python - 如何从 QDialog 访问 QMainWindow 中的小部件

Question

在发布我的问题之前，我进行了很多搜索，发现了一些可能相似但无法解决我的问题的问题。我相信这很容易，但我不知道怎么做:

下面是问题的一个最小示例:

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        #MainWindow.setObjectName("MainWindow")
        MainWindow.setEnabled(True)
        MainWindow.resize(574, 521)
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        self.verticalLayout_2 = QtWidgets.QVBoxLayout(self.centralwidget)
        self.firstPushButton = QtWidgets.QPushButton(self.centralwidget)
        self.firstLineEdit = QtWidgets.QLineEdit(self.centralwidget)
        self.firstPushButton.clicked.connect(self.showDialog)

        # the other stuff related to layout setup is ommited

    def showDialog(self):
        dialog = MyDialog(MainWindow)
        dialog.exec()

class MyDialog(QtWidgets.QDialog):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.setFixedSize(400, 200)
        self.myButton = QtWidgets.QPushButton("Write something")
        # When I click the myButton, I want it to change the text of MainWindow lineEdit
        self.myButton.clicked.connect(self.writeHello)

    def writeHello(self):
      # How can I access firstLineEdit from MainWindow? I want to write "Hello" to the firstLineEdit
      pass

if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    MainWindow = QtWidgets.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.setWindowTitle("BEM Analysis for propellers")
    MainWindow.show()
    sys.exit(app.exec())

你能告诉我如何实现 writeHello() 方法以便在 MainWindow 的 firstLineEdit 中写一些东西吗

谢谢

Answer 1

首先，您不应该修改 Qt Designer 生成的代码，因为它不是 GUI，它只是一个填充 GUI 的类，并且会带来一些不便，例如无法覆盖小部件的方法，或者一些您想在该类中使用小部件的方法。相反，它继承自合适的小部件并使用其他类作为接口(interface)。

说到你不应该混合类，因为它们之间会有很多依赖关系，将来如果你修改一个类，你将不得不修改另一个，这是无与伦比的，而不是你使用信号来通知任何更改或操作。

from PyQt5 import QtCore, QtGui, QtWidgets

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        #MainWindow.setObjectName("MainWindow")
        MainWindow.setEnabled(True)
        MainWindow.resize(574, 521)
        MainWindow.setWindowIcon(QtGui.QIcon(':/icons/drone.ico'))
        MainWindow.setIconSize(QtCore.QSize(32, 32))
        self.centralwidget = QtWidgets.QWidget(MainWindow)
        MainWindow.setCentralWidget(self.centralwidget)
        self.verticalLayout_2 = QtWidgets.QVBoxLayout(self.centralwidget)
        self.firstPushButton = QtWidgets.QPushButton(self.centralwidget)
        self.firstLineEdit = QtWidgets.QLineEdit(self.centralwidget)
        self.verticalLayout_2.addWidget(self.firstPushButton)
        self.verticalLayout_2.addWidget(self.firstLineEdit)

class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.setupUi(self)
        self.firstPushButton.clicked.connect(self.showDialog)

    def showDialog(self):
        dialog = MyDialog()
        dialog.clicked.connect(self.writeHello)
        dialog.exec()

    @QtCore.pyqtSlot()
    def writeHello(self):
        self.firstLineEdit.setText('Hello')

class MyDialog(QtWidgets.QDialog):
    clicked = QtCore.pyqtSignal()

    def __init__(self, parent=None):
        super().__init__(parent)
        self.setFixedSize(400, 200)
        self.myButton = QtWidgets.QPushButton("Write something")
        # When I click the myButton, I want it to change the text of MainWindow lineEdit
        self.myButton.clicked.connect(self.clicked)
        lay = QtWidgets.QVBoxLayout(self)
        lay.addWidget(self.myButton)

if __name__ == "__main__":
    import sys
    app = QtWidgets.QApplication(sys.argv)
    w = MainWindow()
    w.setWindowTitle("BEM Analysis for propellers")
    w.show()
    sys.exit(app.exec())