We Keep Coding

Tkinter - Python, how do I cause a button click to assign a value to a variable?

Using Tkinter and Python. Already created a window for the buttons to be placed on. I want there to be four buttons to appear, and I want to be able to click one of the four buttons, and be able for it to set the selection variable = "whatever I clicked", so that I can then use this variable later to call an API. When I run the program and click on the "General knowledge" button and print the selection, it does correctly print "General knowledge", but then when I try to return this selection variable it just doesn't work and I don't know why.
def select1():
selection = "General Knowledge"
print(selection)
def select2():
selection = "Science"
def select3():
selection = "Entertainment"
def select4():
selection = "Miscellaneous"
button1 = tk.Button(text = "General Knowledge", command = select1)
button1.place(x=100, y=100)
button2 = tk.Button(text = "Science", command = select2)
button2.place(x=100, y=140)
button3 = tk.Button(text = "Entertainment", command = select3)
button3.place(x=100, y=180)
button4 = tk.Button(text = "Miscellaneous", command = select4)
button4.place(x=100, y=220)

There are several ways to accomplish your goal.
One way is to write a single function that will take a value to assign to your variable. This way you can have as many buttons as you like and only a single function.
Not if you are using functions you have to either pass the variable to the function or let the function know it is in the global namespace.
import tkinter as tk
root = tk.Tk()
selection = ''
def assign_value(value):
global selection
selection = value
lbl["text"] = value
print(selection)
lbl = tk.Label(root, text='Selection Goes Here')
lbl.grid(row=0, column=0)
tk.Button(text="General Knowledge", command=lambda: assign_value("General Knowledge")).grid(row=1, column=0)
tk.Button(text="Science", command=lambda: assign_value("Science")).grid(row=2, column=0)
tk.Button(text="Entertainment", command=lambda: assign_value("Entertainment")).grid(row=3, column=0)
tk.Button(text="Miscellaneous", command=lambda: assign_value("Miscellaneous")).grid(row=4, column=0)
root.mainloop()
Or you can assign the value directly from the button.
import tkinter as tk
root = tk.Tk()
selection = tk.StringVar()
selection.set('Selection Goes Here')
lbl = tk.Label(root, textvariable=selection)
lbl.grid(row=0, column=0)
tk.Button(text="General Knowledge", command=lambda: selection.set("General Knowledge")).grid(row=1, column=0)
tk.Button(text="Science", command=lambda: selection.set("Science")).grid(row=2, column=0)
tk.Button(text="Entertainment", command=lambda: selection.set("Entertainment")).grid(row=3, column=0)
tk.Button(text="Miscellaneous", command=lambda: selection.set("Miscellaneous")).grid(row=4, column=0)
root.mainloop()
I am sure if I spent more time on this I could think up something else but the idea is basically write your code in a more DRY (Don't Repeat Yourself) fashion and make sure you are assigning the value to the variable in the global namespace or else it will not work as you expect.

How to get the text of Checkbuttons?

Checkbuttons gets generated dynamically and they are getting text from a python list.
I need a logic for capturing selected checkbuttons text .
As per my research everywhere they are returning the state of checkbox instead of text.
Please help.
cb_list =['pencil','pen','book','bag','watch','glasses','passport','clothes','shoes','cap']
try:
r = 0
cl = 1
for op in cb_list:
cb = Checkbutton(checkbutton_frame, text=op, relief=RIDGE)
cb.grid(row=r, column=cl, sticky="W")
r = r + 1
except Exception as e:
logging.basicConfig(filename=LOG_FILENAME, level=logging.ERROR)
logging.error(e)
# print (e)
selected_item = Text(self, width=30, height=20, wrap=WORD)
selected_item.grid(row=1, column=6, padx=20, pady=20, columnspan=2, sticky=E)
display_button = Button(self, text='DISPLAY', command=display()
convert_button.grid(row=1, column=8, padx=20, pady=20)

The idea is to associate one BooleanVar to each checkbutton and store them in a list cb_var. Then, to display the selected items, we just have to clear the display box (I have used a Listbox) and then loop simultaneously through cb_list and cb_var to determine which items are selected:
import tkinter as tk
root = tk.Tk()
checkbutton_frame = tk.Frame(root)
checkbutton_frame.grid(row=1, column=0)
def display():
# clear listbox
selected_item.delete(0, 'end')
# add selected items in listbox
for text, var in zip(cb_list, cb_var):
if var.get():
# the checkbutton is selected
selected_item.insert('end', text)
cb_list = ['pencil','pen','book','bag','watch','glasses','passport','clothes','shoes','cap']
cb_var = [] # to store the variables associated to the checkbuttons
cl = 1
for r, op in enumerate(cb_list):
var = tk.BooleanVar(root, False)
cb = tk.Checkbutton(checkbutton_frame, variable=var, text=op, relief='ridge')
cb.grid(row=r, column=cl, sticky="w")
cb_var.append(var)
selected_item = tk.Listbox(root, width=30, height=20)
selected_item.grid(row=1, column=6, padx=20, pady=20, columnspan=2, sticky='e')
display_button = tk.Button(root, text='DISPLAY', command=display)
display_button.grid(row=1, column=8, padx=20, pady=20)
root.mainloop()
EDIT: If you want to be able to change the list of items easily, you can use a function init_checkbuttons to create the checkbuttons from your list
of items. This function does the following things:
Destroy all previous checkbuttons
Clear the listbox
Create the new checkbuttons
Change the command of the display button
You can notice that the display function now takes cb_list and cb_var in argument, so that you can change them.
import tkinter as tk
root = tk.Tk()
checkbutton_frame = tk.Frame(root)
checkbutton_frame.grid(row=1, column=0)
def display(cb_list, cb_var):
# clear listbox
selected_item.delete(0, 'end')
# add selected items in listbox
for text, var in zip(cb_list, cb_var):
if var.get():
# the checkbutton is selected
selected_item.insert('end', text)
def init_checkbuttons(cb_list, cl=1):
# destroy previous checkbuttons (assuming that checkbutton_frame only contains the checkbuttons)
cbs = list(checkbutton_frame.children.values())
for cb in cbs:
cb.destroy()
# clear listbox
selected_item.delete(0, 'end')
# create new checkbuttons
cb_var = [] # to store the variables associated to the checkbuttons
for r, op in enumerate(cb_list):
var = tk.BooleanVar(root, False)
cb = tk.Checkbutton(checkbutton_frame, variable=var, text=op, relief='ridge')
cb.grid(row=r, column=cl, sticky="w")
cb_var.append(var)
# change display command
display_button.configure(command=lambda: display(cb_list, cb_var))
cb_list = ['pencil', 'pen', 'book', 'bag', 'watch', 'glasses', 'passport', 'clothes', 'shoes', 'cap']
cb_list2 = ['ball', 'table', 'bat']
selected_item = tk.Listbox(root, width=30, height=20)
selected_item.grid(row=1, column=6, padx=20, pady=20, columnspan=2, sticky='e')
display_button = tk.Button(root, text='DISPLAY')
display_button.grid(row=1, column=8, padx=20, pady=20)
tk.Button(root, text='Change list', command=lambda: init_checkbuttons(cb_list2)).grid(row=2, column=8)
init_checkbuttons(cb_list)
root.mainloop()

Instead of overwriting the same variable, cb, try using an iterable type such as dictionary. You should also need to be attaching the value of Checkbutton to a tkinter variable class, such as BooleanVar, in order to easily track its status & value.
The code below produces a GUI that re-writes Text each time a Checkbutton is selected. It first populates a dictionary, cbs, with items from a list, cb_list, as keys and tk.Checkbutton objects as the values.
Checkbutton objects are so that each is attached to a special object, Tkinter Variable class, BooleanVar, which has a get method that returns the Checkbutton it is attached to's current value when called. In this case, each Checkbutton holds True if checked, and False if unchecked as its value.
Each Checkbutton is also attached to a method, update_text, which is called when any of the Checkbutton is pressed. In that method for every Checkbutton in cbs, it first checks if the Checkbutton has True value, if so it appends its text to a _string. After this has been done for all Checkbuttons, the method then proceeds as first deleteing the entire text in the Text widget, then it puts _string to the Text.
The code:
import tkinter as tk
def update_text():
global cbs
_string = ''
for name, checkbutton in cbs.items():
if checkbutton.var.get():
_string += checkbutton['text'] + '\n'
text.delete('1.0', 'end')
text.insert('1.0', _string)
if __name__ == '__main__':
root = tk.Tk()
text = tk.Text(root)
cb_list =['pencil','pen','book','bag','watch','glasses','passport',
'clothes','shoes','cap']
cbs = dict()
for i, value in enumerate(cb_list):
cbs[value] = tk.Checkbutton(root, text=value, onvalue=True,
offvalue=False, command=update_text)
cbs[value].var = tk.BooleanVar(root, value=False)
cbs[value]['variable'] = cbs[value].var
cbs[value].grid(row=i, column=0)
text.grid()
root.mainloop()
text is an option to Checkbutton widget, which means you can get its value using cget(widget.cget('option')) or simply widget['option'].

Set Entry widget values dynamically in Tkinter

I have a window to browse a folder containing necessary files. I am using tkFileDialog for the same. I want to set the value of Entry widget equal to this selected folder. Initially when no folder is selected it will be null. As soon as I select the folder, the path of the selected folder should appear in the Entry widget. The user should be able to modify.Below mentioned is the code for the same.
from Tkinter import *
from tkFileDialog import *
class Checkit:
root = Tk()
#default string to be displayed in the entry of path
path_to_file = StringVar(root, value="abc")
def __init__(self):
self.inputDetail()
def inputDetail(self):
#copy the root window
master = self.root
#create frame for details in the root window
details_frame = Frame(master)
details_frame.grid(row=0, column=0)
#Create the Labels
papercode_label = Label(details_frame, text="Paper code:")
subject_label = Label(details_frame, text="Subject:")
chapter_label = Label(details_frame, text="Chapter:")
batch_label = Label(details_frame, text="Batch:")
ansFolder_label = Label(details_frame, text="Folder containing answer-keys:")
#create entry for the labels
papercode_entry = Entry(details_frame)
subject_entry = Entry(details_frame)
chapter_entry = Entry(details_frame)
batch_entry = Entry(details_frame)
ansFolder_entry = Entry(details_frame)
#create button to add path
path = Button(details_frame, text="Browse", command= lambda: self.addpath(details_frame))
#button to enter the next window
next = Button(details_frame, text="Next", command= lambda: self.checkOmr(details_frame, master))
#Use grid layout to place labels and entry
papercode_label.grid(row=0, sticky=W)
papercode_entry.grid(row=1, sticky=W)
subject_label.grid(row=2, sticky=W)
subject_entry.grid(row=3, column=0, sticky=W)
chapter_label.grid(row=4, sticky=W)
chapter_entry.grid(row=5, column=0, sticky=W)
batch_label.grid(row=6, sticky=W)
batch_entry.grid(row=7, column=0, sticky=W)
ansFolder_label.grid(row=8, sticky=W)
path.grid(row=9, sticky=W, columnspan=2)
next.grid(row=10, sticky=E, columnspan=2)
master.mainloop()
def checkOmr(self, old_frame, master):
#destoy the old frame
old_frame.destroy()
#create frame for details in the root window
inputPath_frame = Frame(master)
inputPath_frame.grid(row=0, column=0)
#create label to input folder containing
omrFolder_label = Label(inputPath_frame, text="Folder containing OMR sheet to be checked:")
#create button to add path
path = Button(inputPath_frame, text="Browse", command= lambda: self.addpath(inputPath_frame))
selected_path = Entry(inputPath_frame, textvariable=self.path_to_file)
#place the label and button on the grid
omrFolder_label.grid(row=0, sticky=W)
path.grid(row=1, column=0, sticky=W)
selected_path.grid(row=1, column=1, sticky=W)
#master.mainloop()
def addpath(self, details_frame):
self.path_to_file = askdirectory(parent=details_frame,initialdir="/",title='Please select a directory')
if __name__=='__main__':
handle = Checkit()
Here I am trying to change the modifying the self. path_to_file value on the click of the button. I tried to print the value of self.path_to_file value in addpath(). It gives correct result there but the value in the Entry selected_path in checkOMR() does not modify.
Can somebody suggest what changes should I make to make that thing possible.

Look at this line:
self.path_to_file = askdirectory(...)
Before this line of code runs, self.path_to_file is an instance of a StringVar. After this line of code has run, self.path_to_file is reset to be just a string.
Assuming you want self.path_to_file to remain an instance of StringVar, you need to change that line to this:
path = askdirectory(...)
self.path_to_file.set(path)

.get() not giving a value [duplicate]

I'm trying to use an Entry field to get manual input, and then work with that data.
All sources I've found claim I should use the get() function, but I haven't found a simple working mini example yet, and I can't get it to work.
I hope someone can tel me what I'm doing wrong. Here's a mini file:
from tkinter import *
master = Tk()
Label(master, text="Input: ").grid(row=0, sticky=W)
entry = Entry(master)
entry.grid(row=0, column=1)
content = entry.get()
print(content) # does not work
mainloop()
This gives me an Entry field I can type in, but I can't do anything with the data once it's typed in.
I suspect my code doesn't work because initially, entry is empty. But then how do I access input data once it has been typed in?

It looks like you may be confused as to when commands are run. In your example, you are calling the get method before the GUI has a chance to be displayed on the screen (which happens after you call mainloop.
Try adding a button that calls the get method. This is much easier if you write your application as a class. For example:
import tkinter as tk
class SampleApp(tk.Tk):
def __init__(self):
tk.Tk.__init__(self)
self.entry = tk.Entry(self)
self.button = tk.Button(self, text="Get", command=self.on_button)
self.button.pack()
self.entry.pack()
def on_button(self):
print(self.entry.get())
app = SampleApp()
app.mainloop()
Run the program, type into the entry widget, then click on the button.

You could also use a StringVar variable, even if it's not strictly necessary:
v = StringVar()
e = Entry(master, textvariable=v)
e.pack()
v.set("a default value")
s = v.get()
For more information, see this page on effbot.org.

A simple example without classes:
from tkinter import *
master = Tk()
# Create this method before you create the entry
def return_entry(en):
"""Gets and prints the content of the entry"""
content = entry.get()
print(content)
Label(master, text="Input: ").grid(row=0, sticky=W)
entry = Entry(master)
entry.grid(row=0, column=1)
# Connect the entry with the return button
entry.bind('<Return>', return_entry)
mainloop()

*
master = Tk()
entryb1 = StringVar
Label(master, text="Input: ").grid(row=0, sticky=W)
Entry(master, textvariable=entryb1).grid(row=1, column=1)
b1 = Button(master, text="continue", command=print_content)
b1.grid(row=2, column=1)
def print_content():
global entryb1
content = entryb1.get()
print(content)
master.mainloop()
What you did wrong was not put it inside a Define function then you hadn't used the .get function with the textvariable you had set.

you need to put a textvariable in it, so you can use set() and get() method :
var=StringVar()
x= Entry (root,textvariable=var)

Most of the answers I found only showed how to do it with tkinter as tk. This was a problem for me as my program was 300 lines long with tons of other labels and buttons, and I would have had to change a lot of it.
Here's a way to do it without importing tkinter as tk or using StringVars. I modified the original mini program by:
making it a class
adding a button and an extra method.
This program opens up a tkinter window with an entry box and an "Enter" button. Clicking the Enter button prints whatever is in the entry box.
from tkinter import *
class mini():
def __init__(self):
master = Tk()
Label(master, text="Input: ").grid(row=0, sticky=W)
Button(master, text='Enter', command=self.get_content).grid(row=1)
self.entry = Entry(master)
self.entry.grid(row=0, column=1)
master.mainloop()
def get_content(self):
content = self.entry.get()
print(content)
m = mini()

Tkinter. Press Enter in Entry box. Append to Text box. How?

I am making a chat program and decided to use Tkinter for the interface.
What I wanna do is a breeze in C# but Tkinter is new to me.
Basically I have a form with a Entry control and a Text control.
I want to know how to append text from the Entry control to the Text control after the user presses Enter.
Here's my code so far:
from tkinter import *
class Application:
def hello(self):
msg = tkinter.messagebox.askquestion('title','question')
def __init__(self, form):
form.resizable(0,0)
form.minsize(200, 200)
form.title('Top Level')
# Global Padding pady and padx
pad_x = 5
pad_y = 5
# create a toplevel menu
menubar = Menu(form)
#command= parameter missing.
menubar.add_command(label="Menu1")
#command= parameter missing.
menubar.add_command(label="Menu2")
#command= parameter missing.
menubar.add_command(label="Menu3")
# display the menu
form.config(menu=menubar)
# Create controls
label1 = Label(form, text="Label1")
textbox1 = Entry(form)
#command= parameter missing.
button1 = Button(form, text='Button1')
scrollbar1 = Scrollbar(form)
textarea1 = Text(form, width=20, height=10)
textarea1.config(yscrollcommand=scrollbar1.set)
scrollbar1.config(command=textarea1.yview)
textarea1.grid(row=0, column=1, padx=pad_x, pady=pad_y, sticky=W)
scrollbar1.grid(row=0, column=2, padx=pad_x, pady=pad_y, sticky=W)
textbox1.grid(row=1, column=1, padx=pad_x, pady=pad_y, sticky=W)
button1.grid(row=1, column=2, padx=pad_x, pady=pad_y, sticky=W)
form.mainloop()
root = Tk()
Application(root)

So you're using a tkinter.Text box, which supports the .insert method. Let's use it!
def __init__(self,form):
# Lots of your code is duplicated here, so I'm just highlighting the main parts
button1 = Button(form, text='Button1', command = self.addchat)
self.textbox = textbox1 # to make it accessible outside your __init__
self.textarea = textarea1 # see above
form.bind("<Return>", lambda x: self.addchat())
# this is the magic that makes your enter key do something
def addchat(self):
txt = self.textbox.get()
# gets everything in your textbox
self.textarea.insert(END,"\n"+txt)
# tosses txt into textarea on a new line after the end
self.textbox.delete(0,END) # deletes your textbox text