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Setting up QStackedWidget properly, signal cannot see function/slot

I am working on developing a GUI with PyQt5. This is my first step into OOP, and I'm trying to teach myself as I go. I'm struggling with understanding when classes inherit methods/attributes etc and what methods they have available -- I guess it is a scope-related question? I have produced a MWE to my GUI below. In total, there will be many more pages and signals/slots.
What I want:
The stack should initialize with the "MainMenu" widget/object showing (left image below). Clicking on "Next Page" button should switch the stack order to put the "OtherPage" widget/object on top (right image below). I am creating each page as a class, thinking this would be a good way to organize my project. Is this good or bad practice?
What happens now:
The GUI works (initializes) if the line nextPg.clicked.connect(self.drawOtherPage()) is commented out, but of course then clicking on the button does nothing. I can switch the initial stack order so that "other" widget is on top of the stack and it shows up fine, so I think that class is also working. When the above line is included in the code, the following error is thrown:
in __init__
nextPg.clicked.connect(self.drawOtherPage())
AttributeError: 'MainMenu' object has no attribute 'drawOtherPage'
What I've tried
I thought that the call to super() was supposed to allow the child class (in this case MainMenu) to inherit the methods from the parent class (RootInit). Therefore, I would think this should make the drawOtherPage method available to the button connect signal. Obviously, the error isa result of the method not being available.
What am I doing wrong? Should I be creating these "page" widgets in methods instead? Do they need to be under the RootInit class or can they live in the top level of the .py file? I'm trying to follow best practices as the project will become pretty large in the end. Fortunately, most of it should be pages with variations based on what buttons were clicked to get there -- I therefore thought classes would be helpful. Please be harsh on the code and my python/PyQt vernacular, trying to learn -- thanks!
import sys, os
from PyQt5.QtWidgets import *
from PyQt5 import QtGui, QtCore
class RootInit(QMainWindow):
# root window
def __init__(self, parent=None):
QMainWindow.__init__(self)
self.root = QWidget()
self.stack = QStackedWidget()
rootLayout = QVBoxLayout()
rootLayout.addWidget(self.stack)
self.root.setLayout(rootLayout)
self.setCentralWidget(self.root)
self.initializeGUI()
def initializeGUI(self):
self.main = MainMenu(self) # build MainMenu (class)
self.other = OtherPage(self) # build OtherPage (class)
self.stack.addWidget(self.main)
self.stack.addWidget(self.other)
def drawMain(self):
self.stack.setCurrentIndex(0)
def drawOtherPage(self):
self.stack.setCurrentIndex(1)
class MainMenu(QWidget):
# class for main menu
def __init__(self, parent=None):
QWidget.__init__(self, parent)
super().__init__()
mainLayout = QGridLayout() # layout for entire main menu
quitBtn = QPushButton("Quit")
quitBtn.clicked.connect(QtCore.QCoreApplication.instance().quit)
nextPg = QPushButton("Next page")
nextPg.clicked.connect(self.drawOtherPage())
mainLayout.addWidget(quitBtn, 0, 0)
mainLayout.addWidget(nextPg, 0, 1)
self.setLayout(mainLayout)
class OtherPage(QWidget):
# class for another menu
def __init__(self, parent=None):
QWidget.__init__(self, parent)
label = QLabel("test label")
layout = QGridLayout() #
layout.addWidget(label, 0, 0)
self.setLayout(layout)
if __name__ == '__main__':
app = QApplication(sys.argv)
root = RootInit()
root.setWindowTitle("Title")
root.show()
sys.exit(app.exec_())

Your code has the following errors:
The variable self refers to the same instance of the class, in your case self refers to an instance of MainMenu, and if we observe MainMenu it does not have any drawOtherPage() method.
Another mistake in your case is to call the parent's constructor twice:
class MainMenu(QWidget):
# class for main menu
def __init__(self, parent=None):
QWidget.__init__(self, parent)
super().__init__()
In the first constructor you are assigning a parent, and in the second, you are not. To clarify in python there are several ways to call the parent's constructor:
QWidget.__init__(self, parent)
super(MainMenu, self).__init__(parent)
super().__init__(parent)
so you should only use one of them.
Another error is that a signal is connected through the name of a function, the function must not be evaluated using parentheses
and for the last use of functions or methods that involve several objects should be done in a place where both objects can access, in your case you can take advantage of what you are going to RootInit as parent of MainMenu: self.main = MainMenu(self), and access the connection to that element through the method parent().
All of the above entails modifying the MainMenu class to the following:
class MainMenu(QWidget):
def __init__(self, parent=None):
QWidget.__init__(self, parent)
mainLayout = QGridLayout() # layout for entire main menu
quitBtn = QPushButton("Quit")
quitBtn.clicked.connect(QtCore.QCoreApplication.instance().quit)
nextPg = QPushButton("Next page")
nextPg.clicked.connect(self.parent().drawOtherPage)
mainLayout.addWidget(quitBtn, 0, 0)
mainLayout.addWidget(nextPg, 0, 1)
self.setLayout(mainLayout)

PyQt - access data of another interface?

I have a python script with 2 classes, each one is a different PyQt interface.
The first one is the main interface, and the second one is a "pop-up interface" - it appears when you click a button in the main interface.
Whenever that pop-up interface is launched via the main interface, i need it to display data coming from the main interface.
How can i do that if they're both in different classes?
For example, main interface:
class MainUI(QtGui.QWidget):
def __init__(self):
super(QtGui.QWidget, self).__init__()
self.myData = "data"
pop-up interface:
class PopUp(QtGui.QDialog):
def __init__(self, parent=None):
super(MyDialog, self).__init__(parent)
# some stuff here
Thanks!

Just pass the data into the constructor for PopUp
class PopUp(QtGui.QDialog):
def __init__(self, data, parent=None):
super(MyDialog, self).__init__(parent)
self.data = data
If this is not feasible due to the design of your project, you can use Signals and Slots to pass the data between classes.

Opening a QDialog and saving last state

I am trying to open a QDialog from a QMainWindow, and after closing the `QDialog, if I need to open it again, it has to open and show the same information that had when I close it.
Here is the code of the QMainWindow:
class A (QMainWindow):
def __init__(self):
QMainWindow.__init__(self)
#I create a QPushButton to open the QDialog
self.axes1 = self.figure_canvas.figure.add_axes ([0.8, 0.01, 0.19, 0.05])
self.button = QPushButton(self.axes1,"Open Dialog")
self.button.on_clicked(self.OpenDialog)
#This is the method to open the QDialog which is in another module
def OpenDialog(self, event):
text = configurePort.ConfigurePort.retrieve_data(self)
print text
What this code does is create a button in my QMainWindow and when I click it, it opens a QDialog, which is created in another module. And this is the code of the QDialog:
class ConfigurePort(QDialog):
def __init__(self, parent = None):
QDialog.__init__(self, parent)
uic.loadUi("configurePort.ui", self)
#I create a button to check active ports and show them
self.connect(self.btn_checkconn, SIGNAL("clicked()"), self.check_ports)
#This method calls another class which opens another QDialog
#and I select the port that I want
def check_ports(self):
self.check_serial = CheckPorts(self)
self.check_serial.exec_()
#After selecting the port, when I close the QDialog of the class named above
#the port´s name appears in the first QDialog
#classmethod
def retrieve_data(cls, parent = None):
dlg = cls(parent)
dlg.exec_()
text = dlg.getPortText()
return text
def closeEvent(self, event):
#Here is where I need to write the code to close the QDialog
#and it does not has to be an event
In the method, closeEvent, I need to write the necessary code, so I can close the window, and using the same button that I use to open it, open it again with the last information that it showed when I closed it.
I have tried to use QSettings but it did not worked (maybe I used it wrong). And I tried the show() and hide() classes of PyQt too, but it did not work. Hope you can help me.
----- EDIT -----
I edited the code of above. and I added some methods for a better understanding. So, i open the QDialog called ConfigurePort and it shows this:
The red circle, surrounds the port´s name. It is shown in a QLabel,and I take this text from the QDialog and then print it when I close the QDialog. I acomplish this thanks to a question I asked before, wich is in this link:
Getting data from child using PyQt
The check_port method shown in the code above, opens another QDialog that works great. With this I can select the ports that I need in my pc. So, this does not matter.
So, after closing the QDialog(and selecting for example "COM3", as you can see in the picture), I need to open it again, and see the same information that was shown before I closed it.
I tried to add this lines, using QSettings :
self.settings = QSettings("MyCompany", "MyApp")
if not self.settings.value("windowsState") == None:
self.restoreState(self.settings.value("windowState"))
But as I said before, I think that I did not use it right, but I hope that I solve this using something simpler.
----- EDIT 2 -----
Thank to the help of #Brendan Abel I have this code:
class ConfigurePort(QDialog):
def __init__(self, parent):
super(ConfigurePort, self).__init__(parent)
uic.loadUi("configurePort.ui", self)
self.myValue = 10
self.restoreSettings()
self.connect(self.btn_checkconn, SIGNAL("clicked()"), self.check_ports)
self.buttonBox.button(QDialogButtonBox.Cancel).clicked.connect(self.close)
self.buttonBox.button(QDialogButtonBox.Ok).clicked.connect(self.closeEvent)
self.iniUi()
def check_ports(self):
pass
def iniUi(self):
pass #I just create some QLabels in here
#classmethod
def retrieve_data(cls, parent = None):
dlg = cls(parent)
dlg.exec_()
text = dlg.getPortText()
return text
def closeEvent(self, event):
self.saveSettings()
super(QDialog,self).closeEvent(event)
def saveSettings(self):
settings = QSettings("MyOrg", "MyApp")
settings.setValue("myValue", self.myValue)
def restoreSettings(self):
settings = QSettings("MyOrg", "MyApp")
self.myValue = settings.value("myValue", self.myValue)
This gives me this error: TypeError: QWidget.closeEvent(QCloseEvent): argument 1 has unexpected type 'bool'
I know that I am missing something, but I can not see it.

There are a couple ways you could persist this data Generally, to persist data across sessions, you use QSettings and load the data in the __init__ and save it in the closeEvent method
Generally it looks something like this. This also assumes your using the v2 version of the QVariant api; otherwise, the results returned from QSettings.value is going to be a QVariant and you'll need to cast it to the appropriate python type. If you're using a recent version of PyQt then you should be on v2, but if not you can force it by sticking this at the top of your file
import sip
sip.setapi('QVariant', 2)
sip.setapi('QString', 2)
class MyDialog(QDialog):
def __init__(self, parent):
super(MyDialog, self).__init__(parent)
self.myvalue = 10
self.restoreSettings()
def closeEvent(self, event):
self.saveSettings()
super(MyDialog, self).closeEvent(event)
def saveSettings(self):
settings = QSettings('myorg', 'myapp')
settings.setValue('myvalue', self.myvalue)
def restoreSettings(self):
settings = QSettings('myorg', 'myapp')
self.myvalue = settings.value('myvalue', self.myvalue)
EDIT:
The error in your code is caused by this:
self.buttonBox.button(QDialogButtonBox.Ok).clicked.connect(self.closeEvent)
You shouldn't be calling or connecting to closeEvent directly. Instead, you should connect to .close or .accept
self.buttonBox.button(QDialogButtonBox.Ok).clicked.connect(self.accept)

You need to instantiate the ConfigurePort class then the self.configurePortDialog object should keep consistent. You will need to make sure if you have the user enter data that a cancel does not store the data and that an "ok" stores the data, but I not sure what you are putting in your dialog.
class A (QMainWindow):
def __init__(self):
QMainWindow.__init__(self)
#I create a QPushButton to open the QDialog
self.button = QPushButton("Open Dialog")
self.button.on_clicked(self.OpenDialog)
self.configurePortDialog = configurePort.ConfigurePort(parent=self)
self.configurePortDialog.accepted.connect(self.get_data)
#This is the method to open the QDialog which is in another module
def OpenDialog(self, event):
self.configurePortDialog.show()
#QtCore.Slot()
def get_data(self)
text = self.configurePortDialog.retrieve_data()
print text

refresh(update) widget in Nuke (vfx soft)

I need refresh(update) GUI widget(pySide) in Nuke(compositing software) after load or save nuke script.
callback: nuke.addOnScriptSave() and nuke.addOnScriptLoad()
import nuke
from PySide import QtGui, QtCore
from nukescripts import panels
class Info(QtGui.QWidget):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.initUI()
def scriptName(self):
sName = (nuke.root().name()).split('/')#split name from root
return sName
def initUI(self):
self.lbl1 = QtGui.QLabel("script name : " , self)
layout = QtGui.QHBoxLayout()#main layout
layout.addWidget(self.lbl1)
self.setLayout(layout)
self.updateInfo()
def updateInfo(self):
scriptName = self.scriptName()
self.lbl1.setText("script name : " + scriptName[-1].split('.')[0])#set name
panels.registerWidgetAsPanel('Info', 'Info_script', 'infoscript')

The simple solution is to add the callback registration to your widget's __init__:
class Info(QtGui.QWidget):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.initUI()
nuke.addOnScriptSave(self.updateInfo)
if nuke.root().name() == 'Root' and not nuke.modified():
# No reason to add a scriptLoad callback if opening a
# script would spawn a new Nuke process.
nuke.addOnScriptLoad(self.updateInfo)
# Rest of the class definition omitted for brevity
This approach does have a notable downside: Because Nuke's callback registry will now contain at least one reference to the widget's updateInfo method, the widget can never be garbage-collected by Python. This will probably never be too big of a deal in real life, since you will probably only ever create a very small number of panel instances, but if you ever created, say, 1000 instances, you would have 1000 callbacks registered that would never be unregistered (even if the panels were closed).
Unfortunately, Nuke doesn't really give you any hooks to implement when your widget is being removed from the UI, so it's tough to have a sure-fire way of knowing it's time to unregister your callbacks. The closest you can get is probably using a showEvent/hideEvent combo and some guesswork, like so:
class Info(QtGui.QWidget):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.initUI()
self.callbacksRegistered = False
def addCallbacks(self):
nuke.addOnScriptSave(self.updateInfo)
if nuke.root().name() == 'Root' and not nuke.modified():
# No reason to add a scriptLoad callback if opening a
# script would spawn a new Nuke process.
nuke.addOnScriptLoad(self.updateInfo)
def removeCallbacks(self):
self.removeOnScriptSave(self.updateInfo)
self.removeOnScriptLoad(self.updateInfo)
def showEvent(self, event):
if not (self.callbacksRegistered or event.spontaneous()):
self.addCallbacks()
self.callbacksRegistered = True
def hideEvent(self, event):
if self.callbacksRegistered and not event.spontaneous():
# "Spontaneous" hide events are sent when the Nuke
# window is minimized, which we don't really care
# about.
self.removeCallbacks()
self.callbacksRegistered = False
# Rest of the class definition omitted for brevity
The callback registration is moved into the showEvent method, and the callbacks are unregistered when the widget is hidden by something other than an OS-level window operation. This is pretty reliable, except that your callbacks will also be unregistered when you change to another tab in the widget's pane (if it's docked). They will obviously be re-added when your tab is activated again though. This is a pretty minor penalty, but I still think it's worth pointing out that while this approach is pretty close to ideal, it isn't quite perfect.
Anyway, I'll leave it up to you to decide which of these two you like better, but I hope this helps.

Open a second window in PyQt

I'm trying to use pyqt to show a custom QDialog window when a button on a QMainWindow is clicked. I keep getting the following error:
$ python main.py
DEBUG: Launch edit window
Traceback (most recent call last):
File "/home/james/Dropbox/Database/qt/ui_med.py", line 23, in launchEditWindow
dialog = Ui_Dialog(c)
File "/home/james/Dropbox/Database/qt/ui_edit.py", line 15, in __init__
QtGui.QDialog.__init__(self)
TypeError: descriptor '__init__' requires a 'sip.simplewrapper' object but received a 'Ui_Dialog'
I've gone over several online tutorials, but most of them stop just short of showing how to use a non built-in dialog window. I generated the code for both the main window and the dialog using pyuic4. What I think should be the relevant code is below. What am I missing here?
class Ui_Dialog(object):
def __init__(self, dbConnection):
QtGui.QDialog.__init__(self)
global c
c = dbConnection
class Ui_MainWindow(object):
def __init__(self, dbConnection):
global c
c = dbConnection
def launchEditWindow(self):
print "DEBUG: Launch edit window"
dialog = QtGui.QDialog()
dialogui = Ui_Dialog(c)
dialogui = setupUi(dialog)
dialogui.show()
class StartQT4(QtGui.QMainWindow):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
conn = sqlite3.connect('meds.sqlite')
c = conn.cursor()
self.ui = Ui_MainWindow(c)
self.ui.setupUi(self)
def main():
app = QtGui.QApplication(sys.argv)
program = StartQT4()
program.show()
sys.exit(app.exec_())
if __name__ == '__main__':
main()
Bonus question: since it looks like you can't pass arguments in pyqt function callbacks, is setting something which would otherwise be passed as an argument (the poorly named "c") to be global the best way to get information into those functions?

I've done like this in the past, and i can tell it works.
assuming your button is called "Button"
class Main(QtGui.QMainWindow):
''' some stuff '''
def on_Button_clicked(self, checked=None):
if checked==None: return
dialog = QDialog()
dialog.ui = Ui_MyDialog()
dialog.ui.setupUi(dialog)
dialog.setAttribute(QtCore.Qt.WA_DeleteOnClose)
dialog.exec_()
This works for my application, and I believe it should work with yours as well. hope it'll help, it should be pretty straight forward to do the few changes needed to apply it to your case.
have a good day everybody.

Ui_Dialog should inherent from QtGui.QDialog, not object.
class Ui_Dialog(QtGui.QDialog):
def __init__(self, dbConnection):
QtGui.QDialog.__init__(self)
global c
c = dbConnection

class StartQT4(QtGui.QMainWindow):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
Why QtGui.QWidget.__init___ ???
Use insted:
class StartQT4(QtGui.QMainWindow):
def __init__(self, parent=None):
QtGui.QMainWindow.__init__(self, parent)
You must call __init__ methon from base class (name in parenthesis '()')
QDialog have two useful routins:
exec_()
show()
First wait for closing dialog and then you can access any field form dialog. Second show dialog but don't wait, so to work properly you must set some slot/signals connections to respond for dialog actions.
eg. for exec_():
class Dialog(QDialog):
def __init__(self, parent):
QDialog.__init__(parent)
line_edit = QLineEdit()
...
dialog = Dialog()
if dialog.exec_(): # here dialog will be shown and main script will wait for its closing (with no errors)
data = dialog.line_edit.text()
Small tip: can you change your ui classes into widgets (with layouts). And perhaps problem is that your __init__ should be __init__(self, parent=None, dbConnection)
Because when you create new widget in existing one PyQt may try to set it as children of existing one. (So change all init to have additional parent param (must be on second position)).