(self) and self.pk == other.pk  # type: ignore
 
     def _get_pk_val(self) -> Any:
-        return getattr(self, self._meta.pk_attr)
+        return getattr(self, self._meta.pk_attr, None)
 
     def _set_pk_val(self, value: Any) -> None:
         setattr(self, self._meta.pk_attr, value)