使用子类对话框窗口中的方法影响主窗口的问题答案

【问题标题】：Problems using method in subclass dialog window to affect main window使用子类对话框窗口中的方法影响主窗口的问题
【发布时间】：2019-05-27 00:25:48
【问题描述】：

我正在尝试使用 PyQT5 创建一个 GUI 程序。我是编程和 Python 新手，所以如果我以错误的方式解释事情，请纠正我。

我有一个主窗口，其中包含多个 QLineEdit 小部件和相应的“清除”按钮，用于清除用户输入的数据。主窗口还包含“编辑”按钮，用于显示特定对话框，也可以在其中编辑数据。我的示例有一个“用户 ID”QLineEdit 小部件/文本框、“清除”和“编辑”按钮。

单击“编辑”时出现的对话框有自己的“清除”按钮。如果单击对话框窗口中的清除按钮，则对话框和主窗口中的 QLineEdit 小部件都应被清除。

问题： 当我从对话框类继承主窗口类时，用于清除用户 ID 字段的方法 clearUserID() 调用失败。

当我不从主窗口类继承 clearUserID 方法时，我能够清除对话框 QLineEdit (UserIDWin_UserID_lnedt)但不能主窗口上的相应小部件 (UserID_lnedt)。我尝试使用对话框“清除”按钮清除主窗口 QLineEdit 小部件的所有代码导致我的程序崩溃。

有人能帮我更好地理解这些原则背后的逻辑以及如何让我的代码正常工作吗？谢谢。

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(820, 611)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.tabWidget = QtWidgets.QTabWidget(self.centralwidget)
        self.tabWidget.setGeometry(QtCore.QRect(0, 0, 801, 551))
        self.tabWidget.setObjectName("tabWidget")
        self.MainTab = QtWidgets.QWidget()
        self.MainTab.setObjectName("MainTab")
        self.UserID_Edit_pb = QtWidgets.QPushButton(self.MainTab)
        self.UserID_Edit_pb.setGeometry(QtCore.QRect(210, 10, 31, 23))
        self.UserID_Edit_pb.setObjectName("UserID_Edit_pb")
        self.UserID_Edit_pb.clicked.connect(self.openUserIDWin)
        self.UserID_Clear_pb_2 = QtWidgets.QPushButton(self.MainTab)
        self.UserID_Clear_pb_2.setGeometry(QtCore.QRect(170, 9, 41, 23))
        self.UserID_Clear_pb_2.setObjectName("UserID_Clear_pb_2")
        self.UserID_le = QtWidgets.QLineEdit(self.MainTab)
        self.label = QtWidgets.QLabel(self.MainTab)
        self.label.setGeometry(QtCore.QRect(10, 10, 47, 13))
        self.UserID_le.setGeometry(QtCore.QRect(50, 10, 113, 20))
        self.UserID_le.setObjectName("UserID_le")
        self.tabWidget.addTab(self.MainTab, "")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 820, 21))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        self.tabWidget.setCurrentIndex(0)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

        self.UserID_Clear_pb_2.clicked.connect(self.UserID_le.clear)


    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.UserID_Edit_pb.setText(_translate("MainWindow", "Edit"))
        self.UserID_Clear_pb_2.setText(_translate("MainWindow", "Clear"))
        self.label.setText(_translate("MainWindow", "User ID"))
        self.tabWidget.setTabText(self.tabWidget.indexOf(self.MainTab), _translate("MainWindow", "Tab"))

    def openUserIDWin(self):
        UserID_value = self.UserID_le.text()
        UserIDWin = QtWidgets.QDialog()
        ui = Ui_UserIDWin(UserID_value)
        ui.setupUi(UserIDWin)
        UserIDWin.exec_();



class Ui_UserIDWin(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self, userID):
        print("The User ID is:" + userID)
        self.userID = userID

    def setupUi(self, UserIDWin):
        UserIDWin.setObjectName("UserIDWin")
        UserIDWin.resize(400, 124)
        self.UserIDWin_UserID_lnedt = QtWidgets.QLineEdit(UserIDWin)
        self.UserIDWin_UserID_lnedt.setText(self.userID)
        self.UserIDWin_UserID_lnedt.setGeometry(QtCore.QRect(20, 50, 113, 20))
        self.UserIDWin_UserID_lnedt.setObjectName("UserIDWin_UserID_lnedt")
        self.UserIDWin_UserID_lbl = QtWidgets.QLabel(UserIDWin)
        self.UserIDWin_UserID_lbl.setGeometry(QtCore.QRect(20, 30, 47, 13))
        self.UserIDWin_UserID_lbl.setObjectName("UserIDWin_UserID_lbl")
        self.UserIDWin_UserIDClear_pushb = QtWidgets.QPushButton(UserIDWin)
        self.UserIDWin_UserIDClear_pushb.setGeometry(QtCore.QRect(140, 50, 41, 23))
        self.UserIDWin_UserIDClear_pushb.setObjectName("UserIDWin_UserIDClear_pushb")
        self.UserIDWin_Cancel_pushb = QtWidgets.QPushButton(UserIDWin)
        self.UserIDWin_Cancel_pushb.setGeometry(QtCore.QRect(110, 80, 75, 23))
        self.UserIDWin_Cancel_pushb.setObjectName("UserIDWin_Cancel_pushb")
        self.UserIDWin_Next_pushb = QtWidgets.QPushButton(UserIDWin)
        self.UserIDWin_Next_pushb.setGeometry(QtCore.QRect(190, 80, 75, 23))
        self.UserIDWin_Next_pushb.setObjectName("UserIDWin_Next_pushb")

        self.retranslateUi(UserIDWin)
        QtCore.QMetaObject.connectSlotsByName(UserIDWin)

        #If I do not inherit from "QtWidgets.QMainWindow, Ui_MainWindow" the code below works and invokes clearUserId().  However, I then am having problems using SetText on the main window UserId_le text box and the program crashes.
        self.UserIDWin_UserIDClear_pushb.clicked.connect(self.clearUserID)

    def retranslateUi(self, UserIDWin):
        _translate = QtCore.QCoreApplication.translate
        UserIDWin.setWindowTitle(_translate("UserIDWin", "Dialog"))
        self.UserIDWin_UserID_lbl.setText(_translate("UserIDWin", "User ID"))
        self.UserIDWin_UserIDClear_pushb.setText(_translate("UserIDWin", "Clear"))
        self.UserIDWin_Cancel_pushb.setText(_translate("UserIDWin", "Cancel"))
        self.UserIDWin_Next_pushb.setText(_translate("UserIDWin", "Next"))

    def clearUserID(self):
        self.UserIDWin_UserID_lnedt.setText('')
        # The line below crashes my program if I am able to invoke this method.
        #self.Ui_MainWindow.UserID_le.setText('')

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

【问题讨论】：

标签： python pyqt pyqt5 qt-designer qdialog

【解决方案1】：

他们似乎对继承和良好实践有一些明确的概念，但其他人不喜欢以下内容：

PyQt 建议不要修改 Qt Designer 生成的代码，因为您将来可能想要修改 GUI，并且在使用 pyuic 时初始代码会被覆盖。另一个问题是初学者不明白Qt Designer生成的类不是一个widget，而是一个用来填充另一个widget的接口，因此除了其他问题外，不能覆盖widget的方法。
如果两者具有相同的范围，您只需从另一个类的对象修改一个类的对象，在您的情况下，如果想要从另一个窗口清除主窗口的 QLineEdit 是一项危险的任务，相反，您应该在两个窗口具有相同范围并且在 openUserIDWin 方法中的情况下执行该逻辑。
QLineEdit 已经有 clear() 方法可以进行清理，它实现了与 setText("") 相同的功能，但第一种方法更具可读性。

综合以上，解决办法是：

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName("MainWindow")
        MainWindow.resize(820, 611)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.centralwidget.setObjectName("centralwidget")
        self.tabWidget = QtWidgets.QTabWidget(self.centralwidget)
        self.tabWidget.setGeometry(QtCore.QRect(0, 0, 801, 551))
        self.tabWidget.setObjectName("tabWidget")
        self.MainTab = QtWidgets.QWidget()
        self.MainTab.setObjectName("MainTab")
        self.UserID_Edit_pb = QtWidgets.QPushButton(self.MainTab)
        self.UserID_Edit_pb.setGeometry(QtCore.QRect(210, 10, 31, 23))
        self.UserID_Edit_pb.setObjectName("UserID_Edit_pb")
        self.UserID_Clear_pb_2 = QtWidgets.QPushButton(self.MainTab)
        self.UserID_Clear_pb_2.setGeometry(QtCore.QRect(170, 9, 41, 23))
        self.UserID_Clear_pb_2.setObjectName("UserID_Clear_pb_2")
        self.UserID_le = QtWidgets.QLineEdit(self.MainTab)
        self.label = QtWidgets.QLabel(self.MainTab)
        self.label.setGeometry(QtCore.QRect(10, 10, 47, 13))
        self.UserID_le.setGeometry(QtCore.QRect(50, 10, 113, 20))
        self.UserID_le.setObjectName("UserID_le")
        self.tabWidget.addTab(self.MainTab, "")
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtWidgets.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 820, 21))
        self.menubar.setObjectName("menubar")
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtWidgets.QStatusBar(MainWindow)
        self.statusbar.setObjectName("statusbar")
        MainWindow.setStatusBar(self.statusbar)

        self.retranslateUi(MainWindow)
        self.tabWidget.setCurrentIndex(0)
        QtCore.QMetaObject.connectSlotsByName(MainWindow)

    def retranslateUi(self, MainWindow):
        _translate = QtCore.QCoreApplication.translate
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow"))
        self.UserID_Edit_pb.setText(_translate("MainWindow", "Edit"))
        self.UserID_Clear_pb_2.setText(_translate("MainWindow", "Clear"))
        self.label.setText(_translate("MainWindow", "User ID"))
        self.tabWidget.setTabText(self.tabWidget.indexOf(self.MainTab), _translate("MainWindow", "Tab"))


class Ui_UserIDWin(object):
    def setupUi(self, UserIDWin):
        UserIDWin.setObjectName("UserIDWin")
        UserIDWin.resize(400, 124)
        self.UserIDWin_UserID_lnedt = QtWidgets.QLineEdit(UserIDWin)
        self.UserIDWin_UserID_lnedt.setGeometry(QtCore.QRect(20, 50, 113, 20))
        self.UserIDWin_UserID_lnedt.setObjectName("UserIDWin_UserID_lnedt")
        self.UserIDWin_UserID_lbl = QtWidgets.QLabel(UserIDWin)
        self.UserIDWin_UserID_lbl.setGeometry(QtCore.QRect(20, 30, 47, 13))
        self.UserIDWin_UserID_lbl.setObjectName("UserIDWin_UserID_lbl")
        self.UserIDWin_UserIDClear_pushb = QtWidgets.QPushButton(UserIDWin)
        self.UserIDWin_UserIDClear_pushb.setGeometry(QtCore.QRect(140, 50, 41, 23))
        self.UserIDWin_UserIDClear_pushb.setObjectName("UserIDWin_UserIDClear_pushb")
        self.UserIDWin_Cancel_pushb = QtWidgets.QPushButton(UserIDWin)
        self.UserIDWin_Cancel_pushb.setGeometry(QtCore.QRect(110, 80, 75, 23))
        self.UserIDWin_Cancel_pushb.setObjectName("UserIDWin_Cancel_pushb")
        self.UserIDWin_Next_pushb = QtWidgets.QPushButton(UserIDWin)
        self.UserIDWin_Next_pushb.setGeometry(QtCore.QRect(190, 80, 75, 23))
        self.UserIDWin_Next_pushb.setObjectName("UserIDWin_Next_pushb")

        self.retranslateUi(UserIDWin)
        QtCore.QMetaObject.connectSlotsByName(UserIDWin)

    def retranslateUi(self, UserIDWin):
        _translate = QtCore.QCoreApplication.translate
        UserIDWin.setWindowTitle(_translate("UserIDWin", "Dialog"))
        self.UserIDWin_UserID_lbl.setText(_translate("UserIDWin", "User ID"))
        self.UserIDWin_UserIDClear_pushb.setText(_translate("UserIDWin", "Clear"))
        self.UserIDWin_Cancel_pushb.setText(_translate("UserIDWin", "Cancel"))
        self.UserIDWin_Next_pushb.setText(_translate("UserIDWin", "Next"))


class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.setupUi(self)
        self.UserID_Edit_pb.clicked.connect(self.openUserIDWin)
        self.UserID_Clear_pb_2.clicked.connect(self.UserID_le.clear)

    def openUserIDWin(self):
        UserID_value = self.UserID_le.text()
        w = UserIDWin(UserID_value)
        w.UserIDWin_UserIDClear_pushb.clicked.connect(self.UserID_le.clear)
        w.exec_()


class UserIDWin(QtWidgets.QDialog, Ui_UserIDWin):
    def __init__(self, userID, parent=None):
        super(UserIDWin, self).__init__(parent)
        self.setupUi(self)
        self.userID = userID
        self.UserIDWin_UserID_lnedt.setText(self.userID)
        self.UserIDWin_UserIDClear_pushb.clicked.connect(self.UserIDWin_UserID_lnedt.clear)


if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    w = MainWindow()
    w.show()
    sys.exit(app.exec_())

我建议你阅读：

【讨论】：

非常感谢。这个例子为我提供了一个很好的框架来正确学习 PyQT。您对我的代码的修改也帮助我更好地理解了继承以及如何正确使用它。前两个类创建 UI，后两个类控制它们背后的逻辑。 UserID_vaue 变量首先在 MainWindow 类中创建，并在创建时传递给 UserIDWin 类。当单击对话框“清除”按钮时，UserIDWin 类的 init 方法会清除它自己的 QLineEdit，而 MainWindow > openUserIDWin 方法会清除 MainWindow UserID 值。