使用 QSettings 保存 QRadioButtons 的状态未在 PyQt5 中正确保存值

Question

我对使用 QSettings 将单选按钮的状态从一个应用程序会话保存到另一个使用 PyQt5 的结果感到困惑。 （操作系统 = Ubuntu Linux 18.04）

这些是产生令人困惑的结果的步骤：

1. 运行应用程序；查看选中的两个单选按钮；两个按钮都像鼠标被选中一样触发
2. 取消选择顶部单选按钮
3. 关闭应用程序；查看单选按钮选中状态的“正确”保存
4. 运行应用程序；即使保存了仅选择一个按钮的不同状态，这两个单选按钮也会被选中
5. 取消选择顶部单选按钮
6. 关闭应用程序；查看单选按钮选中状态的“正确”保存
7. 在代码中，第18行，将QSettings('LoneProgrammer2', 'qsettingsTest1')改为QSettings('ChangeThis', 'qsettingsTest1')；保存代码
8. 运行应用程序； !!单选按钮选择反映了正确保存的值！！
9. 关闭应用程序； 10 运行应用程序，现在再次选择了两个单选按钮！

谁能解释一下这里发生了什么？我只是想让 QSettings 工作。

import sys

from PyQt5.QtCore import QSettings
from PyQt5.QtWidgets import QApplication, QWidget, QVBoxLayout, QDialogButtonBox, QGroupBox, QHBoxLayout, QRadioButton


class MyApp(QWidget):
    def __init__(self):
        super().__init__()

        self.oAutoPromoteRadioBtn = QRadioButton("Automatically Promote to Queen")
        self.oAutoPromoteRadioBtn.toggled.connect(self.on_selected)

        self.oUsePopupRadioBtn = QRadioButton("Promote Pawn Using Popup Window")
        self.oUsePopupRadioBtn.toggled.connect(self.on_selected)
        self.oUsePopupRadioBtn.setChecked(True)

        self.settings = QSettings('LoneProgrammer2', 'qsettingsTest1')  # companyname, appname 
        self.settings.beginGroup("Promotion Dialog")
        self.oAutoPromoteRadioBtn.setChecked(
            bool(self.settings.value('auto-promote radio button checked state')))
        self.oUsePopupRadioBtn.setChecked(
            bool(self.settings.value('promote using popup radio button checked state')))
        self.settings.endGroup()
        print('AT APP OPENING:')
        print('self.oAutoPromoteRadioBtn.isChecked() = ', self.oAutoPromoteRadioBtn.isChecked())
        print('self.oUsePopupRadioBtn.isChecked() = ', self.oUsePopupRadioBtn.isChecked())

        oVertLayoutForRadioButtons = QVBoxLayout()
        oVertLayoutForRadioButtons.addWidget(self.oAutoPromoteRadioBtn)
        oVertLayoutForRadioButtons.addWidget(self.oUsePopupRadioBtn)

        self.groupbox = QGroupBox("Select pawn promotion method:")
        self.groupbox.setFixedWidth(300)
        self.groupbox.setFixedHeight(95)
        self.groupbox.setLayout(oVertLayoutForRadioButtons)

        self.oVertLayout = QVBoxLayout()
        self.oVertLayout.addWidget(self.groupbox)
        self.setLayout(self.oVertLayout)

    def on_selected(self):
        radio_button = self.sender()

        if radio_button.isChecked():
            if radio_button.text() == 'Automatically Promote to Queen':
                print('set to auto-promote to queen')
            elif radio_button.text() == 'Promote Pawn Using Popup Window':
                print('set to promote pawn to queen using popup window')

    def closeEvent(self, event):
        # save the vars from this session
        self.settings.beginGroup("Promotion Dialog")
        self.settings.setValue('auto-promote radio button checked state', self.oAutoPromoteRadioBtn.isChecked())
        self.settings.setValue('promote using popup radio button checked state', self.oUsePopupRadioBtn.isChecked())
        self.settings.endGroup()

        print()
        print('AT APP CLOSE:')
        print('self.oAutoPromoteRadioBtn.isChecked() = ', self.oAutoPromoteRadioBtn.isChecked())
        print('self.oUsePopupRadioBtn.isChecked() = ', self.oUsePopupRadioBtn.isChecked())


if __name__ == "__main__":
    app = QApplication(sys.argv)

    demo = MyApp()
    demo.show()
    sys.exit(app.exec_())

Answer 1

在读取设置值时最好指出类型，因为可能会造成混淆（最有可能的值将返回字符串“true”和“false”，在使用 bool 时转换为 True，因为它们是真的）。另一方面，为了增加可读性，最好创建专门的方法。

from functools import cached_property
import sys

from PyQt5.QtCore import QSettings
from PyQt5.QtWidgets import (
    QApplication,
    QWidget,
    QVBoxLayout,
    QDialogButtonBox,
    QGroupBox,
    QHBoxLayout,
    QRadioButton,
)


class MyApp(QWidget):
    def __init__(self):
        super().__init__()

        self.oAutoPromoteRadioBtn = QRadioButton("Automatically Promote to Queen")
        self.oAutoPromoteRadioBtn.toggled.connect(self.on_selected)

        self.oUsePopupRadioBtn = QRadioButton("Promote Pawn Using Popup Window")
        self.oUsePopupRadioBtn.toggled.connect(self.on_selected)

        self.settings = QSettings(
            "LoneProgrammer2", "qsettingsTest1"
        )  # companyname, appname

        oVertLayoutForRadioButtons = QVBoxLayout()
        oVertLayoutForRadioButtons.addWidget(self.oAutoPromoteRadioBtn)
        oVertLayoutForRadioButtons.addWidget(self.oUsePopupRadioBtn)

        self.groupbox = QGroupBox("Select pawn promotion method:")
        self.groupbox.setFixedSize(300, 95)
        self.groupbox.setLayout(oVertLayoutForRadioButtons)

        self.oVertLayout = QVBoxLayout(self)
        self.oVertLayout.addWidget(self.groupbox)

        self.read_settings()

    def on_selected(self):
        radio_button = self.sender()

        if radio_button.isChecked():
            if radio_button.text() == "Automatically Promote to Queen":
                print("set to auto-promote to queen")
            elif radio_button.text() == "Promote Pawn Using Popup Window":
                print("set to promote pawn to queen using popup window")

    @cached_property
    def settings(self):
        return QSettings("LoneProgrammer2", "qsettingsTest1")

    @property
    def mapping_settings(self):
        return {
            "Promotion Dialog": [
                ("auto-promote radio button checked state", self.oAutoPromoteRadioBtn),
                (
                    "promote using popup radio button checked state",
                    self.oUsePopupRadioBtn,
                ),
            ]
        }

    def read_settings(self):
        for group_key, values in self.mapping_settings.items():
            self.settings.beginGroup(group_key)
            for (key, checkbox) in values:
                value = self.settings.value(key, type=bool)
                checkbox.setChecked(value)
            self.settings.endGroup()

    def write_settings(self):
        for group_key, values in self.mapping_settings.items():
            self.settings.beginGroup(group_key)
            for (key, checkbox) in values:
                self.settings.setValue(key, checkbox.isChecked())
            self.settings.endGroup()

    def closeEvent(self, event):
        super().closeEvent(event)
        self.write_settings()


if __name__ == "__main__":
    app = QApplication(sys.argv)

    demo = MyApp()
    demo.show()
    sys.exit(app.exec_())