def val_dataloaders(self) -> Optional[EVAL_DATALOADERS]:
        """The validation dataloader(s) used during ``trainer.fit()`` or ``trainer.validate()``."""
        if (combined_loader := self.fit_loop.epoch_loop.val_loop._combined_loader) is not None or (
            combined_loader := self.validate_loop._combined_loader
        ) is not None:
            return combined_loader.iterables
        return None
The validation dataloader(s) used during ``trainer.fit()`` or ``trainer.validate()``.
src/lightning/pytorch/trainer/trainer.py