Python Forum

In Qt Designer, I created a form, on which I placed a QlistWidget to display the processing progress:

from PyQt5 import QtWidgets, uic
from Database import Manager
from MyLib import Events, GUI
import Forms, General

class Form(QtWidgets.QWidget):

    def __init__(self, parent: QtWidgets.QMainWindow):
        QtWidgets.QWidget.__init__(self)
        
        ClassForm, _ = uic.loadUiType(Forms.Directory + 'CreateDatabase.ui')    
        self.ui = ClassForm()
        self.ui.setupUi(self)
        self.parent = parent
        
        #name of form
        self.setWindowTitle('Form for creating database')
        self.widget = QtWidgets.QWidget(self)
         
        layoutV = QtWidgets.QVBoxLayout()
        layoutV.addWidget(self.ui.label)
        layoutV.addWidget(self.ui.ButtonCreateDatabase)
        layoutV.addWidget(self.ui.MessageList)
        
        self.widget.setLayout(layoutV)
        self.setLayout(layoutV)
           
        self.ui.ButtonCreateDatabase.clicked.connect(self.CreateDatabase)
  
    ...
        
    def event(self, current_event: Events.EventForMessageList) -> bool:
        if current_event.type() !=  General.type_event:
            return False
         
        current_object = self.ui.MessageList
        current_object.addItem(current_event.message)
        return True

1. The form is perfectly created.
2. During execution of my procedure, events arrive to form.
3. They are processed without errors, including line: current_object.addItem(current_event.message)

, but no new lines appear on dialog form, in QListWidget. It always remains completely empty.
Why?

I animate the interface with this code (executed after receiving the event):

q_app = QtWidgets.QApplication.instance()
q_app.processEvents();

Moreover, the processing is finished and the interface should be rendered without any additional actions, but the list field remains empty.

---

The funny thing is that the number of invisible items in the list is growing! This code returns an ever-increasing value:

quantity = self.ui.MessageList.count()

self.ui.MessageList.item(quantity-2).text()

returns the correct value! That is, the list actually stores valid data!

---

I found a bug!!!

It is necessary to change the shape a little bit in size and the elements begin to appear :) But I "revive" the form with:

q_app = QtWidgets.QApplication.instance()
q_app.processEvents();

How to revive the form?

This is the correct code:

class MyThread(QtCore.QThread):
    def __init__(self, parent=None):
        QtCore.QThread.__init__(self, parent)
        
    def run(self):
        for i in range(1, 11):
            self.sleep(1)
            
            # Передача данных из потока через событие
            Events.message_error(str(i) + " Hop, Hey! La-la-ley!")

class MyList(QtWidgets.QListWidget):
    def __init__(self, parent=None):
        QtWidgets.QListWidget.__init__(self, parent)

    def customEvent(self, current_event: Events.EventForMessageList):
        if current_event.type() != General.type_event:
            return False
        
        self.addItem(current_event.message)
                            
class Form(QtWidgets.QWidget):
    def __init__(self, parent):
        QtWidgets.QWidget.__init__(self)
         
        #name of form
        self.setWindowTitle('Form for creating database')
        
        self.label = QtWidgets.QLabel('Обработка создания базы данных')
        self.ButtonCreateDatabase = QtWidgets.QPushButton("Создать")
        self.MessageList = MyList()
          
        self.layoutV = QtWidgets.QVBoxLayout()
        self.layoutV.addWidget(self.label)
        self.layoutV.addWidget(self.ButtonCreateDatabase)
        self.layoutV.addWidget(self.MessageList)
          
        self.setLayout(self.layoutV)
            
        self.thread = MyThread()
        
        self.ButtonCreateDatabase.clicked.connect(self.on_clicked)

    def on_clicked(self):
        General.generate_type_event()
        General.event_receiver = self.MessageList
        
        self.thread.start()