Python Tkinter entry not loading content correct

Question

i am facing a problem. I'm runnig this code.

import tkinter as tk

root = tk.Tk()
def check():
   if len(e.get().split("a")) > 1:
      print("contains a")

e = tk.Entry(frame1)
e.grid(row=4,column=1,columnspan=2,padx = (10,10), pady=(5,10), sticky="w e")
e.bind("<Key>",check)

when i type "a" to the entry I wont get nothing printed. I'll get the result by tiping a second character. I think that it happens because the function gets executed before the content has actualy changed. I tried to add a timer on the beginning of the function but it does nothing. I want get the result by entering the first "a". What should I do?

That seems like a strange way to check if a character is in a string. Why not do `if "a" in e.get():`? — Kevin, Mar 24 '17 at 18:52
Whats your overall goal here? I'll bet if you give us a more specific goal we can tell you a better way to do it. — Novel, Mar 24 '17 at 18:57
What is your ultimate goal? Are you doing input validation, or some sort of data processing? There are special options for input validation. — Bryan Oakley, Mar 24 '17 at 19:05
I tried to live check if the Entry contains an "a". What special options are you tallking @BryanOakley ? — PatoKrivulcik, Mar 25 '17 at 20:10
@PatoKrivulcik: this is what I'm talking about: http://stackoverflow.com/a/4140988/7432 — Bryan Oakley, Mar 25 '17 at 21:58

score 1 · Accepted Answer · answered Mar 24 '17 at 18:58

I think that it happens because the function gets executed before the content has actualy changed.

You're right. If you want the callback to be able to see the character you just typed, you should create a StringVar and bind to that instead of binding to a "<Key>" event on the widget.

import tkinter as tk

frame1 = tk.Tk()
def check(*args):
    if "a" in s.get():
        print("contains a")

s = tk.StringVar()
e = tk.Entry(frame1, textvariable=s)
s.trace("w", check)
e.grid(row=4,column=1,columnspan=2,padx = (10,10), pady=(5,10), sticky="w e")
frame1.mainloop()

Works fine. I didn't know about the StringVar(). One more question, how can I remove the drawing animation of the turtle module. turtle.spped(0) and turtle.speed("fastest") is not working fine for me. I want my picture get drawn instantly. Thanks — PatoKrivulcik, Mar 25 '17 at 16:16

Python Tkinter entry not loading content correct

1 Answers1