Qt Python Combo-Box "currentIndexChanged" firing twice

Question

I have a combo, which is showing some awkward behavior. Given a list of options from the combo-box, the user should pick the name of a city clicking with the mouse. Here is the code:

QtCore.QObject.connect(self.comboCity, QtCore.SIGNAL("currentIndexChanged(QString)"), self.checkChosenCity)                 

def checkChosenCity(self):
    self.cityName=self.comboCity.currentText()
    print "the city chosen is:"
    print "%s" % self.cityName

The problem is, each time a city is chosen, connect calls the function checkChosenCity twice.

This combo is a hierarchical combo, i.e. after in the first combo a customer is chosen, then in the second combo-box comes the list of cities for that customer.

I hope someone here can point out or guess why this is happening.

Answer 1

Thanks Eli..

Here is what I have:

combo1 : [customernames] - pick a customer.
combo2 : [cityList] - pick a city for the chosen customer.
combo3 : [emploeeList] - load employees for that city, given the chosen customer.

What I find out is that, even when no city is chosen, the combox-box for city is activated. And yes, I have checked if the function 'checkChosenCity' is not called anywhere else inside the program.

As a quick fix, not the ideal solution, I put a condition to avoid the problem into the function 'checkChosenCity'. So, now when this function is wrongly activated by 'connect', it checks if a city name was really selected, if none, then the pointed process doesn't run avoiding the system to crash.

Here is the function that loads the city list into combo-box:

def loadcomboCity(self,customerName):
    if customerName == " ": 
        """no customer was chosen yet - list of city empty"""
     id=0
        CityName=" "
        self.addcomboCity(id,CityName)
    else:
        """for this customerName - load his city list"""
        self.loadCityList_mysql(customerName)

     lin=0
     """ the data is imported from mysql class into self.db.matrix"""
        for row in self.db.matrix:
            id=lin
            cityname=self.db.matrix[lin][0]
            print "city name = %s" % cityname
            self.addcomboCity(id,cityname) 
            lin=lin+1

Here is the function that loads the customer-names list into combo-box:

def loadComboCustomer(self):
    """queries customerList into self.connexDB.matrix"""
    self.loadCustomerList_mysql()

    lin=0
    """ the data is imported from mysql class into self.db.matrix"""
    for row in self.connexDB.matrix:
        id=lin
        customername=self.connexDB.matrix[lin][0]
        self.addcomboCustomer(id,customername)  
        lin=lin+1

Here is the function that checkes if the a customer name was chosen:

def checkChosenCustomer(self):
    self.customerName=self.comboCustomer.currentText()
    print "the customer chosen is:"
    print "%s" % self.customerName

    self.loadcomboCity(self.customerName)

Here is the function that checks if some city chosen from list into combo-box:

def checkChosenCity(self):
    self.CityName=self.comboCity.currentText()
    print "the City chosen is:"
    print "value of City = %s" % self.CityName

    if self.CityName == '':
        print "empty"
    else:
        """for this city - load the respective customer employee list"""
        self.buildListOfEmployees_mysql(self.CityName)

     """ the data is imported from mysql class into self.db.matrix"""
        for row in self.db.matrix:
            id=lin+1
            personname=self.db.matrix[lin][0]
            print "person name = %s" % personname
            self.addcomboPerson(id,personname) 
            lin=lin+1

Here is the main function that connect combo-box events:

def options(self):
    self.comboCustomer = QtGui.QComboBox(self.boxBooking)
    self.comboCustomer.setGeometry(QtCore.QRect(60, 60, 521, 22))

    self.loadComboCustomer()
    QtCore.QObject.connect(self.comboCustomer, QtCore.SIGNAL("currentIndexChanged(QString)"), self.checkChosenCustomer)

    self.comboCity = QtGui.QComboBox(self.boxBooking)
    self.comboCity.setGeometry(QtCore.QRect(60, 120, 521, 22))

    self.loadcomboCity(self.customerName)
    QtCore.QObject.connect(self.comboCity, QtCore.SIGNAL("currentIndexChanged(QString)"), self.checkChosenCity)

Not the ideal solution really. But, quite funny to have to spend hours to find out that such a strange connect event is being wrongly self-activated.

If you discover any other explanation, just let us know.

Answer 2

I had exactly the same problem. After some debugging it turned out that using

currentIndexChanged(int)

instead of

currentIndexChanged(QString)

fixed it for me.

It still don't understand why the former fires twice.

Answer 3

With regard to why currentIndexChanged(int) works and currentIndexChanged(QString) doesn't, I believe you would have had to use:

currentIndexChanged(const QString&)

instead.

EDIT: This comment is directed at user469276 below...