How to get rid of curly braces from expanded list

Question

I'm new to Python, so please bear with me. I'm trying to populate an optionmenu with rows from an SQLite database. The problem is that when a cell contains a space, the option appears with {} around it. What is the proper way to do this?

from tkinter import *
import sqlite3

conn = sqlite3.connect('db_name.db')
c = conn.cursor()
c.execute('''SELECT client_name FROM clients
         ORDER BY client_name''')
clients = c.fetchall()

master = Tk()
variable = StringVar(master)
variable.set("Select Client")
client = OptionMenu(master, variable, *tuple(clients))

Answer 1

The method accepts strings for options, each separated as a positional argument (see this example from effbot).

You are actually sending tuples and not strings; because fetchall() will return a tuple for each row, and the elements in the tuple represent columns from the result set.

As you are only selecting one column in your query, your results contain a one-tuple (a tuple with only one element):

(('Client1',), ('Client2',), ('Client 3',))
#----------^ this is a single element tuple

You need to send to the method:

client_list = OptionMenu(master, client, 'Client1', 'Client2', 'Client3')

You are actually sending:

client_list = OptionMenu(master, client, ('Client1',), ('Client2',), ('Client3',))

The reason your fix works is because it collapses the tuple, so instead of a tuple of tuples, its a tuple of strings:

>>> clients = (('Client1',), ('Client2',), ('Client 3',))
>>> sum(clients, ())
('Client1', 'Client2', 'Client 3')

There is nothing wrong with your fix, and you can implement it another way as well:

clients = [i[0] for i in c.fetchall()] # Now you have gotten rid of the
                                       # inner tuple

Answer 2

You can use regular expression to get the similar result.

import re
clients = [re.sub('[{}]', '',x) for x in c.fetchall()]

Answer 3

I don't understand why, but this works:

client_tuple = sum(clients, ())
client_list = OptionMenu(master, client, *client_tuple)