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Show a Loading Home Dialog before starting MainWindow

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  • H 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'

    JonBJ Offline
    JonBJ Offline
    JonB
    wrote on last edited by
    #11

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

    H 1 Reply Last reply
    0
    • JonBJ JonB

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

      H Offline
      H Offline
      hachbani
      wrote on last edited by
      #12

      I'm using Pyside2, pyothn 3.8

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

      JonBJ 1 Reply Last reply
      0
      • H Offline
        H Offline
        hachbani
        wrote on last edited by
        #13

        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

        1 Reply Last reply
        0
        • H hachbani

          I'm using Pyside2, pyothn 3.8

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

          JonBJ Offline
          JonBJ Offline
          JonB
          wrote on last edited by JonB
          #14

          @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??

          1 Reply Last reply
          0
          • H Offline
            H Offline
            hachbani
            wrote on last edited by hachbani
            #15

            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

            JonBJ 1 Reply Last reply
            0
            • H 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

              JonBJ Offline
              JonBJ Offline
              JonB
              wrote on last edited by JonB
              #16

              @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....

              1 Reply Last reply
              0
              • H Offline
                H Offline
                hachbani
                wrote on last edited by hachbani
                #17

                @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__()

                JonBJ 1 Reply Last reply
                0
                • H 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__()

                  JonBJ Offline
                  JonBJ Offline
                  JonB
                  wrote on last edited by JonB
                  #18

                  @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.

                  H 1 Reply Last reply
                  0
                  • JonBJ 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.

                    H Offline
                    H Offline
                    hachbani
                    wrote on last edited by hachbani
                    #19

                    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

                    JonBJ 1 Reply Last reply
                    0
                    • H 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

                      JonBJ Offline
                      JonBJ Offline
                      JonB
                      wrote on last edited by
                      #20

                      @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....

                      H 1 Reply Last reply
                      0
                      • JonBJ 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....

                        H Offline
                        H Offline
                        hachbani
                        wrote on last edited by
                        #21

                        Sorry again, I acknowledge that I've been wasting your time for a stupid mistake I've made pasting the code due to a lack of attention.

                        JonBJ 1 Reply Last reply
                        0
                        • H hachbani

                          Sorry again, I acknowledge that I've been wasting your time for a stupid mistake I've made pasting the code due to a lack of attention.

                          JonBJ Offline
                          JonBJ Offline
                          JonB
                          wrote on last edited by
                          #22

                          @hachbani
                          That's OK. At least you were polite enough to apologize, which is more than some :)

                          You may know PyQt5 more than me. But two things come to mind about your signal declaration

                          self.change_val = QtCore.Signal(int)
                          
                          • PyQt5 signals should be class members, not instance members?
                          • You should be using pyqtSignal(int), not QtCore.Signal(int)?
                          • Similarly, @pyqtSlot decorator instead of @QtCore.Slot(int)? Don't know if that matters.
                          class MainWindow(QtWidgets.QMainWindow,  Ui_MainWindow):
                              change_val = pyqtSignal(int)
                          

                          Do either of those improve? Reference https://doc.bccnsoft.com/docs/PyQt5/signals_slots.html

                          1 Reply Last reply
                          0
                          • H Offline
                            H Offline
                            hachbani
                            wrote on last edited by
                            #23

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

                            I'm using Pyside2, pyothn 3.8

                            I'm using Pyside2, I'll think more about your first point
                            PyQt5 signals should be class members, not instance members?

                            JonBJ 1 Reply Last reply
                            0
                            • H hachbani

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

                              I'm using Pyside2, pyothn 3.8

                              I'm using Pyside2, I'll think more about your first point
                              PyQt5 signals should be class members, not instance members?

                              JonBJ Offline
                              JonBJ Offline
                              JonB
                              wrote on last edited by JonB
                              #24

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

                              I'm using Pyside2,

                              Damn, so you are, that changes everything! I got distracted because someone called, damn....

                              PyQt5 signals should be class members, not instance members?

                              Yes, and I think this applies to PySide2 too, and is the cause of your error message. See 'PySide.QtCore.Signal' object has no attribute 'connect'?

                              And/or further, does your MainWindow.__init__() call super().__init__()? Omitting that can apparently lead to that error message too.

                              Finally, since your own signal does not seem to have multiple overloads, you could try plain

                              change_val.connect(self.set_progress_val)
                              

                              without that [int].

                              See also https://wiki.qt.io/Qt_for_Python_Signals_and_Slots

                              1 Reply Last reply
                              0
                              • H Offline
                                H Offline
                                hachbani
                                wrote on last edited by
                                #25

                                I've declared change_val as a class member, I get an error name 'change_val' is not defined

                                I've updated the code in my last comment. I do indeed call super in MainWindow init()

                                JonBJ 1 Reply Last reply
                                0
                                • H hachbani

                                  I've declared change_val as a class member, I get an error name 'change_val' is not defined

                                  I've updated the code in my last comment. I do indeed call super in MainWindow init()

                                  JonBJ Offline
                                  JonBJ Offline
                                  JonB
                                  wrote on last edited by
                                  #26

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

                                  've declared change_val as a class member, I get an error name 'change_val' is not defined

                                  Refer the https://wiki.qt.io/Qt_for_Python_Signals_and_Slots I quoted earlier for examples. It may be that to reference the class variable you have to go self.change_val or MainWindow.change_val?

                                  1 Reply Last reply
                                  0
                                  • H Offline
                                    H Offline
                                    hachbani
                                    wrote on last edited by
                                    #27

                                    Thanjs @JonB for you help ! Indeed the self.change_val worked. I get my ProgressDialog, I added some prints in set_progress_val to debug if it's been called correctly, and it is. The problem is the progressDialog freezes, no progress is shown.

                                    Here's the actual code:

                                    
                                    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
                                            """
                                    
                                            self.change_val[int].connect(self.set_progress_val)
                                            self.progress = QtWidgets.QProgressDialog('loading...', 'cancel', 0, 100, self)
                                            self.progress.setValue(0)
                                            self.progress.show()
                                            self.LoadData(d.path)
                                        
                                        @QtCore.Slot(int)
                                        def set_progress_val(self, val):
                                            print('progress setVal called, new val: ', self.progress.value())
                                            self.progress.setValue(val)
                                    
                                        def LoadData(self, file_path):
                                            
                                            """
                                            Parsing lines of code
                                            ..
                                            self.change_val.emit(30)
                                            ..
                                            ..
                                            self.change_val.emit(60)
                                            ..
                                            ..
                                            """
                                            self.change_val.emit(100)
                                            #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_())
                                    

                                    Here's a screenshot of the displayed window when progressDialog is displayed:

                                    df738644-f964-4ead-bd2a-6c45d765e981-image.png

                                    JonBJ 1 Reply Last reply
                                    0
                                    • H hachbani

                                      Thanjs @JonB for you help ! Indeed the self.change_val worked. I get my ProgressDialog, I added some prints in set_progress_val to debug if it's been called correctly, and it is. The problem is the progressDialog freezes, no progress is shown.

                                      Here's the actual code:

                                      
                                      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
                                              """
                                      
                                              self.change_val[int].connect(self.set_progress_val)
                                              self.progress = QtWidgets.QProgressDialog('loading...', 'cancel', 0, 100, self)
                                              self.progress.setValue(0)
                                              self.progress.show()
                                              self.LoadData(d.path)
                                          
                                          @QtCore.Slot(int)
                                          def set_progress_val(self, val):
                                              print('progress setVal called, new val: ', self.progress.value())
                                              self.progress.setValue(val)
                                      
                                          def LoadData(self, file_path):
                                              
                                              """
                                              Parsing lines of code
                                              ..
                                              self.change_val.emit(30)
                                              ..
                                              ..
                                              self.change_val.emit(60)
                                              ..
                                              ..
                                              """
                                              self.change_val.emit(100)
                                              #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_())
                                      

                                      Here's a screenshot of the displayed window when progressDialog is displayed:

                                      df738644-f964-4ead-bd2a-6c45d765e981-image.png

                                      JonBJ Offline
                                      JonBJ Offline
                                      JonB
                                      wrote on last edited by
                                      #28

                                      @hachbani
                                      Because LoadData() is in your GUI thread, Qt does not get to redraw/refresh the UI while it is running. I assume your bar shows once as "full" right at the end? I haven't used QProgressBar, but I imagine you should play with one of the following:

                                      • Move LoadFile() to its own thread. That's the nicest, but can be the most code.

                                      • Try self.progress.repaint() in your slot.

                                      • Try QCoreApplication.processEvents() in your slot.

                                      Is set_progress_val() called against each emit()? I think it is, because you are using DirectConnection; if not you can always call set_progress_val() directly instead of going via a signal.

                                      1 Reply Last reply
                                      3
                                      • H Offline
                                        H Offline
                                        hachbani
                                        wrote on last edited by
                                        #29

                                        Hey, thanks so much man !!! I added QtCore.QCoreApplication.processEvents() to my slot, and it works !!

                                        Maybe I'm going to take a look really later on the first point, about moving LoadData() to another thread, it seems interesting (I just never worked with QThread)

                                        going to update the post with the full solution later, in case It'd save someone's day.

                                        Have a nice week

                                        JonBJ 1 Reply Last reply
                                        1
                                        • H hachbani

                                          Hey, thanks so much man !!! I added QtCore.QCoreApplication.processEvents() to my slot, and it works !!

                                          Maybe I'm going to take a look really later on the first point, about moving LoadData() to another thread, it seems interesting (I just never worked with QThread)

                                          going to update the post with the full solution later, in case It'd save someone's day.

                                          Have a nice week

                                          JonBJ Offline
                                          JonBJ Offline
                                          JonB
                                          wrote on last edited by
                                          #30

                                          @hachbani
                                          Threads are tempting, especially for beginners, but nasty to get right, and I think more of an issue in Python than C++.

                                          processEvents() is a bit "naughty", but awfully simple if it works. You probably have more important things to move onto than spending ages on a loading progress screen :)

                                          The only thing is: if your LoadData() takes a bit of time, try clicking on something on the main window which has a slot action while it is still loading the data. The problem is that slot will execute, and if it expects your data load to be complete it won't be.

                                          Have a look at the example at https://doc.qt.io/qt-5/qprogressdialog.html#details where

                                          Compared to a modeless QProgressDialog, a modal QProgressDialog is simpler to use for the programmer. Do the operation in a loop, call setValue() at intervals

                                          Is that code implying you can call QProgressDialog.setValue() as you go along without you having to worry about the event loop for updates? If that pattern works for you I'd be tempted to adopt it?

                                          1 Reply Last reply
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