Can I generate QRcode for my tickets?

Anvil Q&A
6

Returning a file is the tricky thing here. The method qrcode.make(...).show() returns None and attempts to show the QR code as a GUI window on the server, which doesn’t do anything. You have to make a Media object and return that.

I made an app for a project I work on that generated colourful branded QR codes in SVG format (because editing the colours is easier with an SVG since it’s just text). The server code looks a bit like this:

import anvil.server
import qrcode
import qrcode.image.svg
from io import BytesIO

@anvil.server.callable
@anvil.server.http_endpoint("/qrcode")
def make_qr_code(qr_code_data, **params):
    qr_code_obj = qrcode.make(qr_code_data, 
                              image_factory=qrcode.image.svg.SvgPathImage, 
                              error_correction=qrcode.constants.ERROR_CORRECT_Q,
                              box_size=25, version=2)
    data = BytesIO()
    qr_code_obj.save(data)
    data.seek(0)
    svg_text = data.read()
    return BlobMedia("image/svg+xml", svg_text, name="qrcode.svg")

In the app itself, we just use an Image component called qrcode_image and set the source to be the QR code:

media = anvil.server.call('make_qr_code', "Some text here!")
self.qrcode_image.source = media

If you want an image in PNG format, I’d guess you’ll have to alter the image_factory used, and you’ll likely need to pass the bytes from the BytesIO object into the BlobMedia constructor directly, but I can’t find the documentation for doing so.
(I had this question myself: Can I write to a Media object as a file?)

4 Likes