I don't understand why a messagebox (or simpledialog) breaks the flow of the following code. The code basically validates an entry box in python 3.5. It checks that the field only contain numeric values and that it does't go over 9 digits long, the entry box can be empty though. The addition of a message to the user, after they OK it, allows the entry box to be more than 9 digits and accepts letter which of course I don't want it to do.
from tkinter import *
from tkinter import simpledialog
from tkinter import messagebox
root = Tk()
root.title("Zebra")
root.update_idletasks()
root.geometry("350x200+600+300")
root.config(bg="blue")
def okay(old,new): #,c,d,e,f,g,h):
try:
x = int(new)
except ValueError as ex:
if len(new) == 0:
return True
else:
return False
else:
if len(new) > 9:
messagebox.showerror("Error","Entry is too long")
# When messagebox is removed or commented out all is working ok
# but add below line and BINGO it works again :-)
txtNorm.config(validate='all', vcmd=vcmd)
# New line above as of 08/03/2016 brings validation back.
return False
elif len(new) <=9:
return True
finally:
if len(new) > 9:
return False
pass
def txtNormToggle(event): # When the user double clicks the field to enter or correct a number.
txtNorm.config(state="normal")
def txtNormFinished(a):
txtNorm.config(state="disabled")
root.focus()
vcmd=(root.register(okay),'%s','%P')
txtNorm = Entry(root)
txtNorm.grid(row=1, column=1,padx=(15,15),pady=(15,15), sticky=E+W)
txtNorm.insert(0,"123")
txtNorm.config(state="disabled", justify="center", validate='all', vcmd=vcmd)
txtNorm.bind('<Button>',txtNormToggle)
txtNorm.bind('<Control-z>',txtNormFinished)
txtNorm.bind('<Escape>',txtNormFinished)
txtNorm.bind('<Return>',txtNormFinished)
root.mainloop()
The above without the messagebox stops the user entering anything other than digits, which i want, with messagebox once OK is clicked the entry field allows more than 9 digits and other characters
edit: ok so I have created my own pop-up child window and the validation still goes out the window, suspect it is something to do with loss of focus from the main window killing the validation from the entry box. Any ideas please.
