Create ZIP file in memory from PIL images and serve with Flask

README.md

First do pip install flask Pillow in your venv :)

app.py

from flask import Flask, send_file

import memoryzip

app = Flask(__name__)

# This config var saves headaches with CacheControl when developing
app.config['SEND_FILE_MAX_AGE_DEFAULT'] = -1

@app.route('/downloader')
def download():

	# Output 4 image files this time:
    list_of_tuples = [(f'{i}.png', memoryzip.get_image_buffer(memoryzip.fetch_image()))
                      for i in range(1,5)]
               		  
    buff = memoryzip.get_zip_buffer(list_of_tuples)
    
    return send_file(buff,
    	             mimetype='application/zip',
    	             as_attachment=True,
    	             attachment_filename='memoryzip.zip')

memoryzip.py

import io
import zipfile

from PIL import Image

def fetch_image():
    ''' mock function to return pil image'''
    return Image.new('RGB', (400, 300))

def get_image_buffer(image):
    img_buffer = io.BytesIO()
    image.save(img_buffer, 'PNG')
    img_buffer.seek(0)
    
    return img_buffer

def get_zip_buffer(list_of_tuples):
    zip_buffer = io.BytesIO()
    
    # https://stackoverflow.com/a/44946732 <3   
    with zipfile.ZipFile(zip_buffer, "a", zipfile.ZIP_DEFLATED, False) as zip_file:
        for file_name, data in list_of_tuples:
            zip_file.writestr(file_name, data.read())

    zip_buffer.seek(0)
    return zip_buffer

if __name__ == '__main__':
    # Usage
    list_of_tuples = [('1.png', get_image_buffer(fetch_image())),
                      ('2.txt', io.BytesIO(b'i am text'))]

    with open('test.zip', 'wb') as f:
        f.write(get_zip_buffer(list_of_tuples).getvalue())

When you are trying to serve it via Flask, does that package exist? Its not in the python library nor on pip

Sorry, that's referring to the memoryzip.py module, which is the second file in this gist! You should save this alongside your app.py.