def train_dataloader(self) -> Optional[TRAIN_DATALOADERS]:
        """The training dataloader(s) used during ``trainer.fit()``."""
        if (combined_loader := self.fit_loop._combined_loader) is not None:
            return combined_loader.iterables
        return None
The training dataloader(s) used during ``trainer.fit()``.
src/lightning/pytorch/trainer/trainer.py