组合框函数currentIndexChanged在pyqt4中无法正常工作

Question

我使用了两个comboBox，即comboBox1和comboBox_2，以及两个函数test和test1，并使用currentIndexChanged（self.comboBOx1.currentIndexChanged和self.comboBOx_2.currentIndexChanged）调用它们。从comboBox1中选择一个值时，将调用其对应的函数（self.comboBOx1.currentIndexChanged），并且对于comboBox_2也是如此。在从comboBox1中选择值时，将更改comboBox_2中的值，并且工作正常。但是我遇到的问题是，首先当我从comboBox1和comboBox_2中选择一个值时，我从调用的函数（打印“ hello”）中获得了预期的值。第二次，当我从comboBox1中选择一个值时，仅应调用测试函数，但此处两个函数（test和test1）均被调用，第二个函数（test1）被调用两次（两次打印“ hello”），第三次它被调用四次（打印“ hello”四次）。请问有人可以帮助我解决这个问题吗？？

代码：

from PyQt4 import QtCore, QtGui

try:
    _fromUtf8 = QtCore.QString.fromUtf8
except AttributeError:
    def _fromUtf8(s):
        return s

try:
    _encoding = QtGui.QApplication.UnicodeUTF8
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig, _encoding)
except AttributeError:
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig)

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName(_fromUtf8("MainWindow"))
        MainWindow.resize(800, 600)
        self.centralwidget = QtGui.QWidget(MainWindow)
        self.centralwidget.setObjectName(_fromUtf8("centralwidget"))
        self.comboBox1 = QtGui.QComboBox(self.centralwidget)
        self.comboBox1.setGeometry(QtCore.QRect(310, 150, 171, 31))
        self.comboBox1.setObjectName(_fromUtf8("comboBox1"))
        self.comboBox1.addItem(_fromUtf8(""))
        self.comboBox1.addItem(_fromUtf8(""))
        self.comboBox1.addItem(_fromUtf8(""))
        self.comboBox1.addItem(_fromUtf8(""))
        self.comboBox_2 = QtGui.QComboBox(self.centralwidget)
        self.comboBox_2.setGeometry(QtCore.QRect(310, 240, 171, 41))
        self.comboBox_2.setObjectName(_fromUtf8("comboBox_2"))
        self.comboBox_2.addItem(_fromUtf8(""))
        self.comboBox_2.addItem(_fromUtf8(""))
        self.comboBox_2.addItem(_fromUtf8(""))
        self.comboBox_2.addItem(_fromUtf8(""))
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtGui.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 21))
        self.menubar.setObjectName(_fromUtf8("menubar"))
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtGui.QStatusBar(MainWindow)
        self.statusbar.setObjectName(_fromUtf8("statusbar"))
        MainWindow.setStatusBar(self.statusbar)

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

    def retranslateUi(self, MainWindow):
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow", None))
        self.comboBox1.setItemText(0, _translate("MainWindow", "select", None))
        self.comboBox1.setItemText(1, _translate("MainWindow", "a", None))
        self.comboBox1.setItemText(2, _translate("MainWindow", "b", None))
        self.comboBox1.setItemText(3, _translate("MainWindow", "c", None))
        self.comboBox_2.setItemText(0, _translate("MainWindow", "select", None))
        self.comboBox_2.setItemText(1, _translate("MainWindow", "p", None))
        self.comboBox_2.setItemText(2, _translate("MainWindow", "q", None))
        self.comboBox_2.setItemText(3, _translate("MainWindow", "r", None))
        self.comboBox_2.setEnabled(0)
        self.comboBox1.currentIndexChanged.connect(self.test)

    def test(self):
        s = str(self.comboBox1.currentText())
        res=['aa','bb','cc','dd']

        if (s == "- - select - -"):
            self.comboBox_2.setEnabled(0)
            self.comboBox_2.setCurrentIndex(0)
        elif(len(s)== 0):
            self.comboBox_2.setEnabled(1)
            self.comboBox_2.clear()
            self.comboBox_2.addItem("- - select - -")
            self.comboBox_2.addItem("New Checklist")
        else:
            self.comboBox_2.setEnabled(1)
            self.comboBox_2.clear()
            self.comboBox_2.addItem("- - select - -")
            self.comboBox_2.addItem("New Checklist")
            self.comboBox_2.addItems(res)
            self.comboBox_2.currentIndexChanged.connect(self.test1)

    def test1(self):
        print ("Hello")

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

Answer 1

要了解其行为，我们将使用以下示例：

示例1 ：

from PyQt4 import QtCore, QtGui


def on_clicked():
    print("clicked")


if __name__ == "__main__":
    import sys

    app = QtGui.QApplication(sys.argv)
    button = QtGui.QPushButton("Press me")
    for _ in range(4):
        button.clicked.connect(on_clicked)
    button.show()
    sys.exit(app.exec_())

当您按下按钮时，它会打印4次，因为Qt不会记住信号和函数之间是否已经存在连接，因此如果同一信号和函数之间存在n个连接，则当tt调用n次时，它们将被调用n次。发出信号。

示例2 ：

from PyQt4 import QtCore, QtGui


def on_currentIndexChanged(ix):
    print("currentIndex:", ix)


if __name__ == "__main__":
    import sys

    app = QtGui.QApplication(sys.argv)
    combo = QtGui.QComboBox()
    print("currentIndex:", combo.currentIndex())
    combo.currentIndexChanged.connect(on_currentIndexChanged)
    button_add = QtGui.QPushButton("Add Items")
    button_add.clicked.connect(lambda: combo.addItems("1 2 3".split()))
    button_clear = QtGui.QPushButton("Clear")
    button_clear.clicked.connect(combo.clear)
    w = QtGui.QWidget()
    lay = QtGui.QVBoxLayout(w)
    for widget in (combo, button_add, button_clear):
        lay.addWidget(widget)
    w.show()
    sys.exit(app.exec_())

QComboBox的默认currentIndex为-1，当您添加项目时，该值将变为currentIndex为0，而当您清洁QComboBox时，currentIndex将恢复为-1。因此，当您添加或清理项目时，会发出currentIndexChanged信号。

---

基于上述内容，我将解释您指出的行为：在QCombobox 1中选择了一个新的currentIndex时，将调用测试方法，并在清理和导入后输入 else 语句。添加您建立的第一个连接的项目，如果现在重复与连接相同的操作，则将两次发出currentIndexChanged信号（一个用于clear（），另一个用于addItems（）），并且您还创建了第二个连接，如果再次重复，信号发出4次（1 clear（）x 2个连接+ 1 addItems（）x 2个连接）。

解决方案：

• 在仅调用一次的函数中建立连接。
• 为使clear（）信号和addItems（）不会发出currentIndexChanged信号，必须使用blockSignals（）。
• 此外，建议不要修改Qt Designer生成的代码，除了使用@ QtCore.pyqtSlot（）装饰外，建议创建另一个使用初始类作为接口的类。 / li>

from PyQt4 import QtCore, QtGui

try:
    _fromUtf8 = QtCore.QString.fromUtf8
except AttributeError:
    def _fromUtf8(s):
        return s

try:
    _encoding = QtGui.QApplication.UnicodeUTF8
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig, _encoding)
except AttributeError:
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig)

class Ui_MainWindow(object):
    def setupUi(self, MainWindow):
        MainWindow.setObjectName(_fromUtf8("MainWindow"))
        MainWindow.resize(800, 600)
        self.centralwidget = QtGui.QWidget(MainWindow)
        self.centralwidget.setObjectName(_fromUtf8("centralwidget"))
        self.comboBox1 = QtGui.QComboBox(self.centralwidget)
        self.comboBox1.setGeometry(QtCore.QRect(310, 150, 171, 31))
        self.comboBox1.setObjectName(_fromUtf8("comboBox1"))
        self.comboBox1.addItem(_fromUtf8(""))
        self.comboBox1.addItem(_fromUtf8(""))
        self.comboBox1.addItem(_fromUtf8(""))
        self.comboBox1.addItem(_fromUtf8(""))
        self.comboBox_2 = QtGui.QComboBox(self.centralwidget)
        self.comboBox_2.setGeometry(QtCore.QRect(310, 240, 171, 41))
        self.comboBox_2.setObjectName(_fromUtf8("comboBox_2"))
        self.comboBox_2.addItem(_fromUtf8(""))
        self.comboBox_2.addItem(_fromUtf8(""))
        self.comboBox_2.addItem(_fromUtf8(""))
        self.comboBox_2.addItem(_fromUtf8(""))
        MainWindow.setCentralWidget(self.centralwidget)
        self.menubar = QtGui.QMenuBar(MainWindow)
        self.menubar.setGeometry(QtCore.QRect(0, 0, 800, 21))
        self.menubar.setObjectName(_fromUtf8("menubar"))
        MainWindow.setMenuBar(self.menubar)
        self.statusbar = QtGui.QStatusBar(MainWindow)
        self.statusbar.setObjectName(_fromUtf8("statusbar"))
        MainWindow.setStatusBar(self.statusbar)

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

    def retranslateUi(self, MainWindow):
        MainWindow.setWindowTitle(_translate("MainWindow", "MainWindow", None))
        self.comboBox1.setItemText(0, _translate("MainWindow", "select", None))
        self.comboBox1.setItemText(1, _translate("MainWindow", "a", None))
        self.comboBox1.setItemText(2, _translate("MainWindow", "b", None))
        self.comboBox1.setItemText(3, _translate("MainWindow", "c", None))
        self.comboBox_2.setItemText(0, _translate("MainWindow", "select", None))
        self.comboBox_2.setItemText(1, _translate("MainWindow", "p", None))
        self.comboBox_2.setItemText(2, _translate("MainWindow", "q", None))
        self.comboBox_2.setItemText(3, _translate("MainWindow", "r", None))


class MainWindow(QtGui.QMainWindow, Ui_MainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.setupUi(self)

        self.comboBox_2.setEnabled(False)
        self.comboBox1.currentIndexChanged[str].connect(self.test)
        self.comboBox_2.currentIndexChanged.connect(self.test1)

    @QtCore.pyqtSlot(str)
    def test(self, s):
        res=['aa','bb','cc','dd']

        if s == "- - select - -":
            self.comboBox_2.setEnabled(False)
            self.comboBox_2.setCurrentIndex(0)
        elif not s:
            self.comboBox_2.setEnabled(True)
            self.comboBox_2.blockSignals(True)
            self.comboBox_2.clear()
            self.comboBox_2.addItem("- - select - -")
            self.comboBox_2.addItem("New Checklist")
            self.comboBox_2.blockSignals(False)
        else:
            self.comboBox_2.setEnabled(True)
            self.comboBox_2.blockSignals(True)
            self.comboBox_2.clear()
            self.comboBox_2.addItem("- - select - -")
            self.comboBox_2.addItem("New Checklist")
            self.comboBox_2.addItems(res)
            self.comboBox_2.blockSignals(False)


    @QtCore.pyqtSlot(int)
    def test1(self, ix):
        print("Hello", ix)

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