将值从 TopLevel 对象返回到根对象的 Tkinter 方法

Question

I created a Tkinter app that calls TopLevel objects from another file (for menu bar options).

In my main.py , I have this code:

...
def create():
    funct.createNew()
...

menubar = tk.Menu(window)
#file menu
file = tk.Menu(menubar, tearoff=0)
file.add_command(label='Create new', command=create)
...

And the function being called from functions.py file (I removed the window attributes for simplicity):

def linkToDB():
    global create

    #call the function to create virtual file
    file = sql.generateDB()
    #destroy the createNew window
    create.destroy()

    #debugging purposes
    print("Virtual file:", file)

def createNew():
    #make this global to destroy this window later
    global create

    create = tk.Toplevel()
    ...
    #option 1
    container1 = tk.Frame(create)
    ...
    #generate virtual SQLite file
    btn1 = tk.Button(container1, text="Create", command= lambda: linkToDB())

The above code displays a TopLevel window that will be called by Create button in main.py , which in turn calls a function from sql.py (by that button within TopLevel window) to create temporary SQlite file:

import sqlite3 as sq

#create a virtual sqlite file
def generateDB():
    temp = sq.connect(':memory:')
    temp.execute...
    return temp

My problem is how to return the value of temp from generateDB() to main.py (specifically after destroying the TopLevel window)? I am confused on how to pass this value across the .py files. And whether my approach is viable or not (also looking for suggestions).

PS I intentionally destroyed the TopLevel window in linkToDB() since it is guaranteed that my temporary SQlite file will be generated.

Answer 1

You can modify funct.createNew() to return the virtual file to main.py . However you need to make the toplevel window a modal window in order to return the virtual file after the toplevel window is destroyed.

Below is the modified functions.py :

import tkinter as tk
import sql

# pass the toplevel window as an argument instead of using global variable
def linkToDB(create):
    # use an attribute of the toplevel window to store the "virtual db file"
    create.file = sql.generateDB()
    create.destroy()
    print('Virtual file:', create.file)

def createNew():
    create = tk.Toplevel()
    ...
    container1 = tk.Frame(create)
    ...
    btn1 = tk.Button(container1, text='Create', command=lambda: linkToDB(create))
    ...
    # wait for window destroy (works like a modal dialog)
    create.wait_window(create)
    # return the "virtual db file"
    return create.file

Then you can get the virtual db file in main.py :

def create():
    # if you want the "virtual db file" be accessed by other function
    # declare it as global variable
    #global db_file
    db_file = funct.createNew()
    print(db_file)
    ...

...