Show a Loading Home Dialog before starting MainWindow

hachbani

Hi,

I have an app that parses a file and show data in QtableView. Before, I had a button in the mainwindow to load the source file. What I'm trying to implement now is a Dialog Window with only one button, the only purpose of this dialog window is to give a minimalistic and simple view to the user, where he can first select the file to be parsed and have a Loading progress bar (or something else) while the LoadData() function is runned. The Home Dialog should only be hidden/closed when the parsing is done.

What I'm achieving now:

The Home dialog starts
the user selects the file
the Home dialog disappears
LoadData is running
when LoadData is finished, the MainWindow shows with the data being parsed and tables filled.

Which is very close to what I want, except the part when the Home Dialog disappears before LoadData gets executed.

Here's my code if anyone can help.

class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self, parent=None):
        """
        ..
        __init__ code lines
        """
        self.hide()
        d = HomeDialog()
        if d.exec_():
            self.LoadData(d.path)

    def LoadData(self, file_path):
        """
        Parsing lines of code
        """

        #Parsing finished -> show the mainWindow
        self.show()

class HomeDialog(QtWidgets.QDialog, home_dialog.Ui_Dialog):
    def __init__(self, parent=None):
        super(HomeDialog, self).__init__(parent)
        self.setupUi(self)
        self.openB6.clicked.connect(self.get_file_name)

    def get_file_name(self):
        file_name = QtWidgets.QFileDialog.getOpenFileName(self, 'Open config file',
                                                            dir=path.join("/"),
                                                            filter="B6 (*.b6)")
        if not file_name[0]:
            return None
        else:
            self.path = file_name
            self.accept()

if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    app.setStyle(ProxyStyle())
    mainWin = MainWindow()
    mainWin.show()
    sys.exit(app.exec_())

SGaist

Hi,

It looks a bit like a "mini-wizard" so you could use a QWizard for that.

Not that if you have a long running operation, you might want to use QtConcurrent::run to execute it and let the GUI show a QProgressBar or a QProgressDialog depending on the road you take.

hachbani

Hi @SGaist ,

I've been looking at QWizard, not sure if this is what i'm looking for, in addition to that, I gave it a try but struggling hard to implement it. Is there now other classes I can use ?

JonB

@hachbani
Look at the QProgressBar/QProgressDialog alternative approach @SGaist suggested. That is the usual way to show the user when a background operation is running.

hachbani

@JonB

i've looking into QProgressDialog, the progressDialog is shown but not updated. From what I saw on several forums posts: do I have to use a QThread as well ?

Here's my code:

class progressBar(QtWidgets.QProgressDialog):
    def __init__(self, parent= None):
        super(progressBar, self).__init__(parent)
        pd = QtWidgets.QProgressDialog('loading...', 'cancel', 0, 100, self)

class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self, parent=None):
        """
        ..
        __init__ code lines
        """
        self.hide()
        d = HomeDialog()
        if d.exec_():
            self.LoadData(d.path)

    def LoadData(self, file_path):
        progress = progressBar()
        progress.show()
        progress.setValue(1)
        """
        Parsing lines of code
        progress.setValue(30)
        ..
        ..
        progress.setValue(70)
        ..
        ..
        """
        progress.hide()
        #Parsing finished -> show the mainWindow
        self.show()

class HomeDialog(QtWidgets.QDialog, home_dialog.Ui_Dialog):
    def __init__(self, parent=None):
        super(HomeDialog, self).__init__(parent)
        self.setupUi(self)
        self.openB6.clicked.connect(self.get_file_name)

    def get_file_name(self):
        file_name = QtWidgets.QFileDialog.getOpenFileName(self, 'Open config file',
                                                            dir=path.join("/"),
                                                            filter="B6 (*.b6)")
        if not file_name[0]:
            return None
        else:
            self.path = file_name
            self.accept()

if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    app.setStyle(ProxyStyle())
    mainWin = MainWindow()
    mainWin.show()
    sys.exit(app.exec_())

jsulm

@hachbani said in Show a Loading Home Dialog before starting MainWindow:

class progressBar(QtWidgets.QProgressDialog):
def init(self, parent= None):
super(progressBar, self).init(parent)
pd = QtWidgets.QProgressDialog('loading...', 'cancel', 0, 100, self)

Why do you create an instance of QtWidgets.QProgressDialog in progressBar which is already itself a QtWidgets.QProgressDialog?!

"do I have to use a QThread as well ?" - depends on how you process.

hachbani

To be honest I don't really know, for aesthetic reasons I guess, I've tried without creating the class (pd=QtWidgets.QProgressDialog('loading...', 'cancel', 0, 100, self) ) in the LoadData function. I get the same result

jsulm

@hachbani said in Show a Loading Home Dialog before starting MainWindow:

for aesthetic reasons I guess

Aesthetic reasons? There is absolutely no need for this pd - you are basically creating TWO progress dialogs (but only show one).
Why it does not work: well, you do not show how you process the data after showing progress dialog...

jsulm

@hachbani Basic approach is: show progress dialog, start your long lasting operation, on each iteration emit a signal which is connected to https://doc.qt.io/qt-5/qprogressdialog.html#value-prop slot.

hachbani

I updated the code a follow:

created a signal: self.change_val = QtCore.Signal(int) and connected it to a slot set_progress_val

in the LoadData, I emit change_val signal at different places.

Also did some changes in the if name == 'main'


class MainWindow(QtWidgets.QMainWindow,  Ui_MainWindow):

    change_val = QtCore.Signal(int)
    def __init__(self, file_name,parent=None):
        """
        super(MainWindow, self).__init__(parent)
        ..
        __init__ code lines
        """

        change_val.connect(self.set_progress_val)
        self.progress = QtWidgets.QProgressDialog('loading...', 'cancel', 0, 100, self)
        self.progress.show()
        self.LoadData(d.path)
    
    @QtCore.Slot(int)
    def set_progress_val(self, val):
        self.progress.setValue(val)

    def LoadData(self, file_path):
        
        """
        Parsing lines of code
        ..
        change_val.emit(30)
        ..
        ..
        change_val.emit(60)
        ..
        ..
        """
        self.progress.hide()
        #Parsing finished -> show the mainWindow
        self.show()

class HomeDialog(QtWidgets.QDialog, home_dialog.Ui_Dialog):
    def __init__(self, parent=None):
        super(HomeDialog, self).__init__(parent)
        self.setupUi(self)
        self.openB6.clicked.connect(self.get_file_name)

    def get_file_name(self):
        file_name = QtWidgets.QFileDialog.getOpenFileName(self, 'Open config file',
                                                            dir=path.join("/"),
                                                            filter="B6 (*.b6)")
        if not file_name[0]:
            return None
        else:
            self.path = file_name
            self.accept()

if __name__ == '__main__':
    app = QtWidgets.QApplication(sys.argv)
    app.setStyle(ProxyStyle())
    d = HomeDialog()
    if d.exec_():
        mainWin = MainWindow(file_name=d.path)
        mainWin.show()
        sys.exit(app.exec_())

I get the following error: 'str' object has no attribute 'connect'

JonB

@hachbani
On which line? self.change_val[int].connect(self.set_progress_val)? Are you using PyQt5, PySide2, or what?

hachbani

I'm using Pyside2, pyothn 3.8

I get the error on the follwoing line mainWin = MainWindow(file_name=d.path)

hachbani

The idea of self.change_val[int].connect(self.set_progress_val) is that when i'm going to call self.change_val.emit(20), the set_progress_val is called with 20 as argument, maybe I'm implementing this wrong

JonB

@hachbani
I'll look into the possible connect() issue in a moment. But

I get the error on the follwoing line mainWin = MainWindow(file_name=d.path)

mainWin = MainWindow(file_name=d.path)

I don't see your MainWindow.init() has a file_name argument?

Actually, before I look, could we establish where exactly this error is really coming from? With print() statements/debugger, do you actually get to the self.change_val[int].connect(self.set_progress_val) line at all? Or is the error really that constructor line??

hachbani

Just a pasting mistake, I updated the code in my last comment.

if I remove all the progressBar code parts, the program will run successfully, but with nothing being shown while the LoadData function is runnung

JonB

@hachbani

class MainWindow(QtWidgets.QMainWindow, file_name, Ui_MainWindow):
    def __init__(self, parent=None):

How do you manage file_name in the class declaration? How do you not have it in the __init__()? I'm not going to guess if this is in fact not the code you have, that's what pasting is for....

hachbani

@JonB said in Show a Loading Home Dialog before starting MainWindow:

Actually, before I look, could we establish where exactly this error is really coming from? With print() statements/debugger, do you actually get to the self.change_val[int].connect(self.set_progress_val) line at all? Or is the error really that constructor line??

I added a print before and after the connect line, I get the first print and then the 'str' object has no attribute 'connect'

the file_name argument gets passed to LoadData at the end of MainWindow __init__()

JonB

@hachbani said in Show a Loading Home Dialog before starting MainWindow:

the file_name argument gets passed to LoadData at the end of MainWindow init()

class MainWindow(QtWidgets.QMainWindow, file_name, Ui_MainWindow):

I don't understand. It's not an "argument", is it? You have it in the list of classes from which MainWindow derives?? Unless your knowledge of Python is better than mine.

hachbani

Sorry sorry, feel ridiculous, it was a mistake, the file_name is indeed an argument to MainWindow init(). I corrected the code in the comment. It was in init in my code, just a rookie mistake while making the minimalistic code

JonB

@hachbani
Please understand, we have to get pasting/correct code right! When you've tried to help in this forum for as much as I have you never know what posters have actually got if it's not accurate, and I have wasted too much time over the years answering questions about user code which is not actually the code! :)

I'll think about your connect() now....