I try to import the library of pyqrcode to generate QR code for each ticket in my table. But looks like anvil doesn’t support this library of pyqrcode?
https://anvil.works/doc/#python_packages is the list of server-side packages. I think I remember a qrcode package there, but I’m not sure of the spelling. You might want to have a look.
yes, anvil has qrcode but not pyqrcode, I will explore it. Thanks!
I have no problem with my local python qrcode module. but with anvil, I tried to use alert(Image()) to present the qrcode, but there is nothing in alert. Did I miss anything?
I’ve not tried putting an Image control directly as the content in an alert box before (I will try it later), but maybe try putting an image control on a form you show in the alert box?
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?)
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I’m forgetting myself - you can’t return an image from a server function to the client, you have to, as @j.sharkey13 correctly says, store it in a media object and return that.
I was tired when I wrote that …
