Saving model to HF broken _save_pretrained method doesn't exist

[Sukh-P]

Describe the bug

Currently when trying to save a model to HF with the code in the main branch one would encounter this error:

AttributeError: 'Model' object has no attribute '_save_pretrained'

I believe this happens now since in this commit the PyTorchModelHubMixin class was removed, it turns out that we were using the _save_pretrained method from it in our base model save_pretrained method

So I think there are two ways this could be fixed:

• Either by reintroducing the PyTorchModelHubMixin and inheriting from it
• Or if the PyTorchModelHubMixin is unnecessary overhead just for that one method (I am assumed it isn't used elswhere) we could implement our own '_save_pretrained' method to save model weights locally, wouldn't be too hard I think since the method HF uses looks quite straightforward, I tried just a torch.save() replacement but that seems to not quite work but hopefully not too much more complicated than something like that, @peterdudfield would be good to get your opinion as you probably have most context for the pros/cons of removing the PyTorchModelHubMixin class

[peterdudfield]

Interesting, do you know wen this PytorchModelHubMixin was removed? and why?

I guess it was removed to make it cleaner? or there was some comptability issue?

[Sukh-P]

@peterdudfield I think the commit with that change was created by yourself https://github.com/openclimatefix/PVNet/pull/238/files so I was hoping you may be able to shed some light on that part 😄

[peterdudfield]

ah, not sure, my mistale for not testing it properly, is it easy to put back in?

[Sukh-P]

Yep it is straight forward, just wanted to check there wasn't a specific reason we wanted to remove it since as I mentioned I think we could implement something ourself to avoid using it