Python Logging to Tkinter Text Widget

Question

Does any one out there have an example of how to setup logging in Python to a Tkinter Text Widget? I have seen this used in several apps but cannot figure out how to direct

Answer 1

I've bumped the same problem. The common solution found was like mentioned in this thread- bringing widget from GUI module to Logging.Handler.
It was criticized as not safety, as a widget is passes to another thread (logging).
The best solution found was using queue, made by Benjamin Bertrand: https://beenje.github.io/blog/posts/logging-to-a-tkinter-scrolledtext-widget/.
I improved it a bit: queue should be created in logging handler, and passed to a GUI widget.

import logger
import queue


class QueueHandler(logging.Handler):
    def __init__(self):
        super().__init__()
        self.log_queue = queue.Queue()

    def emit(self, record):
        # put a formatted message to queue
        self.log_queue.put(self.format(record))


queue_handler = QueueHandler()
logger.addHandler(queue_handler)

So we have generally available logger, and every log message from any module will be passed to a queue_handler along with other handlers - to a file etc. Now we can import queue_handler to a widget.
Most of the code is taken from the link above, I just changed the location of the original logging queue.

from tkinter.scrolledtext import ScrolledText
from  some_logging_module import queue_handler

class ConsoleUi:
    """Poll messages from a logging queue and display them in a scrolled text widget"""

    def __init__(self, frame, queue):
        self.frame = frame
        # Create a ScrolledText wdiget
        self.console = ScrolledText(frame)
        self.console.configure(font='TkFixedFont')
        self.console.pack(padx=10, pady=10, fill=BOTH, expand=True)
        self.log_queue = queue
        # Start polling messages from the queue
        self.frame.after(100, self.poll_log_queue)

    def display(self, msg):
        self.console.configure(state='normal')
        self.console.insert(END, msg + '\n')
        self.console.configure(state='disabled')
        # Autoscroll to the bottom
        self.console.yview(END)

    def poll_log_queue(self):
        # Check every 100ms if there is a new message in the queue to display
        while not self.log_queue.empty():
            msg = self.log_queue.get(block=False)
            self.display(msg)
        self.frame.after(100, self.poll_log_queue)

As result a widget displays all logging data of an app.