Django admin file upload with current model id

Question

I'm trying to create a simple photo gallery with the default Django admin. I'd like to save a sample photo for each gallery, but I don't want to keep the filname. Instead of the filename, I'd like to save the id of the model (N.jpg). But the first time I want to save the object the id does not exist. How could I know the next auto increment in the model, or somehow save the model data before the upload with super.save and after upload the file when self.id is exists? Is there a cool solution?

Something like this:

def upload_path_handler(instance, filename):
    ext = filename extension
    return "site_media/images/gallery/{id}.{ext}".format(id=instance.nextincrement, ext=ext)

class Gallery(models.Model):
    name  = models.TextField()
    image = models.FileField(upload_to=upload_path_handler)

And maybe store the filename in a different field.

Answer 1

I ran into the same problem. Okm's answer sent me on the right path but it seems to me it is possible to get the same functionality by just overriding the save() method of your Model.

def save(self, *args, **kwargs):
    if self.pk is None:
        saved_image = self.image
        self.image = None
        super(Material, self).save(*args, **kwargs)
        self.image = saved_image

    super(Material, self).save(*args, **kwargs)

This definitely saves the information correctly.