We Keep Coding

display not changing despite variables being changed on tkinter

I want to write a program where after a user enters text and clicks a button, the text becomes a label and the button text is changed. My code is:
# Imports
import os, sys
import tkinter
"""
Tkinter program 1
text box + button + label
"""
# Button Entry
def enter(inputtedinfo, randvar, EnterMessage):
randvar = inputtedinfo.get()
EnterMessage = "Submitted!"
# Main Function
def main():
something = tkinter.Tk()
something.title("My First Tkinter Window")
something.geometry("600x400")
randvar = ""
EnterMessage = "Enter"
inputtedinfo = tkinter.StringVar()
userLabel = tkinter.Label(something, text = randvar)
userEntry = tkinter.Entry(something, textvariable = inputtedinfo)
userButton = tkinter.Button(something, text = EnterMessage, command = enter(inputtedinfo, randvar, EnterMessage))
userEntry.grid(row=0,column=0)
userLabel.grid(row=0,column=1)
userButton.grid(row=0,column=2)
something.mainloop()
sys.exit(0)
if(__name__ == "__main__"):
main()
The user input works, but clicking the button does nothing despite the fact that it is supposed to change the variables for the button and label displays. Did I mess up somewhere?

The command argument takes the name of a function. If you write the complete call with arguments, it's not the name of the function but whatever is returned by this exact function call. So, your button will not work. It will have the command None.
In order to do what you want to do, you have to make the StringVar()s accessible to the function you are calling. So, you can both get the contents of the entry and change the values of the button and the label. To do this, best add the string variables and the widgets as attributes to the toplevel you already created (something). So, they stay available to all functions and you can get and change information:
# Button Entry
def enter():
something.randvar.set(something.inputtedinfo.get())
something.userButton["text"] = "Submitted!"
# Main Function
def main():
global something
something = tkinter.Tk()
something.title("My First Tkinter Window")
something.geometry("600x400")
something.randvar = tkinter.StringVar()
something.randvar.set("")
EnterMessage = "Enter"
something.inputtedinfo = tkinter.StringVar()
userLabel = tkinter.Label(something, textvariable = something.randvar)
something.userEntry = tkinter.Entry(something, textvariable = something.inputtedinfo)
something.userButton = tkinter.Button(something, text = EnterMessage, command = enter)
something.userEntry.grid(row=0,column=0)
userLabel.grid(row=0,column=1)
something.userButton.grid(row=0,column=2)
something.mainloop()
if(__name__ == "__main__"):
main()

There are few issues in your code:
assign string to textvariable, should use StringVar instead
command=enter(...) will execute enter(...) immediately and then assign None to command option, should use lambda instead
updating strings inside enter() does not automatically update the label and the button, should use .set() on the StirngVar instead
Below is modified code:
def enter(inputtedinfo, randvar, EnterMessage):
# used .set() to update StringVar
randvar.set(inputtedinfo.get())
EnterMessage.set("Submitted!")
def main():
something = tkinter.Tk()
something.title("My First Tkinter Window")
something.geometry("600x400")
randvar = tkinter.StringVar() # changed to StringVar()
EnterMessage = tkinter.StringVar(value="Enter") # changed to StringVar()
inputtedinfo = tkinter.StringVar()
userLabel = tkinter.Label(something, textvariable=randvar) # used textvariable instead of text option
userEntry = tkinter.Entry(something, textvariable=inputtedinfo)
userButton = tkinter.Button(something, textvariable=EnterMessage, command=lambda: enter(inputtedinfo, randvar, EnterMessage))
userEntry.grid(row=0,column=0)
userLabel.grid(row=0,column=1)
userButton.grid(row=0,column=2)
something.mainloop()

Why is my threaded process still freezing?

I'm writing an app using tkinter for the GUI, and I want an indeterminate progress bar to be going back and forth while the main function is running, which sometimes takes a few seconds, depending on user input. Normally, the whole program freeze while the main function is running, so I am trying to establish a threaded process for the progress bar so it moves while main() is doing its thing (both functions are called withinscan_and_display()).
from tkinter import filedialog
from tkinter import *
from tkinter.ttk import Progressbar
from main import main
import graphs
from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg
from PIL import ImageTk, Image
import threading
root = Tk()
launch_frame = Frame(root)
button_frame = Frame(root)
graph_frame = Frame(root, height=1000, width=1200)
# log directory button/text
logDirButton = Button(master=launch_frame, text='Select log storage location...',
command=lambda: get_directory(log_text), width=22)
log_text = Text(master=launch_frame, height=1, width=25)
logDirButton.grid(row=1, column=0)
log_text.grid(row=1, column=1)
# scan directory button/text
dirButton = Button(master=launch_frame, text="Select scan directory...", command=lambda: get_directory(t), width=22)
t = Text(master=launch_frame, height=1, width=25)
dirButton.grid(row=2, column=0)
t.grid(row=2, column=1)
# main scan button
mainButton = Button(master=launch_frame, text="SCAN!", state=DISABLED,
width=50, height=10, bg='#27b355')
mainButton.grid(row=3, column=0, columnspan=2)
# progress bar
progress = Progressbar(launch_frame, orient=HORIZONTAL, length=100, mode='indeterminate')
progress.grid(row=4, column=0, columnspan=2)
launch_frame.grid(row=0, column=0, sticky=NW)
def get_directory(text):
# first clear form if it already has text
try:
text.delete("1.0", END)
except AttributeError:
pass
directory = filedialog.askdirectory()
# store the first directory for later specific reference
text.insert(END, directory)
# disable scan button until user has given necessary info to run (log storage location, scan directory)
enable_scan_button(log_text, t)
return directory
def enable_scan_button(logText, dirText):
if logText.get("1.0", END) != '\n' and dirText.get('1.0', END) != '\n':
mainButton['state'] = NORMAL
mainButton['command'] = lambda: scan_and_display()
else:
mainButton['state'] = DISABLED
def scan_and_display():
threading.Thread(target=bar_start).start()
# get scan directory and log directory from text fields
log_directory = log_text.get("1.0", END)[:-1]
scan_directory = t.get("1.0", END)[:-1]
# store the initial scan directory for later reference
top_dir = scan_directory
# runs the main scan function. Passes scan_directory and log_directory arguments
data, scanDate = main(log_directory, scan_directory)
display(scan_directory, data, scanDate, top_dir)
def bar_start():
print("BAR START CALLED")
progress.start(10)
With this setup (and various other configurations I've trieD), the bar still freezes while main() is doing it's thing, and I need it to move to indicate to the user that something is happening.

You need to thread the long-running function, not the progressbar.
def scan_and_display():
# get scan directory and log directory from text fields
# It's best to do all tkinter calls in the main thread
log_directory = log_text.get("1.0", END)[:-1]
scan_directory = t.get("1.0", END)[:-1]
th = threading.Thread(target=bar_start, args=(log_directory, scan_directory))
th.start()
progress.start()
def bar_start(log_directory, scan_directory):
print("BAR START CALLED")
# store the initial scan directory for later reference
top_dir = scan_directory
# runs the main scan function. Passes scan_directory and log_directory arguments
data, scanDate = main(log_directory, scan_directory)
display(scan_directory, data, scanDate, top_dir)
progress.stop()
EDIT: here's a MCVE:
import tkinter as tk
from tkinter.ttk import Progressbar
import time
from threading import Thread
def long_running_function(arg1, arg2, result_obj):
"""accept some type of object to store the result in"""
time.sleep(3) # long running function
result_obj.append(f'DONE at {int(time.time())}')
root.event_generate("<<LongRunningFunctionDone>>") # trigger GUI event
def long_func_start():
x = 'spam'
y = 'eggs'
t = Thread(target=long_running_function, args=(x,y,data))
t.start()
result.config(text='awaiting result')
progress.start()
def long_func_end(event=None):
progress.stop()
result.config(text=f"process finished with result:\n{data[-1]}")
root = tk.Tk()
root.geometry('200x200')
btn = tk.Button(root, text='start long function', command=long_func_start)
btn.pack()
progress = Progressbar(root, orient=tk.HORIZONTAL, length=100, mode='indeterminate')
progress.pack()
result = tk.Label(root, text='---')
result.pack()
root.bind("<<LongRunningFunctionDone>>", long_func_end) # tell GUI what to do when thread ends
data = [] # something to store data
root.mainloop()

Pass selection Listbox topwindow to main window

This is my first real Python project. I am currently developing a GUI in Tkinter that allows the user to select Tasks and CVs to automatically compile documents using standard predefined task and CV texts from a database.
I have created two "Add" buttons in the main window to add Tasks and CVs that show a popup Listbox that allow the user to select the Tasks and CVs they want to have included in the commercial proposal. I have managed to create the popup window as a separate Class and it stores the selected Tasks in a list, but now I need to pass the list with the selected items to the Listbox in the main window when the user clicks the Select button in the popup window, but I cannot get my head around on how to do that.
I have researched on different fora and watched a variety of Youtube videos, but all focus on entry popups or some sort.
This is the code for the main window:
from tkinter import *
from Add import *
# make main window
root = Tk()
theLabel = Label(root, text="ProposalBuilder")
theLabel.grid(row=0)
# make frames
taskFrame = Frame(root)
taskFrame.grid(row=1, column=0)
CVFrame = Frame(root)
CVFrame.grid(row=1, column=1)
buildFrame = Frame(root)
buildFrame.grid(row=2, columnspan=2)
# add labels to frames
taskLabel = Label(taskFrame, text="Tasks")
taskLabel.pack()
CVLabel = Label(CVFrame, text="CVs")
CVLabel.pack()
# add listboxes to frames
scrollTask = Scrollbar(taskFrame, orient=VERTICAL)
listTask = Listbox(taskFrame, selectmode=MULTIPLE, yscrollcommand=scrollTask.set)
scrollTask.config(command=listTask.yview)
scrollTask.pack(side=RIGHT, fill=Y)
listTask.pack()
scrollCV = Scrollbar(CVFrame, orient=VERTICAL)
listCV = Listbox(CVFrame, selectmode=MULTIPLE, yscrollcommand=scrollCV.set)
scrollCV.config(command=listCV.yview)
scrollCV.pack(side=RIGHT, fill=Y)
listCV.pack()
# add commands to buttons
def addTask():
taskBox = Add('C:\\Users\\204703\\ProposalBuilder\\Database')
sel_test = taskBox.selection
def addCV():
CVBox = Add('C:\\Users\\204703\\ProposalBuilder\\Database')
# add buttons to frames
buttonAddTask = Button(taskFrame, text="Add", command=addTask)
buttonAddTask.pack(fill=X)
buttonDelTask = Button(taskFrame, text="Delete")
buttonDelTask.pack(fill=X)
buttonUpTask = Button(taskFrame, text="Up")
buttonUpTask.pack(fill=X)
buttonDownTask = Button(taskFrame, text="Down")
buttonDownTask.pack(fill=X)
buttonAddCV = Button(CVFrame, text="Add", command=addCV)
buttonAddCV.pack(fill=X)
buttonDelCV = Button(CVFrame, text="Delete")
buttonDelCV.pack(fill=X)
buttonUpCV = Button(CVFrame, text="Up")
buttonUpCV.pack(fill=X)
buttonDownCV = Button(CVFrame, text="Down")
buttonDownCV.pack(fill=X)
buttonBuild = Button(buildFrame, text="Build Proposal")
buttonBuild.pack(side=RIGHT)
root.mainloop()
This is the code for the separate class I created for the popup window:
from tkinter import*
from os import *
class Add:
def __init__(self, path):
# the slected tasks
self.selection = []
# make a frame
top = Toplevel()
# get file names from the directory (path) and save in list
self.path = path
self.dirList = listdir(self.path)
# add listbox to frames and populate with file names
self.scrollList = Scrollbar(top, orient=VERTICAL)
self.listbox = Listbox(top, selectmode=MULTIPLE, yscrollcommand=self.scrollList.set)
self.scrollList.config(command=self.listbox.yview)
self.scrollList.pack(side=RIGHT, fill=Y)
for item in self.dirList:
self.listbox.insert(END,item)
self.listbox.pack()
# add buttons to frame
self.selectButton = Button(top, text="Select", command=self.select)
self.selectButton.pack()
self.quitButton = Button(top, text="Quit", command=top.destroy)
self.quitButton.pack()
# identify selected rows and return a list with the selection
def select(self):
selectedRows = self.listbox.curselection()
for item in selectedRows:
self.selection.append(self.dirList[item])
print(self.selection)
return self.selection

Question: pass the list with the selected items to the Listbox in the main window
You need a reference of the main window Listbox.
I show, how to using listTask
Extend your __init__ to accept the reference target_listbox
class Add:
def __init__(self, target_listbox, path):
self.target_listbox = target_listbox
Insert the selected items into .target_listbox
Note: Your, return self.selection is useless, a Button.command can't process returns.
def select(self):
selectedRows = self.listbox.curselection()
for item in selectedRows:
self.target_listbox.insert(tk.END, self.dirList[item])
Pass the reference listTask to Add(...
taskBox = Add(listTask, ...)

Tkinter: Calling function when button is pressed

import tkinter as tk
def load(event):
file = open(textField.GetValue())
txt.SetValue(file.read())
file.close()
def save(event):
file = open(textField.GetValue(), 'w')
file.write(txt.GetValue())
file.close()
win = tk.Tk()
win.title('Text Editor')
win.geometry('500x500')
# create text field
textField = tk.Entry(win, width = 50)
textField.pack(fill = tk.NONE, side = tk.TOP)
# create button to open file
openBtn = tk.Button(win, text = 'Open', command = load())
openBtn.pack(expand = tk.FALSE, fill = tk.X, side = tk.TOP)
# create button to save file
saveBtn = tk.Button(win, text = 'Save', command = save())
saveBtn.pack(expand = tk.FALSE, fill = tk.X, side = tk.TOP)
I get the error that load and save are missing a position argument: event. I understand the error, but don't understand how to resolve it.

Here's a runnable answer. In addition to changing the commmand= keyword argument so it doesn't call the function when the tk.Buttons are created, I also removed the event argument from the corresponding function definitions since tkinter doesn't pass any arguments to widget command functions (and your function don't need it, anyway).
You seem to be confusing event handlers with widget command function handlers. The former do have an event argument passed to them when they're called, but the latter typically don't (unless you do additional stuff to make it happen—it's a fairly common thing to need/want to do and is sometimes referred to as theThe extra arguments trick).
import tkinter as tk
# added only to define required global variable "txt"
class Txt(object):
def SetValue(data): pass
def GetValue(): pass
txt = Txt()
####
def load():
with open(textField.get()) as file:
txt.SetValue(file.read())
def save():
with open(textField.get(), 'w') as file:
file.write(txt.GetValue())
win = tk.Tk()
win.title('Text Editor')
win.geometry('500x500')
# create text field
textField = tk.Entry(win, width=50)
textField.pack(fill=tk.NONE, side=tk.TOP)
# create button to open file
openBtn = tk.Button(win, text='Open', command=load)
openBtn.pack(expand=tk.FALSE, fill=tk.X, side=tk.TOP)
# create button to save file
saveBtn = tk.Button(win, text='Save', command=save)
saveBtn.pack(expand=tk.FALSE, fill=tk.X, side=tk.TOP)
win.mainloop()

Remove the 'event' arguments from both function defs and remove brackets from your commands.

Use button.bind() mehtod and pass 'Button-1' in first argument and function name in second argument
def functionname(event):
#your code
button = tk.Button(win, text="Login", bg="green")#, command=attempt_log_in)
button.grid(row=5, column=2)
button.bind('<Button-1>', functionname)

You have functions save and load that takes 1 argument : event but when you called
# create button to open file
openBtn = tk.Button(win, text = 'Open', command = **load()**) <<<--- no argument in load
<<<---should be load(someEvent)
openBtn.pack(expand = tk.FALSE, fill = tk.X, side = tk.TOP)
# create button to save file
saveBtn = tk.Button(win, text = 'Save', command = **save()**)<<< ---- same for the save
saveBtn.pack(expand = tk.FALSE, fill = tk.X, side = tk.TOP)
But in your function save and load the argument : event you don't do nothing with it so you can just delete the event argument and this problem shouldn't appear. Like this :
def load():
file = open(textField.GetValue())
txt.SetValue(file.read())
file.close()
def save():
file = open(textField.GetValue(), 'w')
file.write(txt.GetValue())
file.close()

Python / Tkinter status bar not updating correctly

I have developed a simple app in Python (2.7) with Tkinter. But my status bar is only sort of working. Here's the stripped down code:
from Tkinter import *
import os
import sys
def fixFiles():
inputFilePath= input_dir.get()
#Build a list of files in a directory
fileList = os.listdir(inputFilePath)
#Loop through those files, open the file, do something, close the file
for filename in fileList:
infile = open(inputfilepath + "/" + filename,'r')
#Update the status with the filename
status_string = 'Status: Working on file: ' + str(filename)
status.set(status_string)
for line in infile:
#Do some stuff here
infile.close()
class App:
def __init__(self, master):
i = 0
status.set("Status: Press 'Fix Files!'")
statuslabel = Label(master, textvariable=status, relief = RIDGE, width = 65, pady = 5, anchor=W)
bFixFiles = Button(root, text='Fix Files!', command = fixFiles)
bQuit = Button(root, text='Quit', command = root.destroy)
statuslabel.grid(row=i, column = 0, columnspan = 2)
bFixFiles.grid(row=i, column=2, sticky=E)
bQuit.grid(row=i, column=3, sticky=W)
root = Tk()
root.title("FIX Files")
input_dir = StringVar()
status = StringVar()
choice = IntVar()
app = App(root)
root.mainloop()
Currently what's happening is that the status bar reads "Status: Press 'Fix Files!'" until the program is finished looping through the files, at which point it reads "Status: Working on file: XXXXX.txt" (which is the name of the last file to be opened and closed by the program.
I would like the status bar to update with the file name each time the program opens a new file. Any help is appreciated!

The goofy way is to use root.update_idletasks():
#Update the status with the filename
status_string = 'Status: Working on file: ' + str(filename)
status.set(status_string)
root.update_idletasks()
To its credit, it is simple, but it does not really work -- although the statuslabel gets updated, the Quit button is frozen until fixFiles is completed. That's not very GUI-friendly. Here are some more reasons why update and update_idletasks are considered harmful.
So how should we run a long-running task without freezing the GUI?
The key is to make your callback functions end quickly. Instead of having a long-running for-loop, make a function that runs through the innards of the for-loop once. Hopefully that ends quickly enough for the user to not feel the GUI has been frozen.
Then, to replace the for-loop, you could use calls to root.after to call your quick-running function multiple times.
from Tkinter import *
import tkFileDialog
import os
import sys
import time
def startFixFiles():
inputFilePath = tkFileDialog.askdirectory()
# inputFilePath= input_dir.get()
# Build a list of files in a directory
fileList = os.listdir(inputFilePath)
def fixFiles():
try:
filename = fileList.pop()
except IndexError:
return
try:
with open(os.path.join(inputFilePath, filename), 'r') as infile:
# Update the status with the filename
status_string = 'Status: Working on file: ' + str(filename)
status.set(status_string)
for line in infile:
# Do some stuff here
pass
except IOError:
# You might get here if file is unreadable, you don't have read permission,
# or the file might be a directory...
pass
root.after(250, fixFiles)
root.after(10, fixFiles)
class App:
def __init__(self, master):
i = 0
status.set("Status: Press 'Fix Files!'")
statuslabel = Label(
master, textvariable=status, relief=RIDGE, width=65,
pady=5, anchor=W)
bFixFiles = Button(root, text='Fix Files!', command=startFixFiles)
bQuit = Button(root, text='Quit', command=root.destroy)
statuslabel.grid(row=i, column=0, columnspan=2)
bFixFiles.grid(row=i, column=2, sticky=E)
bQuit.grid(row=i, column=3, sticky=W)
root = Tk()
root.title("FIX Files")
input_dir = StringVar()
status = StringVar()
choice = IntVar()
app = App(root)
root.mainloop()
The above begs the question, What should we do if our long-running task has no loop? or if even one pass through the loop requires a long time?
Here is a way to run the long-running task in a separate process (or thread), and have it communicate information through a queue which the main process can periodically poll (using root.after) to update the GUI status bar. I think this design is more easily applicable to this problem in general since it does not require you to break apart the for-loop.
Note carefully that all Tkinter GUI-related function calls must occur from a single thread. That is why the long-running process simply sends strings through the queue instead of trying to call status.set directly.
import Tkinter as tk
import multiprocessing as mp
import tkFileDialog
import os
import Queue
sentinel = None
def long_running_worker(inputFilePath, outqueue):
# Build a list of files in a directory
fileList = os.listdir(inputFilePath)
for filename in fileList:
try:
with open(os.path.join(inputFilePath, filename), 'r') as infile:
# Update the status with the filename
status_string = 'Status: Working on file: ' + str(filename)
outqueue.put(status_string)
for line in infile:
# Do some stuff here
pass
except IOError:
# You might get here if file is unreadable, you don't have read permission,
# or the file might be a directory...
pass
# Put the sentinel in the queue to tell update_status to end
outqueue.put(sentinel)
class App(object):
def __init__(self, master):
self.status = tk.StringVar()
self.status.set("Status: Press 'Fix Files!'")
self.statuslabel = tk.Label(
master, textvariable=self.status, relief=tk.RIDGE, width=65,
pady=5, anchor='w')
bFixFiles = tk.Button(root, text='Fix Files!', command=self.startFixFiles)
bQuit = tk.Button(root, text='Quit', command=root.destroy)
self.statuslabel.grid(row=1, column=0, columnspan=2)
bFixFiles.grid(row=0, column=0, sticky='e')
bQuit.grid(row=0, column=1, sticky='e')
def update_status(self, outqueue):
try:
status_string = outqueue.get_nowait()
if status_string is not sentinel:
self.status.set(status_string)
root.after(250, self.update_status, outqueue)
else:
# By not calling root.after here, we allow update_status to truly end
pass
except Queue.Empty:
root.after(250, self.update_status, outqueue)
def startFixFiles(self):
inputFilePath = tkFileDialog.askdirectory()
# Start long running process
outqueue = mp.Queue()
proc = mp.Process(target=long_running_worker, args=(inputFilePath, outqueue))
proc.daemon = True
proc.start()
# Start a function to check a queue for GUI-related updates
root.after(250, self.update_status, outqueue)
root = tk.Tk()
root.title("FIX Files")
app = App(root)
root.mainloop()