todo.py

import sys
from PyQt5 import QtCore, QtGui, QtWidgets, uic
from PyQt5.QtCore import Qt


qt_creator_file = "mainwindow.ui"
Ui_MainWindow, QtBaseClass = uic.loadUiType(qt_creator_file)


class TodoModel(QtCore.QAbstractListModel):
    def __init__(self, *args, todos=None, **kwargs):
        super(TodoModel, self).__init__(*args, **kwargs)
        self.todos = todos or []

    def data(self, index, role):
        if role == Qt.DisplayRole:
            status, text = self.todos[index.row()]
            return text

    def rowCount(self, index):
        return len(self.todos)


class MainWindow(QtWidgets.QMainWindow, Ui_MainWindow):
    def __init__(self):
        QtWidgets.QMainWindow.__init__(self)
        Ui_MainWindow.__init__(self)
        self.setupUi(self)
        self.model = TodoModel()
        self.todoView.setModel(self.model)


app = QtWidgets.QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec_()