pyqt/model-views/todo_1.py

import os
import sys
import json

from PyQt5.QtCore import QAbstractListModel, Qt
from PyQt5.QtGui import QImage
from PyQt5.QtWidgets import QApplication, QMainWindow

from MainWindow import Ui_MainWindow

basedir = os.path.dirname(__file__)

flag = QImage(os.path.join(basedir, 'flag.png'))


class TodoModel(QAbstractListModel):

    def __init__(self, todos=None):
        super().__init__()
        self.todos = todos or []

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

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


class MainWindow(QMainWindow, Ui_MainWindow):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.setupUi(self)
        self.model = TodoModel()
        self.load()
        self.todoView.setModel(self.model)

        # Connect the button
        self.addButton.pressed.connect(self.add)
        self.deleteButton.pressed.connect(self.delete)
        self.completeButton.pressed.connect(self.complete)

    def load(self):
        try:
            with open("data.json", "r") as f:
                self.model.todos = json.load(f)
        except Exception as e:
            print(e)

    def save(self):
        with open("data.json", "w") as f:
            json.dump(self.model.todos, f)

    def add(self):
        """
        Add an item to our todos list, getting the QLineEdit.todoEdit
        and then clearing it
        :return:
        """
        text = self.todoEdit.text()
        text = text.strip()  # Remove whitespace
        if text:  # Don't add empty strings
            self.model.todos.append((False, text))
            # Trigger refresh
            self.model.layoutChanged.emit()
            # Empty the input
            self.todoEdit.setText("")
            self.save()

    def delete(self):
        """
        Delete the currently selected item from our model
        :return:
        """
        indexes = self.todoView.selectedIndexes()
        if indexes:
            index = indexes[0]
            # Remove the item and refresh
            del self.model.todos[index.row()]
            self.model.layoutChanged.emit()
            # Clear the selection (as it is no longer valid).
            self.todoView.clearSelection()
            self.save()

    def complete(self):
        """
        Mark the currently selected item as completed
        :return:
        """
        indexes = self.todoView.selectedIndexes()
        if indexes:
            index = indexes[0]
            row = index.row()
            status, text = self.model.todos[row]
            self.model.todos[row] = (True, text)
            # Emit dataChanged to update the view
            self.model.dataChanged.emit(index, index)
            # Clear the selection
            self.todoView.clearSelection()
            self.save()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = MainWindow()
    window.show()
    sys.exit(app.exec_())