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Why is my Button's command executed immediately when I create the Button, and not when I click it? [duplicate]
(5 answers)
Closed 2 years ago.
I implemented the following code in python to manipulate an own property (here button.text) of the pressed button.
When executing the code I get the following error: "AttributeError: 'Gui' object has no attribute 'button'". Important for my example is, that the button is part of the class and created in its init. Other working examples with a global defined button I found and got running.
#!/usr/bin/python3
# -*- coding: iso-8859-1 -*-
import tkinter
from tkinter import *
from tkinter import ttk
class Gui:
def __init__(self, master):
self.master = master
self.frame = Frame(self.master)
self.frame.pack(fill='both', side='top', expand='True')
self.button = Button(master=self.frame,
text='connect',
height=20,
width=80,
padx=1,
pady=1,
command=self.connect_disconnct(),
compound=LEFT)
self.button.grid(row=0, column=0, padx=5, pady=5, sticky='ew')
mainloop()
def connect_disconnct(self):
if self.button.test == connect:
print("Button pressed -> connect")
self.button.text = "disconnect"
else:
print("Button pressed -> disconnect")
self.button.text = "connect"
if __name__ == '__main__':
form = Tk()
Gui(form)
form.mainloop()
How the own button element can be passed to the callback function so for example the text of the calling object can be changed in the callback function?
Remove the () in this line.
command=self.connect_disconnct(),
You want to hand the button a function to call. The () calls the function, executing it before the attribute self.button is set. Even if there were no reference to self.button in the method you would be handing Button the return value of the method, which in this case is None.
There are some additional things wrong with this code. To get the button text, you need to do this self.button['text'] == 'connect'.
Additionally, you cannot set the text in this way. You need to use the configure() method.
self.button.configure(text="disconnect")
Also, you have one too many calls to mainloop().
Full code:
import tkinter
from tkinter import *
from tkinter import ttk
class Gui:
def __init__(self, master):
self.master = master
self.frame = Frame(self.master)
self.frame.pack(fill='both', side='top', expand='True')
self.button = Button(master=self.frame,
text='connect',
height=20,
width=80,
padx=1,
pady=1,
command=self.connect_disconnct,
compound=LEFT)
self.button.grid(row=0, column=0, padx=5, pady=5, sticky='ew')
def connect_disconnct(self):
if self.button['text'] =='connect':
print("Button pressed -> connect")
self.button.configure(text="disconnect")
else:
print("Button pressed -> disconnect")
self.button.configure(text="connect")
if __name__ == '__main__':
form = Tk()
Gui(form)
form.mainloop()
In addition to #Axe319 answer there is a few things:
You are using the wrong syntax to change the button text, the correct syntax is:
self.button.config(text = "disconnect")
As for getting text from the button:
self.button['text'] == 'connect':
Finally there is a spelling error:
self.button.test == connect:
# x
Related
I am trying to get the following code to work where event calls a function to clear an entry box. Can someone tell me what I am doing wrong. I am not too familiar with Tkinter.
import tkinter as tk
from tkinter import *
class Example(Frame):
def __init__(self):
super().__init__()
self.initUI()
def initUI(self):
self.master.title("Create Trusted Facts")
self.pack(fill=BOTH, expand=True)
frame2 = Frame(self)
frame2.pack(fill=X)
reqSumLbl = Label(frame2, text="Request Summary", width=22)
reqSumLbl.pack(side='left', padx=5, pady=5)
reqSumBox = Entry(frame2, width=100, bg="White", fg="lightgrey", borderwidth=1)
reqSumBox.insert(0, "Enter the Request Summary here")
reqSumBox.pack(fill=X, padx=50, pady=5, expand=True)
reqSumBox.bind("<Button-1>", self.clear_reqSumBox)
def clear_reqSumBox(self, reqSumBox):
reqSumBox.delete(0, END)
reqSumBox.config(fg="black")
global SummaryText
SummaryText = reqSumBox.get()
def main():
root = Tk()
root.geometry("500x550+350+50")
app = Example()
root.mainloop()
if __name__ == '__main__':
main()
reqSumBox.bind("<Button-1>", self.clear_reqSumBox)
When binding any event to a function, it automatically needs to take in a parameter called event, there are 2 ways to fix your code.
1.
reqSumBox.bind("<Button-1>", lambda event: self.clear_reqSumBox)
Make lambda function which takes in event and calls function.
2.
def reqSumBox(self, reqSumBox, event=None)
Add optional event parameter in reqSumBox function.
I personally use the first one.
First of all, why do you have two imports at the start of your Python script at they're both the same library, choose one it's incorrect.
About your question, it fails because you didn't provide the clicked object, it provided you as the first argument of the bind function the Event that happened.
I recommend you make your object a part of your current working class (Class Example), like that:
import tkinter as tk
from tkinter import *
class Example(Frame):
def __init__(self):
super().__init__()
self.initUI()
def initUI(self):
self.master.title("Create Trusted Facts")
self.pack(fill=BOTH, expand=True)
frame2 = Frame(self)
frame2.pack(fill=X)
reqSumLbl = Label(frame2, text="Request Summary", width=22)
reqSumLbl.pack(side='left', padx=5, pady=5)
# Check my changes here.
self.reqSumBox = Entry(frame2, width=100, bg="White", fg="lightgrey", borderwidth=1)
self.reqSumBox.insert(0, "Enter the Request Summary here")
self.reqSumBox.pack(fill=X, padx=50, pady=5, expand=True)
self.reqSumBox.bind("<Button-1>", self.clear_reqSumBox)
# Changed the argument name to "event".
def clear_reqSumBox(self, event):
self.reqSumBox.delete(0, END)
self.reqSumBox.config(fg="black")
def main():
root = Tk()
root.geometry("500x550+350+50")
app = Example()
root.mainloop()
if __name__ == '__main__':
main()
Check where I comment and analyze this code.
The callback of bind() requires an argument which is the event object. So modify the callback function definition as below:
def clear_reqSumBox(self, event):
# get the widget triggering this event
reqSumBox = event.widget
reqSumBox.delete(0, END)
reqSumBox.config(fg="black")
# after that reqSumBox.get() will return empty string
global SummaryText
# SummaryText = "" will have same result of below line
SummaryText = reqSumBox.get()
However the entry will be cleared whenever you click on the entry. Is it really what you want?
i wrote bellow code in python 3.6.2 by tkinter,I want the cursor move to password textbox when user press Enter key in username textbox.
from tkinter import *
class Application(Frame):
def __init__(self,master):
super(Application, self).__init__(master)
self.grid()
self.create_main()
def create_main(self):
print("testing")
self.title = Label(self, text=" Stuck In The Circle ")
self.title.grid(row=0, column=2)
self.user_entry_label = Label(self, text="Username: ")
self.user_entry_label.grid(row=1, column=1)
self.user_entry = Entry(self)
self.user_entry.grid(row=1, column=2)
self.pass_entry_label = Label(self, text="Password: ")
self.pass_entry_label.grid(row=2, column=1)
self.pass_entry = Entry(self)
self.pass_entry.grid(row=2, column=2)
self.user_entry = Entry(self, justify="right")
self.pass_entry = Entry(self, justify="right")
self.sign_in_butt = Button(self, text="Sign In",command = self.logging_in)#SIGN IN BUTTON
self.sign_in_butt.grid(row=5, column=2)
def logging_in(self):
user_get = self.user_entry.get()
pass_get = self.pass_entry.get()
root = Tk()
root.title("Stuck in the Circle")
root.geometry("400x100")
app = Application(root)
root.mainloop()
How can do it?
This is actually a lot simpler than I expected it to be.
We can use .bind() to get a callback on the <Return> event. This means that every time the return character is pressed whenever the defined widget is in focus we get a callback.
In order to get it to cycle to the next widget we can use this answer from Bryan Oakley:
def focus_next_window(event):
event.widget.tk_focusNext().focus()
return("break")
text_widget=Text(...) text_widget.bind("<Tab>", focus_next_window)
Important points about this code:
The method tk_focusNext() returns the next widget in the keyboard
traversal hierarchy. the method focus() sets the focus to that widget
returning "break" is critical in that it prevents the class binding
from firing. It is this class binding that inserts the tab character,
which you don't want.
So, applying the same logic in our situation we can use something like the below:
from tkinter import *
class App:
def __init__(self, root):
self.root = root
self.entry1 = Entry(self.root)
self.entry2 = Entry(self.root)
self.entry1.pack()
self.entry2.pack()
self.entry1.bind("<Return>", self.callback)
def callback(self, event):
event.widget.tk_focusNext().focus()
root = Tk()
App(root)
root.mainloop()
The following script creates a tkinter window with a text label, exit button and change-text button:
from tkinter import *
from tkinter import ttk
class Window(Frame):
def __init__(self, master=None):
Frame.__init__(self, master)
self.master = master
self.init_window()
def init_window(self):
test_label = Label(root, text="none").grid(row=0, column=0, sticky=W)
change_text_btn = Button(root, text="change_text", command=self.set_label_text).grid(row=2, column=0, sticky=W)
exit_btn = Button(root, text="Exit", command=self.client_exit).grid(row=2, column=1, sticky=W)
def set_label_text(self):
test_label.config(text='changed the value')
def client_exit(self):
exit()
if __name__ == '__main__':
root = Tk()
app = Window(root)
root.mainloop()
After click on change_text_btn I get a NameError: name 'test_label' is not defined error. So the problem is that test_label created in init_window() is not avaliable from set_label_text() beacuse of the scope. How do I fix it?
To overcome the issue, you can make test_label an instance variable by prefixing it with self. Besides that, when you chain methods like that, what happens is you assign None to your variable, since grid() returns None - instead, place each method in a separate line (this stands for all of your buttons):
self.test_label = Label(root, text="none")
self.test_label.grid(row=0, column=0, sticky=W)
Of course, you'd need to refer to it with self.test_label later on in your set_label_text function.
Other than that, I suggest you get rid of from tkinter import *, since you don't know what names that imports. It can replace names you imported earlier, and it makes it very difficult to see where names in your program are supposed to come from. Use import tkinter as tk instead.
This is my Copy&Paste program:
from tkinter import *
import Pmw
class CopyTextWindow(Frame):
def __init__(self):
Frame.__init__(self)
Pmw.initialise()
self.pack(expand=YES, fill=BOTH)
self.master.title("ScrolledText Demo")
self.frame1=Frame(self, bg="White")
self.frame1.pack(expand=YES, fill=BOTH)
self.text1=Pmw.ScrolledText(self, text_width=25, text_height=12, text_wrap=WORD,
hscrollmode="static", vscrollmode="static")
self.text1.pack(side=LEFT, expand=YES, fill=BOTH, padx=5, pady=5)
options = ["Copy", "Paste"]
self.selectedOption = StringVar()
self.menu = Menu(self.frame1, tearoff=0)
for option in options:
self.menu.add_radiobutton( label=option, variable=self.selectedOption,
command=self.ExecuteOption)
self.text1.bind("<Button-3>", self.popUpMenu)
def popUpMenu(self, event):
self.menu.post(event.x_root, event.y_root)
def ExecuteOption(self):
if self.selectedOption.get()=="Copy":
self.CopiedText=self.text1.get(SEL_FIRST, SEL_LAST)
else:
self.text1.settext( self.text1.get()+self.CopiedText)
def main():
CopyTextWindow().mainloop()
if __name__=="__main__":
main()
In this program, I want to make a GUI, that in it you can copy and paste text that you have selected. when you press the right mouse button, a little menu with the Copy and Paste options.
The program opens up, but when I press the right mouse button, no menu appears. Python also doesn't complain with an error.
I need to understand my mistake in this code.
For a reason I ignore, the event doesn't seem to be triggered when the bind is on the Text or on the Frame, but it works when it's on the main window:
from tkinter import *
import Pmw
class CopyTextWindow(Frame):
def __init__(self, master=None):
# I've added a master option to pass to the frame
Frame.__init__(self, master)
Pmw.initialise()
self.pack(expand=YES, fill=BOTH)
self.master.title("ScrolledText Demo")
self.frame1=Frame(self, bg="White")
self.frame1.pack(expand=YES, fill=BOTH)
self.text1=Pmw.ScrolledText(self, text_width=25, text_height=12, text_wrap=WORD,
hscrollmode="static", vscrollmode="static")
self.text1.pack(side=LEFT, expand=YES, fill=BOTH, padx=5, pady=5)
options = ["Copy", "Paste"]
self.selectedOption = StringVar()
self.menu = Menu(self.frame1, tearoff=0)
for option in options:
self.menu.add_radiobutton( label=option, variable=self.selectedOption,
command=self.ExecuteOption)
def popUpMenu(self, event):
print("ok")
self.menu.post(event.x_root, event.y_root)
def ExecuteOption(self):
if self.selectedOption.get()=="Copy":
self.CopiedText=self.text1.get(SEL_FIRST, SEL_LAST)
else:
self.text1.settext( self.text1.get()+self.CopiedText)
def main():
# main window
root = Tk()
ctw = CopyTextWindow(root)
# bind on the main window
root.bind("<Button-3>", ctw.popUpMenu)
root.mainloop()
if __name__=="__main__":
main()
I'm working on my very first Python GUI and I'm trying to modify this tkinter example, but I simply cannot figure out how to write a callback function for the OK button that will pass on the entered value to the main program.
#!/usr/bin/python
# -*- coding: utf-8 -*-
from Tkinter import Tk, BOTH, StringVar, IntVar
from ttk import Frame, Button, Style, Label, Entry
class Example(Frame):
def __init__(self, parent):
Frame.__init__(self, parent)
self.parent = parent
self.initUI()
def initUI(self):
self.parent.title("Get Value")
self.style = Style()
self.style.theme_use("default")
self.pack(fill=BOTH, expand=1)
valueLabel = Label(self, text="Value: ")
valueLabel.place(x=10, y=10)
value=StringVar(None)
value.set("this is the default value")
valueEntry=Entry(self, textvariable=value)
valueEntry.place(x=70, y=10)
quitButton = Button(self, text="Quit", command=self.quit)
quitButton.place(x=10, y=50)
okButton = Button(self, text="OK", command=self.quit)
okButton.place(x=120, y=50)
def main():
root = Tk()
root.geometry("220x100+300+300")
app = Example(root)
root.mainloop()
if __name__ == '__main__':
main()
I've read a gazillion of tutorials, but none of them explains this clearly. Theoretically, I should be able to get the selected value with value.get(), but I keep getting error messages no matter where I put it. Also, AFAIK, I should be able to define a default value with value.set(), but this doesn't seem to have an effect, since the text box is empty when I run the program.
What is the easiest way to pass on values to the main python program after root.mainloop() terminates? (The actual dialog box contains several entry boxes for entering string and integer values.)
I.e. I want to be able to use something like:
root = Tk()
root.geometry("220x100+300+300")
app = Example(root)
root.mainloop()
print value
print value2
print value3
How do I define default values for entry boxes?
Change every occurrence of the value variable with self.value. This should fix it and the default value will be displayed.
UPDATE
from Tkinter import Tk, BOTH, StringVar, IntVar
from ttk import Frame, Button, Style, Label, Entry
class Example(Frame):
def __init__(self, parent):
Frame.__init__(self, parent)
self.parent = parent
self.initUI()
def showMe(self):
print(self.value.get())
def initUI(self):
self.parent.title("Get Value")
self.style = Style()
self.style.theme_use("default")
self.pack(fill=BOTH, expand=1)
valueLabel = Label(self, text="Value: ")
valueLabel.place(x=10, y=10)
self.value=StringVar(None)
self.value.set("this is the default value")
valueEntry=Entry(self, textvariable=self.value)
valueEntry.place(x=70, y=10)
quitButton = Button(self, text="Quit", command=self.quit)
quitButton.place(x=10, y=50)
okButton = Button(self, text="OK", command=self.showMe)
okButton.place(x=120, y=50)
def main():
root = Tk()
root.geometry("220x100+300+300")
app = Example(root)
root.mainloop()
if __name__ == '__main__':
main()
Both your quitButton and okButton call the self.quit functions. So no mater what value you enter when you press the OK button you are calling the quit function which has its own problems as well outside the scope of your question.
Try to define value as self.value and make the okButton call a function that does: print self.value.get().