PyQT : How to activate a command link button when at least one element of treeview is checked ?

[A Former User]

Hello,
I want to activate command link button if at least one element is checked in a treeview.

I tried this method but it is not working well :

def activate_launch_button(self):

    model = self.scenarios.model()
    checked_indexes = model.match(model.index(0, 0), QtCore.Qt.CheckStateRole,QtCore.Qt.Checked, -1,QtCore.Qt.MatchExactly | QtCore.Qt.MatchRecursive)
    print checked_indexes
    if checked_indexes != []:
        self.launch_btn.setEnabled(True)

The problem with this method is the button is activated only after closing the window. I don't understand why. For caling this method I put it in two methods :

def show(self):
    self.project.load()
    if self.project.tranus_project:
        self.tranus_folder.setText(self.project.tranus_project.path)
    self.activate_launch_button()
    self.launch_options_TRANUS()
    super(OptionsTRANUSDialog, self).show()

def select_tranus_folder(self):

    folder = QtGui.QFileDialog.getExistingDirectory(self, "Select directory")
    if folder:
        self.tranus_folder.setText(folder)
        if not self.project.load_tranus_folder(folder):
            self.tranus_folder.setText('')
        self.reload_scenarios()
        self.activate_launch_button()

I really want that the command link button should be activated when at least one element of treeview is checked and to be inactive if there is no element checked.

Thanks.

[jsulm]

@EJWA Connect a slot to http://doc.qt.io/qt-5/qabstractitemview.html#activated and call your function there

[VRonin]

I'm awful at Python so I'll just describe what I'd do.

• add an integer private variable to the class that counts the items checked and initialise to 0 (int countCheck=0;).
• define a role that will save previous check information (probably something like Qt::UserRole + Qt::CheckStateRole)
• connect a slot to the dataChanged signal of the model
• in the slot put something like (sorry if it's C++)

void dataChangedSlot(const QModelIndex& index){
if(index.data(Qt::CheckStateRole).toInt() != index.data(Qt::UserRole + Qt::CheckStateRole).toInt()){
if(index.data(Qt::CheckStateRole).toInt()!=Qt::Unchecked){
++countCheck;
model->setData(index,index.data(Qt::CheckStateRole),Qt::UserRole + Qt::CheckStateRole);
}
else{
--countCheck;
model->setData(index,QVariant(),Qt::UserRole + Qt::CheckStateRole);
}
launch_btn->setEnabled(countCheck>0);
}
}

[A Former User]

@jsulm Hello, thank you for your reply.

I am sorry but my item is a QStandardItem so I cannot use the method activated of QAbstractItemView.

[A Former User]

Finally, I found a partial solution to my problem, I used the signal itemChanged http://pyqt.sourceforge.net/Docs/PyQt4/qstandarditemmodel.html#itemChanged

def activate_launch_button(self):

    model = self.scenarios.model()
    model.itemChanged.connect(self.check_configure)

def check_configure(self):
    self.launch_btn.setEnabled(True)

It activates the button when there is one element is checked however when I uncheck all, the button doesn't become inactive. How can I solve this issue ?

[SGaist]

Hi,

Do it like @VRonin suggested. Keep a counter and increment/decrement it when an item is changed.

[A Former User]

Hello,

Sorry, but I dont' understand really C++. If I understand, I must redefine the method setData ??

I will try to understand.

[A Former User]

Final solution, it works very well. Thanks to @SGaist and @VRonin :

def activate_launch_button(self):

    model = self.scenarios.model()
    model.itemChanged.connect(self.check_configure)
def check_configure(self,item):

        model = self.scenarios.model()
        index = model.indexFromItem(item)

        if index.data(QtCore.Qt.CheckStateRole) != index.data(QtCore.Qt.UserRole + QtCore.Qt.CheckStateRole):

            if index.data(QtCore.Qt.CheckStateRole)!= QtCore.Qt.Unchecked :

                self.count_check+=1
                model.setData(index,index.data(QtCore.Qt.CheckStateRole),QtCore.Qt.UserRole + QtCore.Qt.CheckStateRole)

            else :

                self.count_check-=1
                model.setData(index,index.data(QtCore.Qt.CheckStateRole),QtCore.Qt.UserRole + QtCore.Qt.CheckStateRole)
                print self.count_check

            self.launch_btn.setEnabled(self.count_check>0)