- ext = doc.meta.get_one(DCNS('relation.coverimage.url')).rsplit('.', 1)[-1].lower()
- if ext not in ('jpg', 'jpeg', 'png', 'gif', 'tif', 'tiff'):
- raise ValidationError('Invalid cover image format, should be an image file (jpg, png, gif). '
- 'Change it in Metadata.')
+ cover_url = doc.meta.get_one(DCNS('relation.coverimage.url'))
+ if cover_url:
+ ext = cover_url.rsplit('.', 1)[-1].lower()
+ if ext not in ('jpg', 'jpeg', 'png', 'gif', 'tif', 'tiff'):
+ raise ValidationError('Invalid cover image format, should be an image file (jpg, png, gif). '
+ 'Change it in Metadata.')