Auto-Save Form Data in Tkinter – Remember User Input in Python GUI

 

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💾 Bonus Part 6: Auto-Save Forms and User State in Tkinter – No Data Left Behind

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📘 Overview

In this part, you’ll learn how to make your app remember user input between sessions by implementing:

• Auto-save feature for form data

• Restore form state when the app restarts

• Use of JSON files to persist data

• Good for apps like note-taking, to-do lists, or config dashboards

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✅ Why Auto-Save?

• Prevents data loss if the user closes the app accidentally

• Makes your app feel more modern and user-friendly

• Especially helpful for longer forms or repeat users

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📦 What You’ll Use

• json – to store data

• Tkinter's .get() and .insert() to read/write field values

• File I/O (open()) for saving/loading

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✅ Example: Save and Load Form Data

import tkinter as tk
import json
import os

SAVE_FILE = "form_data.json"

class AutoSaveApp(tk.Tk):
    def __init__(self):
        super().__init__()
        self.title("Auto-Save Form")
        self.geometry("300x200")

        tk.Label(self, text="Name:").pack()
        self.name_entry = tk.Entry(self)
        self.name_entry.pack()

        tk.Label(self, text="Email:").pack()
        self.email_entry = tk.Entry(self)
        self.email_entry.pack()

        self.protocol("WM_DELETE_WINDOW", self.on_close)

        self.load_data()

    def load_data(self):
        if os.path.exists(SAVE_FILE):
            with open(SAVE_FILE, "r") as f:
                data = json.load(f)
                self.name_entry.insert(0, data.get("name", ""))
                self.email_entry.insert(0, data.get("email", ""))

    def on_close(self):
        data = {
            "name": self.name_entry.get(),
            "email": self.email_entry.get()
        }
        with open(SAVE_FILE, "w") as f:
            json.dump(data, f)
        self.destroy()

if __name__ == "__main__":
    app = AutoSaveApp()
    app.mainloop()

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✅ How It Works

• When the app closes, it writes the form data to form_data.json

• When the app starts, it checks for the file and restores the values

• All done with standard JSON and basic file handling

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🔐 Bonus: Encrypt the File (Optional)

For basic privacy:

import base64

# To save
encoded = base64.b64encode(json.dumps(data).encode()).decode()
with open(SAVE_FILE, "w") as f:
    f.write(encoded)

# To load
with open(SAVE_FILE, "r") as f:
    encoded = f.read()
    data = json.loads(base64.b64decode(encoded.encode()).decode())

Note: This is not real encryption—use cryptography or similar for secure apps.

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💡 Recap

In this part, you learned how to:

• Automatically save form fields on close

• Restore user input on app restart

• Use JSON for lightweight data persistence

🎉 You’ve now made your GUI more intelligent and user-friendly.

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Would you like to move to Bonus Part 7: Building a Notification System (Popups & Toasts)

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