neuralib.sqlp.annotation.foreign

neuralib.sqlp.annotation.foreign(*field, update='NO ACTION', delete='NO ACTION')[source]

A decorator to create a foreign constraint.

Common use:

With a foreign table

>>> class ForeignTable:
...     a: Annotated[str, str]
...     b: Annotated[str, str]

  1. mapping one-by-one

>>> class Example:
...     a: Annotated[str, str]
...     b: Annotated[str, str]
...     @foreign(ForeignTable.a, ForeignTable.b)
...     def _foreign(self):
...         return self.a, self.b

  1. by default, with the primary keys for the referred foreign table.

>>> class Example:
...     a: Annotated[str, str]
...     b: Annotated[str, str]
...     @foreign(ForeignTable)
...     def _foreign(self):
...         return self.a, self.b

  1. Self refered.

>>> class Example:
...     a: Annotated[str, str]
...     b: Annotated[str, str]
...     @foreign('a')
...     def _foreign(self):
...         return self.b
Parameters:

  • field – a foreign table or foreign fields.

  • update (Literal['SET NULL', 'SET DEFAULT', 'CASCADE', 'RESTRICT', 'NO ACTION']) – update policy

  • delete (Literal['SET NULL', 'SET DEFAULT', 'CASCADE', 'RESTRICT', 'NO ACTION']) – delete policy