read an RFID tag and display it with tkinter-CodePudding

I trying to display some tag informations on Tkinter interface. but i have a loop for trying to read a tag on my RFID reader and an other loop for Tkinter.

How i can update the Label in the "on_connect" function when a tag is discovered?

i have this:

from tkinter import *
import nfc
from binascii import hexlify

root = Tk()

tagId = Label(root, text=("Tag n°: " ))
tagId.grid(column=5, row=1, columnspan=3)
root.mainloop()


def on_connect(tag):
    tagId['text'] = "Tag n°: "   hexlify(tag.identifier).decode().upper()


def on_release(tag):
    tagId['text'] = "Tag n°: "


rdwr_options = {
    "targets": ("106A", "106B", "212F"),
    'interval': 0.35,  
    "on-connect": on_connect,
    "on-release": on_release,
    'beep-on-connect': False,
}


if __name__ == "__main__":
    with nfc.ContactlessFrontend() as clf:
        if not clf.open('usb:072f:2200'):
            raise RuntimeError("Failed to open NFC device.")

        while True:
            ret = clf.connect(rdwr=rdwr_options)
            if not ret:
                break

CodePudding user response：

tagId['text'] = "Tag n°: "   hexlify(tag.identifier).decode().upper()

Instead of the above Syntax use the syntax present below

tagId.config(text = "Tag n°: "   hexlify(tag.identifier).decode().upper())

CodePudding user response：

You could try making use of the Label's textvariable parameter like so

from tkinter import *
import nfc
from binascii import hexlify


root = Tk()

tag_text = StringVar()  # create a variable to store the tag text
# bind that variable to your label with 'textvariable'
tagId = Label(root, textvariable=tag_text)
tag_text.set('Tag n°: ')  # set your label's default text

tagId.grid(column=5, row=1, columnspan=3)
root.mainloop()


def on_connect(tag):
    tag_content = hexlify(tag.identifier).decode().upper()
    tag_text.set(f'Tag n°: {tag_content}')


def on_release():
    tag_text.set('Tag n°:')

Whenever you call set() on the textvariable, your tagId label's text will be updated automatically

I do suspect, however, that the While True infinite loop is preventing tkinter from updating. You should instead try using the tkinter after() method to periodically call clf.connect(rdwr=rdwr_options) at a given interval while still allowing tkinter to update your root window

rdwr_options = {
    "targets": ("106A", "106B", "212F"),
    'interval': 0.35,  
    "on-connect": on_connect,
    "on-release": on_release,
    'beep-on-connect': False,
}


def read_tag(clf, rdwr_options=rdwr_options):
    root.after(100, read_tag, clf)  # keep calling 'read_tag' every 100mS
    return clf.connect(rdwr=rdwr_options)


if __name__ == '__main__':
    with nfc.ContactlessFrontend() as clf:
        if not clf.open('usb:072f:2200'):
            raise RuntimeError('Failed to open NFC device.')
        else:
            ret = read_tag(clf)  # start calling 'read_tag'