I want to populate a ttk.combobox with results from database query - sqlite

Question

i am having a little problem i would need help with.This concerns python ttk.combobox widget
I am new to python just started coding a week ago.
I have a database which is populated by user input.This database is to store a user's stock input(e.g. items, cost, supplier ,etc).This part i have been able to do.
From the database, am using a 'for' loop to get each seperate item from my database query into a ttk.combobox so a user can make selections.
However my problem is,i get an error everytime.
I want the combobox to show all items within my item column from my database query.
From online sources ,i found out an example for ttk.combobox:
list = ['shoe', 'toy', 'bag']
combobox = ttk.Combobox(root)
combobox['values'] = list
This works fine,if i am to use a self-made list
However , i can't find an example for a ttk.combobox using query from sqlite3 in python
Thank you in advance for helping me out with this problem.
An example of how to do it and an explanation of what i did wrong will help me alot.
Forgive me for my poorly organised coding style,i hope to get better at it as time goes on.
from tkinter import *
from tkinter import ttk
import sqlite3
class Example:
def __init__(self,master):
self.master = master
self.win_label = Label(master, text="New Stock Entry")
self.win_label.grid(row=0, columnspan=2,)
self.item_label = Label(master, text="Item Name", fg='black')
self.item_label.grid(row=1, column=0, sticky=W, padx=5, pady=5)
self.unitprice_lab = Label(master, text="Unit Price", fg='black')
self.unitprice_lab.grid(row=2, column=0, sticky=W, padx=5, pady=5)
self.total_price = Label(master, text="Total Price", fg='black')
self.total_price.grid(row=3, column=0, sticky=W, padx=5, pady=5)
self.quantity_lab = Label(master, text="Quantity", fg='black')
self.quantity_lab.grid(row=4, column=0, sticky=W, padx=5, pady=5)
self.manufacturer_lab = Label(master,text="Manufacturer", fg='black')
self.manufacturer_lab.grid(row=5, column=0, sticky=W, padx=5, pady=5)
############### Variables to store input ################
self.item = StringVar()
self.unitp = IntVar()
self.unitn = IntVar()
self.quantity = IntVar()
self.man = StringVar()
############ Widgets############
self.item_entry = Entry(master, width=25,textvariable=self.item)
self.item_entry.grid(row=1, column=1, padx=5, pady=5)
self.unitprice_entry = Entry(master, width=25,textvariable=self.unitp)
self.unitprice_entry.grid(row=2, column=1, sticky=W, padx=5, pady=5)
self.total_price_entry = Entry(master,width=25,textvariable=self.unitn)
self.total_price_entry.grid(row=3, column=1, sticky=W, padx=5, pady=5)
self.quantity_entry = Entry(master,width=25,textvariable=self.quantity)
self.quantity_entry.grid(row=4, column=1, sticky=W, padx=5, pady=5)
self.manufacturer_entry = Entry(master, width=25,textvariable=self.man)
self.manufacturer_entry.grid(row=5, column=1, sticky=W, padx=5, pady=5)
# button for save
self.button_save = Button(master,text="Save",command= self.insert_Dbs)
self.button_save.grid(row=6, column=1, pady=15, padx=10, sticky=W)
def second_window(self): # Second Window to allow user selection
t = Toplevel()
t.geometry('350x290')
t.title('Student Input')
############# widgets ###############
self.label1 = ttk.Label(t, text = 'Student Name')
self.label1.grid(row =0 , column =0)
self.label2 = ttk.Label(t, text='Item Collected')
self.label2.grid(row=0, column=1)
self.label3 = ttk.Label(t, text='Quantity')
self.label3.grid(row=0, column=2)
self.entry1 =ttk.Entry(t, width = 20)
self.entry1.grid(row =1 , column =0)
self.entry2 = ttk.Entry(t, width=20)
self.entry2.grid(row=1, column=2)
self.comb = ttk.Combobox(t,width = 15).grid(row =1 , column =1)
self.comb['value'] = self.combo_input
def insert_Dbs(self): # Function to insert input into database
self.a1 = self.item.get()
self.a2 = self.unitp.get()
self.a3 = self.unitn.get()
self.a4 = self.quantity.get()
self.a5 = self.man.get()
#db = sqlite3.connect('stockdbExample.db')
'''db.execute('create table stocks (item text '
', item_uprice integer,'
' item_nprice integer,'
' quantity integer,'
' manufacturer text )')'''
db = sqlite3.connect('stockdbExample.db')
db.execute('insert into stocks (item,'
' item_uprice,'
' item_nprice,'
' quantity,'
' manufacturer) values (?, ?, ?, ?,?)',
(self.a1, self.a2, self.a3, self.a4, self.a5))
db.commit()
self.combo_input()
self.second_window()
def combo_input(self):
db = sqlite3.connect('stockdbExample.db')
cursor = db.execute('select item from stocks')
for row in cursor.fetchall():
return row
root = Tk()
c = Example(root)
root.mainloop()

Answer 1

First: you forgot () to execute function
self.comb['value'] = self.combo_input()
Second: inside combo_input you use return row so you return only first row, nothing more.
You have to create Python list with all values and then return it.
It can be something like this:
def combo_input(self):
db = sqlite3.connect('stockdbExample.db')
cursor = db.execute('select item from stocks')
result = []
for row in cursor.fetchall():
result.append(row[0])
return result
EDIT: Full, working example:
import tkinter as tk
import tkinter.ttk as ttk
import sqlite3
class Example:
def __init__(self,master):
self.master = master
self.db = sqlite3.connect('stockdbExample.db')
# use only once
self.create_db()
self.cb = ttk.Combobox(master)
self.cb.pack()
self.cb['values'] = self.combo_input()
def combo_input(self):
cursor = self.db.cursor()
cursor.execute('SELECT item FROM stocks')
data = []
for row in cursor.fetchall():
data.append(row[0])
return data
def create_db(self):
cursor = self.db.cursor()
cursor.execute('CREATE TABLE stocks (item text)')
cursor.execute('INSERT INTO stocks (item) VALUES("Hello")')
cursor.execute('INSERT INTO stocks (item) VALUES("World")')
cursor.execute('INSERT INTO stocks (item) VALUES("Tkinter")')
cursor.close()
self.db.commit()
root = tk.Tk()
Example(root)
root.mainloop()