feat(Proof): generate image thumbnail (size 400) on upload

[raphodn]

What

New Proof.image_thumb_path field
Generate a size 400 thumbnail with Pillow

Todo

• generate the thumbnail for existing images

[raphodn]

Script to generate thumbnails in staging & prod

from django.conf import settings
from open_prices.proofs.models import Proof
from open_prices.proofs.utils import generate_thumbnail

for proof in Proof.objects.filter(file_path__isnull=False, image_thumb_path__isnull=True):
    try:
        current_dir_id_str = proof.file_path.split("/")[0]
        current_dir = settings.IMAGES_DIR / current_dir_id_str
        file_stem = proof.file_path.split("/")[1].split(".")[0]
        extension = "." + proof.file_path.split("/")[1].split(".")[1]
        mimetype = proof.mimetype

        image_thumb_path = generate_thumbnail(current_dir, current_dir_id_str, file_stem, extension, mimetype)

        Proof.objects.filter(id=proof.id).update(image_thumb_path=image_thumb_path)
    except Exception as e:
        print("===================")
        print(proof.__dict__)
        print(e)

[raphodn]

Generated errors for a few JPEG images

OSError: cannot write mode RGBA as JPEG

fixed here: a7f18e9
thanks to: https://stackoverflow.com/questions/48248405/cannot-write-mode-rgba-as-jpeg#comment108750538_48248432