modify an attribute of the dataset associated with the train_dataloader of the datamodule

[malfonsoarquimea]

Hi! I am working on a project where I need to change an attribute of the dataset that is loaded into the train_dataloader in the datamodule that I pass to the train.fit()
What I am actually trying is something like this in the on_train_epoch_start(self)
self.trainer.datamodule.train_dataloader().dataset.attribute=5
but it doesn't change and it remains unchanged

What am I doing wrong?
thanks!