Develop Reference

How to insert a char instead of another in Tkinter Entry with validatecommand?

Starting my adventure with python Tkinter I just tried to develop an Entry which accepts only dates. However, more than just validate the Entry I was trying to coordinate the content "appearance" by adding "/" in proper positions to have a valid date format (dd/mm/aaaa). The problem is: if I insert a char instead of another, using the Entry method or StringVar, the validate function just work no longer for any other insert in the Entry.
What is the problem with that solution?
Is there a way to make it work?
Here is the code I was developing:
from tkinter import *
root = Tk()
def f(att):
print(att)
if len(att) == 0:
return True
elif len(att) == 1 and att in "123":
return True
elif len(att) == 2 and att.isdigit() and int(att) < 32:
return True
elif len(att) == 3 and att[-1] != "/":
ent.insert(END, "/")
return True
else:
return False
ent = Entry(root, validate="key")
ent["validatecommand"] = (ent.register(f), "%P")
ent.pack(pady=10, padx=10)
ent.focus()
root.mainloop()

Cannot get value from Radiobutton

When I run this code:
currentquestion = 0
currentcheckbox = 1
which_radio_var = StringVar(inside_test_root)
while currentquestion < len(questions):
print('currentcheckbox', currentcheckbox)
Radiobutton(inside_test_root, text=questions[currentquestion], value=currentcheckbox, variable=which_radio_var, indicatoron=0, wraplength=30).grid(row=currentquestion+1, column=0)
currentquestion += 2
currentcheckbox += 1
x = which_radio_var.get()
I get the Radiobuttons coming up fine and everything works properly, apart from wen I try to test these radiobuttons with the code:
Button(inside_test_root, text='oof', command=print(x)).grid(column = 77, row = 77)
Nothing prints. Is it something to do with the nature i made the radiobuttons? I need a way to not know the amount of buttons that are being produced beforehand.
Any help would be much appreciated, thanks

Answer is as jasonharper said, I missed out the lambda, meaning that i was calling the print function the first time and never again
"command=print(x) means to print x right now, and use the return value of the print() function (which is None) as the command to execute when the button is clicked. command=lambda: print(which_radio_var.get()) would do the job. "
Updated code is now: (the variable 'x' has become 'radio' to fit with the rest of my program)
if questiontype == 'Multiple Choice':
currentquestion = 0
currentcheckbox = 1
which_radio_var = StringVar(inside_test_root)
print (which_radio_var)
while currentquestion < len(questions):
print('currentcheckbox', currentcheckbox)
Radiobutton(inside_test_root, text=questions[currentquestion], value=currentcheckbox, variable=which_radio_var, indicatoron=0, wraplength=30).grid(row=currentquestion+1, column=0)
currentquestion += 2
currentcheckbox += 1
print(which_radio_var.get())
radio = which_radio_var.get()
Button(inside_test_root, text='oof', command=lambda: print(radio)).grid(column = 77, row = 77)

Compare tkinter Entry to actual addition answer

I'm trying to compare the input of an Entry box to the actual answer. This is one of my first python projects and I'm still very confused and to be honest I don't even know how to start asking the question.
The user will click either the addition or subtraction button. A string will appear asking "What does 4 + 5 equal?" The numbers are generated randomly.
I then insert an Entry box using the tkinter library. I don't know how to get() the input and compare it to the sum or difference of the actual numbers.
I was trying to follow this video but I've failed using other methods as well. FYI, I was focusing on the addition method mostly so if you test, that with addition first.
from tkinter import Entry
import tkinter as tk
import random as rand
root = tk.Tk()
root.geometry("450x450+500+300")
root.title("Let's play Math!")
welcomeLabel = tk.Label(text="LET'S PLAY MATH!").pack()
startLabel = tk.Label(text='Select a math operation to start').pack()
def addition():
a = rand.randrange(1,10,1)
b = rand.randrange(1,10,1)
global Answer
Answer = a + b
tk.Label(text="What does " + str(a) + " + " + str(b) + " equal? ").place(x=0, y=125)
global myAnswer
myAnswer = Entry().place(x=300, y= 125)
def checkAnswer():
entry = myAnswer.get()
while int(entry) != Answer:
if int(entry) != Answer:
tk.Label(text="Let's try again.").pack()
elif int(entry) == Answer:
tk.Label(text="Hooray!").pack()
addBtn = tk.Button(text="Addition", command=addition).place(x=100, y = 60)
subBtn = tk.Button(text="Subtraction", command=subtraction).place(x=200, y=60)
checkBtn = tk.Button(text="Check Answer", command=checkAnswer).place(x=300, y = 150)
tk.mainloop()

All you need to do to fix your issue is separate the creation of your Entry() object from the placing of it:
def addition():
a = rand.randrange(1,10,1)
b = rand.randrange(1,10,1)
global Answer
Answer = int(a + b)
tk.Label(text="What does " + str(a) + " + " + str(b) + " equal? ").place(x=0, y=125)
global myAnswer
myAnswer = Entry()
myAnswer.place(x=300, y= 125)
Entry() returns the entry object, which has a get() method. However, when you chain .place(), you return its result instead, which is None. Therefore you never actually store the Entry object in your variable.
Also, it is a good idea to ensure that Answer is an int as well.

to get the value of the answer do answer = myanswer.get() or any other variable name. To compare it to the correct answer do
if int(answer) == correctAnswer:
#the code
is that what you were asking?

Consider this and below is an example that responds to whether or not the number entered to answer is "Correct!" or "False!" when the user clicks on answer_btn:
import tkinter as tk
import random as rand
def is_correct():
global answer, check
if answer.get() == str(a + b):
check['text'] = "Correct!"
else:
check['text'] = "False!"
def restart():
global question, check
random_nums()
question['text'] = "{}+{}".format(a, b)
check['text'] = "Please answer the question!"
def random_nums():
global a, b
a = rand.randrange(1, 10, 1)
b = rand.randrange(1, 10, 1)
root = tk.Tk()
#create widgets
question = tk.Label(root)
answer = tk.Entry(root, width=3, justify='center')
check = tk.Label(root)
tk.Button(root, text="Check", command=is_correct).pack()
tk.Button(root, text="New question", command=restart).pack()
#layout widgets
question.pack()
answer.pack()
check.pack()
restart()
root.mainloop()

TkInter Entry Box Being Disabled

I'm working on a GUI Python program using Tkinter.
I have a function that is called when a button is pressed (and when the program is loaded). The program is currently unfinished and only checks data validation at this current point. As the default entry is current invalid, it throws an error.
However, after this point, the entry box is disabled and will not let me enter any data. I cannot figure out why this is happening and I was wondering if someone could tell me the reason so I can work on a solution.
Thanks
import sys
import random
from tkinter import *
from tkinter import ttk
from tkinter import messagebox
root = Tk()
root.title("COSC110 - Guessing Game")
hint = StringVar()
guesses = []
guess_input = ''
def loadWordList(filename): #Load the words from a file into a list given a filename.
file = open(filename, 'r')
line = file.read().lower()
wordlist = line.split()
return wordlist
word = random.choice(loadWordList('words.txt'))
def getHint(word, guesses): #Get hint function, calculates and returns the current hint.
hint = ' '
for letter in word:
if letter not in guesses:
hint += '_ '
else:
hint += letter
return hint
def guessButton(guess, word, guesses):
guess = str(guess_input)
guess = guess.lower()
if not guess.isalpha():
is_valid = False
elif len(guess) !=1:
is_valid = False
else:
is_valid = True
while is_valid == False:
messagebox.showinfo("Error:","Invalid input. Please enter a letter from a-z.")
break
hint.set(getHint(word, guesses))
return hint
label_instruct = Label(root, text="Please enter your guess: ")
label_instruct.grid(row=1,column=1,padx=5,pady=10)
guess_input = Entry(root,textvariable=guess_input)
guess_input.grid(row=1, column=2)
guess_button = Button(root, text="Guess", width=15, command=guessButton(guess_input,word,guesses))
guess_button.grid(row=1, column=3,padx=15)
current_hint = Label(root, textvariable=hint)
current_hint.grid(column=2,row=2)
label_hint = Label(root, text="Current hint:")
label_hint.grid(column=1,row=2)
label_remaining = Label(root, text="Remaining guesses: ")
label_remaining.grid(column=1,row=3)
root.mainloop() # the window is now displayed
Any tips are appreciated.

There are two apparent problems.
Firstly, you shouldn't use
guess_button = Button(root, text="Guess", width=15, command=guessButton(guess_input,word,guesses))
because you can't call a function with arguments on the command config.
My suggestion would be to take a look here and use one of the proposed methods, I particularly like the one using functools and partial:
from functools import partial
#(...)
button = Tk.Button(master=frame, text='press', command=partial(action, arg))
with action being the function you want to call and arg the parameters you want to call separated by a comma.
Secondly, you are using
guess = str(guess_input)
which doesn't return the Entry typed text, use instead
guess = guess_input.get()
PS: Albeit not directly related to your question, you should use
if var is False:
instead of
if var == False:

Separating Tkinter UI concerns from Logic in Python app

This is my first app ever. It is working well but I would like to separate the UI concerns like getting input and creating labels, from the translation logic. I would then like to remove the output from the previous translation, i.e., only showing one translation on the screen at a time.
How can I separate the translation logic from my Tkinter GUI?
from Tkinter import *
import tkMessageBox
def start():
inputg = input.get()
if len(inputg) >= 2 and inputg.isalpha():
new_word_out = Label(text=(inputg[1:] + (inputg[0] + "ay")).lower().title()).pack()
out_message = Label(text="Cool! Try another!").pack()
# restart()
elif len(inputg) <= 1 and inputg.isalpha():
show_error(message="Whoops! I need 2 or more characters to translate! Try again!")
return
elif len(inputg) >= 1 and not inputg.isalpha():
show_error(message="Whoops! No numbers or symbols please! Try again!")
return
elif len(inputg) == 0:
show_error(message="It seems you haven't given me anything to translate!")
return
def show_error(message):
tkMessageBox.showerror(title="Error", message=message)
return
def quit():
ask_exit = tkMessageBox.askyesno(title="Quit", message="Are you sure you want to quit?")
if ask_exit > 0:
root.destroy()
return
root = Tk()
input = StringVar() # stores user input into this variable as a string.
root.title("The Pig Translator")
root.protocol("WM_DELETE_WINDOW", quit)
labeltitle1 = Label(text="Hello there! This is my Pig Latin Translator!").pack()
labeltitle2 = Label(text="Please enter a word to continue!", fg='darkgreen', bg='grey').pack()
original_entry = Entry(textvariable=input, bd=5, fg='darkgreen').pack()
translate_button = Button(text="Translate", command=start).pack()
root.bind('<Return>', lambda event: start()) # essentially binds 'Return' keyboard event to translate_button
root.mainloop()

There are many ways you can separate logic from GUI. generally I would recommend using classes and callback functions. Thus, I made a class that generates the gui. However, the translation is performed by external function called do_translation.
MyFrame does not know much about how do_translation. It only knows it returns translated_str, message and takes string as argument. do_translation does not relay on any gui as well. The do_translation takes only an input string, does what it wants, and returns translated string and message. The MyFrame take this function as a callback. You can make any other translation function, and as long as the input and output are same, it will work.
I rely here on a "Cool" in a massage which indicates that translation was ok. Its poor idea to make it relay on 'Cool' word, but did not want to change your code too much. Probably better to raise some error, or use message codes, etc.
from Tkinter import *
import tkMessageBox
class MyFrame(Frame):
def __init__(self, master, input_callback=None, **kwargs):
Frame.__init__(self, master)
self.set_input_callback(input_callback)
self.create_widgets()
self.pack()
def create_widgets(self):
self.input = StringVar() # stores user input into this variable as a string.
self.labeltitle1 = Label(text="Hello there! This is my Pig Latin Translator!")
self.labeltitle1.pack()
self.labeltitle2 = Label(text="Please enter a word to continue!", fg='darkgreen', bg='grey')
self.labeltitle2.pack()
self.original_entry = Entry(textvariable=self.input, bd=5, fg='darkgreen')
self.original_entry.pack()
self.translate_button = Button(text="Translate", command=self.start)
self.translate_button.pack()
self.new_word_out = Label(text='')
self.out_message = Label(text='')
def set_input_callback(self, some_fun):
self.input_callback = some_fun
def show_error(self, message):
tkMessageBox.showerror(title="Error", message=message)
return
def start(self):
inputg = self.input.get()
if self.input_callback:
translated_str, message = self.input_callback(inputg)
if 'Cool' in message:
self.new_word_out['text'] = translated_str
self.new_word_out.pack()
self.out_message['text'] = message
self.out_message.pack()
else:
self.show_error(message)
def do_translation(inputg):
translated_str = message = ''
if len(inputg) >= 2 and inputg.isalpha():
translated_str = (inputg[1:] + (inputg[0] + "ay")).lower()
message = "Cool! Try another!"
elif len(inputg) <= 1 and inputg.isalpha():
message = "Whoops! I need 2 or more characters to translate! Try again!"
elif len(inputg) >= 1 and not inputg.isalpha():
message = "Whoops! No numbers or symbols please! Try again!"
elif len(inputg) == 0:
message = "It seems you haven't given me anything to translate!"
return translated_str, message
def quit():
ask_exit = tkMessageBox.askyesno(title="Quit", message="Are you sure you want to quit?")
if ask_exit > 0:
root.destroy()
return
root = Tk()
root.title("The Pig Translator")
root.protocol("WM_DELETE_WINDOW", quit)
mf = MyFrame(root)
mf.set_input_callback(do_translation)
root.bind('<Return>', lambda event: start()) # essentially binds 'Return' keyboard event to translate_button
root.mainloop()
Hopefully this will be useful. I know, that there is not too much explanation what is happening here, but, don't have much time to write it. Your problem is very general.