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

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);
}
}

@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.

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.

Hello,

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

I will try to understand.

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)

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