Python Tkinter Text Widget .get method error

Question

Hi,

I'm very new to Python, sort of following Dive into Python 2 and wanted to dabble with some Tkinter programming. I've tried to make a little program that takes 3 sets of words and makes combinations of each word in the 3 sets to make keywords for websites. When I run the script, the GUI appears as expected, but I get the following error when I click on the Create Combinations button

Exception in Tkinter callback
Traceback (most recent call last):
  File "/usr/lib/python2.6/lib-tk/Tkinter.py", line 1413, in __call__
    return self.func(*args)
  File "combomaker.py", line 34, in makeCombinations
    primaryraw = primaryKeyWordsBox.get()
AttributeError: 'NoneType' object has no attribute 'get'

The code I'm trying to fix

#!/usr/bin/env python
from Tkinter import *

primaryKeyWordsLabel = None
primaryKeyWordsBox = None
secondaryKeyWordsLabel = None
secondaryKeyWordsBox = None
tertiaryKeyWordsLabel = None
tertiaryKeyWordsBox = None

class Application(Frame):
 def __init__(self, master=None, padx = 10, pady= 10):
  Frame.__init__(self, master)
  self.grid()
  self.createWidgets()

 def createWidgets(self):
  self.primaryKeyWordsLabel = LabelFrame(text="Primary Key Words", padx=10, pady=10)
  self.primaryKeyWordsLabel.grid()
  self.primaryKeyWordsBox = Text(primaryKeyWordsLabel, autoseparators=True, height=5, undo=True)
  self.primaryKeyWordsBox.grid()
  self.secondaryKeyWordsLabel = LabelFrame(text="Secondary Key Words", padx=10, pady=10)
  self.secondaryKeyWordsLabel.grid()
  self.secondaryKeyWordsBox = Text(secondaryKeyWordsLabel, autoseparators=True, height=5, undo=True)
  self.secondaryKeyWordsBox.grid()
  self.tertiaryKeyWordsLabel = LabelFrame(text="Tertiary Key Words", padx=10, pady=10)
  self.tertiaryKeyWordsLabel.grid()
  self.tertiaryKeyWordsBox = Text(tertiaryKeyWordsLabel, autoseparators=True, height=5, undo=True)
  self.tertiaryKeyWordsBox.grid()
  self.goButton = Button(text="Create Combinations", command=makeCombinations)
  self.goButton.grid()

def makeCombinations():
  primaryraw = primaryKeyWordsBox.get()
  primary = primaryraw.split(', ')
  secondaryraw = secondaryKeyWordsBox.get()
  secondary = secondaryraw.split(', ')
  tertiaryraw = tertiaryKeyWordsBox.get()
  tertiary = tertiaryraw.split(', ')
  output=[]
  filename = "output.txt" 
  for i in range(len(primary)):
   for j in range(len(secondary)):
    for k in range(len(tertiary)):
     rawcombo=str(primary[i])+" "+str(secondary[j])+" "+str(tertiary[k])
     output.append(rawcombo)
  FILE = open(filename, w)
  for combo in output:
   FILE.write(combo+",\n")
  FILE.close()
app = Application()                    
app.master.title("Keyword Generator") 
app.mainloop()    

I may have thrown myself into GUI programming too fast, this is my first attempt at any GUI work but not my first time programming.
Many thanks in advance :)

Answer 1

You're trying to access

primaryKeyWordsBox

outside the class Application in the (free) function makeCombinations(..).

You could make makeCombinations(..) a member of Application by indenting it like the other member functions and add the self argument:

 def makeCombinations(self):

You should modify the binding of the makeCombinations(..) to the button:

...,command = self.makeCombinations)

Then you'll have to add self. when you're trying to access the members of this class:

 primaryraw = self.primaryKeyWordsBox.get(1.0,END)
 ...
 secondaryraw = self.secondaryKeyWordsBox.get(1.0,END)
 ...
 tertiaryraw = self.tertiaryKeyWordsBox.get(1.0,END)

(I found the examples how to use get here).

If you want to open a file for writing, you should do:

 FILE = open(filename, "w")

instead of

 FILE = open(filename, w)