Display labels using loop on button press

Question

So I'm reading contents from the database and I have appended necessary elements into lists. I am trying to display each elements in the list in a label. For example, I have a list from the database:

test = ['Name' , 'Age', 'Location']

I want to display the label with text- Name (i.e test[0]) on button press. Likewise, when I press the button again I want the label to display, Age (i.e. test[1]) and so on upto the length of the list. What I tried:

from tkinter import *
import sqlite3

# connecting to the database
conn = sqlite3.connect('database.db')
c = conn.cursor()

# empty lists to later append elements into
all_ids =  []
all_names = []
all_time = []

# execute sql
sql = ('SELECT * FROM appointments')
res = c.execute(sql)
for r in res:
    idd = r[0]
    name = r[1]
    time = r[6]
    all_ids.append(idd)
    all_names.append(name)
    all_time.append(time)
# variable that determines the index of elements on button press (updates)
x = 0
class Application:
    def __init__(self, master):
        self.master = master

        self.heading = Label(master, text="Appointments", font=('arial 60 bold'), fg='steelblue')
        self.heading.place(x=300, y=0)

        self.btn = Button(master, text="Next Patient", width=20, height=2, command=self.func)
        self.btn.place(x=500, y=600)

        self.display = Label(self.master, text="", font=('arial 200 bold'))
        self.display.place(x=500, y=80)

        self.nd = Label(self.master, text="", font=('arial 80 bold'))
        self.nd.place(x=200, y=400)

    def func(self):
        global x
        for i in all_ids:
            self.display.config(text=str(all_ids[x]))
            self.nd.config(text=str(all_names[x]))
            x += 1


root = Tk()
v = Application(root)
root.geometry("1366x768+0+0")
root.resizable(False, False)
root.mainloop()

When I press the button, last element is displayed and when I press again, I get list index out of range. Can anyone please tell me what I'm doing wrong? Thanks

Output is the label of last element in the list and error on clicking again:

Exception in Tkinter callback
Traceback (most recent call last):
  File "/usr/lib/python3.5/tkinter/__init__.py", line 1553, in __call__
    return self.func(*args)
  File "test.py", line 45, in func
    self.display.config(text=str(all_ids[x]))
IndexError: list index out of range

Instead of initialising `x` outside can you try it inside the `fun ()`, like `x=0` and remove that `global x` — Vikas Periyadath, Jan 29 '18 at 05:59
I tried it, it only returns the last element. What I need is to update the label every time the button is clicked — Bibek Bhandari, Jan 29 '18 at 06:05
In that current code I think you are not using that `i` no where. So you can change that loop to `for i in range(len(all_ids)): all_ids[i]` instead of that `x` that those places you can use `i` — Vikas Periyadath, Jan 29 '18 at 06:08
Possible duplicate of [Index Error: list index out of range (Python)](https://stackoverflow.com/questions/16005707/index-error-list-index-out-of-range-python) — Nae, Jan 29 '18 at 14:53

score 1 · Accepted Answer · answered Jan 29 '18 at 09:00

for loop in func seems unnecessary since you are saying you want to show one of your labels on each press. Remove it.

Also you can move x inside of your class if you are only using it in there.

def __init__(self, master):
    ...
    self.x = 0

def func(self):
    self.display.config(text=str(all_ids[self.x]))
    self.nd.config(text=str(all_names[self.x]))
    self.x += 1

Display labels using loop on button press

1 Answers1