hi!
i have developed an app with pyside6 (i think it also would work with pyqt6) with a form with many widgets (QLineEdit, QCheckBox, QComboBox).
i want to know how i can save and restore all the values of all widgets.
the only thing i found was self._dict_ but that’s a very long list and i couldn’t find a way to save it.
thanks
Hi @HeinKurz there are various ways to do this. The one I prefer is to use a separate model (which can just be a dictionary) and then sync that with the widgets. You can get clever and sync these things automatically, or just iterate over the widgets in a standard loop & assign the values into the dictionary, or pull them out.
Below is a simple example from my book.
import sys
from PySide6.QtWidgets import (
QApplication,
QComboBox,
QFormLayout,
QLineEdit,
QMainWindow,
QPushButton,
QSpinBox,
QWidget,
)
# Model is a simple dictionary to start.
model = {
"name": "Johnina Smith",
"age": 10,
"favorite_icecream": "Vanilla",
}
class MainWindow(QMainWindow):
def __init__(self):
super().__init__()
self.setWindowTitle("My App")
layout = QFormLayout()
# Dictionary to store the form data, with default data.
self.name = QLineEdit()
self.name.setText(model["name"])
self.name.textChanged.connect(
self.handle_name_changed
)
self.age = QSpinBox()
self.age.setRange(0, 200)
self.age.setValue(model["age"])
self.age.valueChanged.connect(self.handle_age_changed)
self.icecream = QComboBox()
self.icecream.addItems(
["Vanilla", "Strawberry", "Chocolate"]
)
self.icecream.setCurrentText(model["favorite_icecream"])
self.icecream.currentTextChanged.connect(
self.handle_icecream_changed
)
self.save_btn = QPushButton("Save")
self.restore_btn = QPushButton("Restore")
layout.addRow("Name", self.name)
layout.addRow("Age", self.age)
layout.addRow("Favorite Ice cream", self.icecream)
layout.addRow(self.save_btn)
layout.addRow(self.restore_btn)
widget = QWidget()
widget.setLayout(layout)
self.setCentralWidget(widget)
def handle_name_changed(self, name):
model["name"] = name
print(model)
def handle_age_changed(self, age):
model["age"] = age
print(model)
def handle_icecream_changed(self, icecream):
model["favorite_icecream"] = icecream
print(model)
app = QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec()
You can take this further, for example: below we use a dictionary subclass which fires off a signal when any value is changed. You can use this to “listen” to changes on the model, and update other windows.
import random
import sys
from collections import UserDict
from PySide6.QtCore import QObject, Signal
from PySide6.QtWidgets import (
QApplication,
QCheckBox,
QComboBox,
QFormLayout,
QLineEdit,
QMainWindow,
QPushButton,
QSpinBox,
QWidget,
)
class DataModelSignals(QObject):
# Emit an "updated" signal when a property changes.
updated = Signal()
class DataModel(UserDict):
def __init__(self, *args, **kwargs):
self.signals = DataModelSignals()
super().__init__(*args, **kwargs)
def __setitem__(self, key, value):
previous = self.get(key) # Get the existing value.
super().__setitem__(key, value) # Set the value.
if value != previous: # There is a change.
self.signals.updated.emit() # Emit the signal.
print(self) # Show the current state.
model = DataModel(
name="Johnina Smith",
age=10,
favorite_icecream="Vanilla",
disable_details=False,
)
# We store the backups as a simple list.
backups = []
class MainWindow(QMainWindow):
def __init__(self):
super().__init__()
self.setWindowTitle("My App")
layout = QFormLayout()
# Dictionary to store the form data, with default data.
self.name = QLineEdit()
self.name.textChanged.connect(self.handle_name_changed)
self.age = QSpinBox()
self.age.setRange(0, 200)
self.age.valueChanged.connect(self.handle_age_changed)
self.icecream = QComboBox()
self.icecream.addItems(
["Vanilla", "Strawberry", "Chocolate"]
)
self.icecream.currentTextChanged.connect(
self.handle_icecream_changed
)
self.save_btn = QPushButton("Save")
self.save_btn.pressed.connect(self.handle_save_btn)
self.restore_btn = QPushButton("Restore")
self.restore_btn.pressed.connect(self.handle_restore_btn)
self.disable_details = QCheckBox("Disable details?")
self.disable_details.toggled.connect(
self.handle_disable_details
)
layout.addRow("Name", self.name)
layout.addRow("Age", self.age)
layout.addRow("Favorite Ice cream", self.icecream)
layout.addWidget(
self.disable_details
) # QCheckBox has it's own label.
layout.addRow(self.save_btn)
layout.addRow(self.restore_btn)
widget = QWidget()
widget.setLayout(layout)
self.setCentralWidget(widget)
# __init__ ...
self.update_ui()
# Hook our UI sync into the model updated signal.
model.signals.updated.connect(self.update_ui)
def update_ui(self):
"""Synchronise the UI with the current model state."""
self.name.setText(model["name"])
self.age.setValue(model["age"])
self.icecream.setCurrentText(model["favorite_icecream"])
self.disable_details.setChecked(model["disable_details"])
# Enable/disable fields based on the disable_details state.
# disable_details is True/False, setting setDisabled to True
# disables the field.
self.age.setDisabled(model["disable_details"])
self.icecream.setDisabled(model["disable_details"])
def handle_name_changed(self, name):
model["name"] = name
def handle_age_changed(self, age):
model["age"] = age
def handle_icecream_changed(self, icecream):
model["favorite_icecream"] = icecream
def handle_disable_details(self, checked):
model["disable_details"] = checked
def handle_save_btn(self):
# Save a copy of the current model (if we don't copy,
# changes will modify the backup!)
backups.append(model.copy())
print("SAVE:", model)
print("BACKUPS:", len(backups))
def handle_restore_btn(self):
# Randomly get a backup.
if not backups:
return # Ignore if empty.
random.shuffle(backups)
backup = backups.pop() # Remove a backup.
model.update(backup) # Overwrite the data in the model.
print("RESTORE:", model)
print("BACKUPS:", len(backups))
app = QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec()
Below, demonstrating syncing across two windows.
import random
import sys
from collections import UserDict
from PySide6.QtCore import QObject, Signal
from PySide6.QtWidgets import (
QApplication,
QCheckBox,
QComboBox,
QFormLayout,
QLineEdit,
QMainWindow,
QPushButton,
QSpinBox,
QWidget,
)
class DataModelSignals(QObject):
# Emit an "updated" signal when a property changes.
updated = Signal()
class DataModel(UserDict):
def __init__(self, *args, **kwargs):
self.signals = DataModelSignals()
super().__init__(*args, **kwargs)
def __setitem__(self, key, value):
previous = self.get(key) # Get the existing value.
super().__setitem__(key, value) # Set the value.
if value != previous: # There is a change.
self.signals.updated.emit() # Emit the signal.
print(self) # Show the current state.
model = DataModel(
name="Johnina Smith",
age=10,
favorite_icecream="Vanilla",
disable_details=False,
)
# We store the backups as a simple list.
backups = []
class MainWindow(QMainWindow):
def __init__(self):
super().__init__()
self.setWindowTitle("My App")
layout = QFormLayout()
# Dictionary to store the form data, with default data.
self.name = QLineEdit()
self.name.textChanged.connect(self.handle_name_changed)
self.age = QSpinBox()
self.age.setRange(0, 200)
self.age.valueChanged.connect(self.handle_age_changed)
self.icecream = QComboBox()
self.icecream.addItems(
["Vanilla", "Strawberry", "Chocolate"]
)
self.icecream.currentTextChanged.connect(
self.handle_icecream_changed
)
self.save_btn = QPushButton("Save")
self.save_btn.pressed.connect(self.handle_save_btn)
self.restore_btn = QPushButton("Restore")
self.restore_btn.pressed.connect(self.handle_restore_btn)
self.disable_details = QCheckBox("Disable details?")
self.disable_details.toggled.connect(
self.handle_disable_details
)
layout.addRow("Name", self.name)
layout.addRow("Age", self.age)
layout.addRow("Favorite Ice cream", self.icecream)
layout.addWidget(
self.disable_details
) # QCheckBox has it's own label.
layout.addRow(self.save_btn)
layout.addRow(self.restore_btn)
widget = QWidget()
widget.setLayout(layout)
self.setCentralWidget(widget)
self.update_ui()
# Hook our UI sync into the model updated signal.
model.signals.updated.connect(self.update_ui)
def update_ui(self):
"""Synchronise the UI with the current model state."""
self.name.setText(model["name"])
self.age.setValue(model["age"])
self.icecream.setCurrentText(model["favorite_icecream"])
self.disable_details.setChecked(model["disable_details"])
# Enable/disable fields based on the disable_details state.
# disable_details is True/False, setting setDisabled to True
# disables the field.
self.age.setDisabled(model["disable_details"])
self.icecream.setDisabled(model["disable_details"])
def handle_name_changed(self, name):
model["name"] = name
def handle_age_changed(self, age):
model["age"] = age
def handle_icecream_changed(self, icecream):
model["favorite_icecream"] = icecream
def handle_disable_details(self, checked):
model["disable_details"] = checked
def handle_save_btn(self):
# Save a copy of the current model (if we don't copy,
# changes will modify the backup!)
backups.append(model.copy())
print("SAVE:", model)
print("BACKUPS:", len(backups))
def handle_restore_btn(self):
# Randomly get a backup.
if not backups:
return # Ignore if empty.
random.shuffle(backups)
backup = backups.pop() # Remove a backup.
model.update(backup) # Overwrite the data in the model.
print("RESTORE:", model)
print("BACKUPS:", len(backups))
app = QApplication(sys.argv)
window_a = MainWindow()
window_a.show()
window_b = MainWindow()
window_b.show()
app.exec()