pyqt/further/mvc_2.py

import random
import sys

from PyQt5.QtCore import Qt
from PyQt5.QtWidgets import QMainWindow, QFormLayout, QLineEdit, QSpinBox, QComboBox, QPushButton, QApplication, \
    QWidget, QCheckBox

model = {
    "name": "Johnina Smith",
    "age": 10,
    "favorite_icecream": "Vanilla",
    "disable_details": False,
}

backups = []


class MainWindow(QMainWindow):

    def __init__(self):
        super().__init__()
        self.setWindowTitle("MVC Example")

        layout = QFormLayout()

        # Dictionary to store the form data, with default data.
        self.name = QLineEdit()
        self.name.textChanged.connect(self.on_name_changed)
        self.age = QSpinBox()
        self.age.setRange(0, 200)
        self.age.valueChanged.connect(self.on_age_changed)
        self.icecream = QComboBox()
        self.icecream.addItems(["Vanilla", "Strawberry", "Chocolate"])
        self.icecream.currentTextChanged.connect(self.on_icecream_changed)
        self.save_btn = QPushButton("Save")
        self.save_btn.clicked.connect(self.on_save_clicked)
        self.restore_btn = QPushButton("Restore")
        self.restore_btn.clicked.connect(self.on_restore_clicked)
        self.disable_details = QCheckBox("Disable Details?")
        self.disable_details.toggled.connect(self.on_disable_details_toggled)

        layout.addRow("Name", self.name)
        layout.addRow("Age", self.age)
        layout.addRow("Favorite Ice Cream", self.icecream)
        layout.addWidget(self.disable_details)  # QCheckBox has its own label.
        layout.addRow(self.save_btn)
        layout.addRow(self.restore_btn)
        layout.setLabelAlignment(Qt.AlignLeft)

        widget = QWidget()
        widget.setLayout(layout)
        self.setCentralWidget(widget)

        self.update_ui()

    def update_ui(self):
        self.name.setText(model["name"])
        self.age.setValue(model["age"])
        self.icecream.setCurrentText(model["favorite_icecream"])
        self.disable_details.setChecked(model["disable_details"])

        self.age.setDisabled(model["disable_details"])
        self.icecream.setDisabled(model["disable_details"])

    def on_name_changed(self, value):
        model["name"] = value
        print(model)

    def on_age_changed(self, value):
        model["age"] = value
        print(model)

    def on_icecream_changed(self, value):
        model["favorite_icecream"] = value
        print(model)

    def on_save_clicked(self):
        backups.append(model.copy())
        print("SAVE:", model)
        print("BACKUPS:", len(backups))

    def on_restore_clicked(self):
        if not backups:
            return
        random.shuffle(backups)
        backup = backups.pop()  # Remove a backup
        model.update(backup)  # Overwrite the data in the model
        self.update_ui()
        print("RESTORE:", model)
        print("BACKUPS:", len(backups))

    def on_disable_details_toggled(self, value):
        model["disable_details"] = value
        print(model)
        self.update_ui()


if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = MainWindow()
    window.show()
    app.exec_()