Editable Tree Model Example#

A Python application that demonstrates the analogous example in C++ Editable Tree Model Example

editabletreemodel screenshot
import sys
from PySide6.QtWidgets import QApplication
from mainwindow import MainWindow


if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = MainWindow()
    window.show()
    sys.exit(app.exec())
import sys
from pathlib import Path

from PySide6.QtCore import (QAbstractItemModel, QItemSelectionModel,
                            QModelIndex, Qt, Slot)
from PySide6.QtWidgets import (QAbstractItemView, QMainWindow, QTreeView,
                               QWidget)
from PySide6.QtTest import QAbstractItemModelTester

from treemodel import TreeModel


class MainWindow(QMainWindow):
    def __init__(self, parent: QWidget = None):
        super().__init__(parent)
        self.resize(573, 468)

        self.view = QTreeView()
        self.view.setAlternatingRowColors(True)
        self.view.setSelectionBehavior(QAbstractItemView.SelectItems)
        self.view.setHorizontalScrollMode(QAbstractItemView.ScrollPerPixel)
        self.view.setAnimated(False)
        self.view.setAllColumnsShowFocus(True)
        self.setCentralWidget(self.view)

        menubar = self.menuBar()
        file_menu = menubar.addMenu("&File")
        self.exit_action = file_menu.addAction("E&xit")
        self.exit_action.setShortcut("Ctrl+Q")
        self.exit_action.triggered.connect(self.close)

        actions_menu = menubar.addMenu("&Actions")
        actions_menu.triggered.connect(self.update_actions)
        self.insert_row_action = actions_menu.addAction("Insert Row")
        self.insert_row_action.setShortcut("Ctrl+I, R")
        self.insert_row_action.triggered.connect(self.insert_row)
        self.insert_column_action = actions_menu.addAction("Insert Column")
        self.insert_column_action.setShortcut("Ctrl+I, C")
        self.insert_column_action.triggered.connect(self.insert_column)
        actions_menu.addSeparator()
        self.remove_row_action = actions_menu.addAction("Remove Row")
        self.remove_row_action.setShortcut("Ctrl+R, R")
        self.remove_row_action.triggered.connect(self.remove_row)
        self.remove_column_action = actions_menu.addAction("Remove Column")
        self.remove_column_action.setShortcut("Ctrl+R, C")
        self.remove_column_action.triggered.connect(self.remove_column)
        actions_menu.addSeparator()
        self.insert_child_action = actions_menu.addAction("Insert Child")
        self.insert_child_action.setShortcut("Ctrl+N")
        self.insert_child_action.triggered.connect(self.insert_child)
        help_menu = menubar.addMenu("&Help")
        about_qt_action = help_menu.addAction("About Qt", qApp.aboutQt)
        about_qt_action.setShortcut("F1")

        self.setWindowTitle("Editable Tree Model")

        headers = ["Title", "Description"]

        file = Path(__file__).parent / "default.txt"
        self.model = TreeModel(headers, file.read_text(), self)

        if "-t" in sys.argv:
            QAbstractItemModelTester(self.model, self)
        self.view.setModel(self.model)
        self.view.expandAll()

        for column in range(self.model.columnCount()):
            self.view.resizeColumnToContents(column)

        selection_model = self.view.selectionModel()
        selection_model.selectionChanged.connect(self.update_actions)

        self.update_actions()

    @Slot()
    def insert_child(self) -> None:
        selection_model = self.view.selectionModel()
        index: QModelIndex = selection_model.currentIndex()
        model: QAbstractItemModel = self.view.model()

        if model.columnCount(index) == 0:
            if not model.insertColumn(0, index):
                return

        if not model.insertRow(0, index):
            return

        for column in range(model.columnCount(index)):
            child: QModelIndex = model.index(0, column, index)
            model.setData(child, "[No data]", Qt.EditRole)
            if not model.headerData(column, Qt.Horizontal):
                model.setHeaderData(column, Qt.Horizontal, "[No header]",
                                    Qt.EditRole)

        selection_model.setCurrentIndex(
            model.index(0, 0, index), QItemSelectionModel.ClearAndSelect
        )
        self.update_actions()

    @Slot()
    def insert_column(self) -> None:
        model: QAbstractItemModel = self.view.model()
        column: int = self.view.selectionModel().currentIndex().column()

        changed: bool = model.insertColumn(column + 1)
        if changed:
            model.setHeaderData(column + 1, Qt.Horizontal, "[No header]",
                                Qt.EditRole)

        self.update_actions()

    @Slot()
    def insert_row(self) -> None:
        index: QModelIndex = self.view.selectionModel().currentIndex()
        model: QAbstractItemModel = self.view.model()
        parent: QModelIndex = index.parent()

        if not model.insertRow(index.row() + 1, parent):
            return

        self.update_actions()

        for column in range(model.columnCount(parent)):
            child: QModelIndex = model.index(index.row() + 1, column, parent)
            model.setData(child, "[No data]", Qt.EditRole)

    @Slot()
    def remove_column(self) -> None:
        model: QAbstractItemModel = self.view.model()
        column: int = self.view.selectionModel().currentIndex().column()

        if model.removeColumn(column):
            self.update_actions()

    @Slot()
    def remove_row(self) -> None:
        index: QModelIndex = self.view.selectionModel().currentIndex()
        model: QAbstractItemModel = self.view.model()

        if model.removeRow(index.row(), index.parent()):
            self.update_actions()

    @Slot()
    def update_actions(self) -> None:
        selection_model = self.view.selectionModel()
        has_selection: bool = not selection_model.selection().isEmpty()
        self.remove_row_action.setEnabled(has_selection)
        self.remove_column_action.setEnabled(has_selection)

        current_index = selection_model.currentIndex()
        has_current: bool = current_index.isValid()
        self.insert_row_action.setEnabled(has_current)
        self.insert_column_action.setEnabled(has_current)

        if has_current:
            self.view.closePersistentEditor(current_index)
            msg = f"Position: ({current_index.row()},{current_index.column()})"
            if not current_index.parent().isValid():
                msg += " in top level"
            self.statusBar().showMessage(msg)
class TreeItem:
    def __init__(self, data: list, parent: 'TreeItem' = None):
        self.item_data = data
        self.parent_item = parent
        self.child_items = []

    def child(self, number: int) -> 'TreeItem':
        if number < 0 or number >= len(self.child_items):
            return None
        return self.child_items[number]

    def last_child(self):
        return self.child_items[-1] if self.child_items else None

    def child_count(self) -> int:
        return len(self.child_items)

    def child_number(self) -> int:
        if self.parent_item:
            return self.parent_item.child_items.index(self)
        return 0

    def column_count(self) -> int:
        return len(self.item_data)

    def data(self, column: int):
        if column < 0 or column >= len(self.item_data):
            return None
        return self.item_data[column]

    def insert_children(self, position: int, count: int, columns: int) -> bool:
        if position < 0 or position > len(self.child_items):
            return False

        for row in range(count):
            data = [None] * columns
            item = TreeItem(data.copy(), self)
            self.child_items.insert(position, item)

        return True

    def insert_columns(self, position: int, columns: int) -> bool:
        if position < 0 or position > len(self.item_data):
            return False

        for column in range(columns):
            self.item_data.insert(position, None)

        for child in self.child_items:
            child.insert_columns(position, columns)

        return True

    def parent(self):
        return self.parent_item

    def remove_children(self, position: int, count: int) -> bool:
        if position < 0 or position + count > len(self.child_items):
            return False

        for row in range(count):
            self.child_items.pop(position)

        return True

    def remove_columns(self, position: int, columns: int) -> bool:
        if position < 0 or position + columns > len(self.item_data):
            return False

        for column in range(columns):
            self.item_data.pop(position)

        for child in self.child_items:
            child.remove_columns(position, columns)

        return True

    def set_data(self, column: int, value):
        if column < 0 or column >= len(self.item_data):
            return False

        self.item_data[column] = value
        return True

    def __repr__(self) -> str:
        result = f"<treeitem.TreeItem at 0x{id(self):x}"
        for d in self.item_data:
            result += f' "{d}"' if d else " <None>"
        result += f", {len(self.child_items)} children>"
        return result
from PySide6.QtCore import QModelIndex, Qt, QAbstractItemModel, Signal
from treeitem import TreeItem


class TreeModel(QAbstractItemModel):
    # Define signals
    dataChanged = Signal(QModelIndex, QModelIndex, object)
    headerDataChanged = Signal(Qt.Orientation, int, int)

    def __init__(self, headers: list, data: str, parent=None):
        super().__init__(parent)

        self.root_data = headers
        self.root_item = TreeItem(self.root_data.copy())
        self.setup_model_data(data.split("\n"), self.root_item)

    def columnCount(self, parent: QModelIndex = None) -> int:
        return self.root_item.column_count()

    def data(self, index: QModelIndex, role: int = None):
        if not index.isValid():
            return None

        if role != Qt.DisplayRole and role != Qt.EditRole:
            return None

        item: TreeItem = self.get_item(index)

        return item.data(index.column())

    def flags(self, index: QModelIndex) -> Qt.ItemFlags:
        if not index.isValid():
            return Qt.NoItemFlags

        return Qt.ItemIsEditable | QAbstractItemModel.flags(self, index)

    def get_item(self, index: QModelIndex = QModelIndex()) -> TreeItem:
        if index.isValid():
            item: TreeItem = index.internalPointer()
            if item:
                return item

        return self.root_item

    def headerData(self, section: int, orientation: Qt.Orientation,
                   role: int = Qt.DisplayRole):
        if orientation == Qt.Horizontal and role == Qt.DisplayRole:
            return self.root_item.data(section)

        return None

    def index(self, row: int, column: int, parent: QModelIndex = QModelIndex()) -> QModelIndex:
        if parent.isValid() and parent.column() != 0:
            return QModelIndex()

        parent_item: TreeItem = self.get_item(parent)
        if not parent_item:
            return QModelIndex()

        child_item: TreeItem = parent_item.child(row)
        if child_item:
            return self.createIndex(row, column, child_item)
        return QModelIndex()

    def insertColumns(self, position: int, columns: int,
                      parent: QModelIndex = QModelIndex()) -> bool:
        self.beginInsertColumns(parent, position, position + columns - 1)
        success: bool = self.root_item.insert_columns(position, columns)
        self.endInsertColumns()

        return success

    def insertRows(self, position: int, rows: int,
                   parent: QModelIndex = QModelIndex()) -> bool:
        parent_item: TreeItem = self.get_item(parent)
        if not parent_item:
            return False

        self.beginInsertRows(parent, position, position + rows - 1)
        column_count = self.root_item.column_count()
        success: bool = parent_item.insert_children(position, rows, column_count)
        self.endInsertRows()

        return success

    def parent(self, index: QModelIndex = QModelIndex()) -> QModelIndex:
        if not index.isValid():
            return QModelIndex()

        child_item: TreeItem = self.get_item(index)
        if child_item:
            parent_item: TreeItem = child_item.parent()
        else:
            parent_item = None

        if parent_item == self.root_item or not parent_item:
            return QModelIndex()

        return self.createIndex(parent_item.child_number(), 0, parent_item)

    def removeColumns(self, position: int, columns: int,
                      parent: QModelIndex = QModelIndex()) -> bool:
        self.beginRemoveColumns(parent, position, position + columns - 1)
        success: bool = self.root_item.remove_columns(position, columns)
        self.endRemoveColumns()

        if self.root_item.column_count() == 0:
            self.removeRows(0, self.rowCount())

        return success

    def removeRows(self, position: int, rows: int,
                   parent: QModelIndex = QModelIndex()) -> bool:
        parent_item: TreeItem = self.get_item(parent)
        if not parent_item:
            return False

        self.beginRemoveRows(parent, position, position + rows - 1)
        success: bool = parent_item.remove_children(position, rows)
        self.endRemoveRows()

        return success

    def rowCount(self, parent: QModelIndex = QModelIndex()) -> int:
        if parent.isValid() and parent.column() > 0:
            return 0

        parent_item: TreeItem = self.get_item(parent)
        if not parent_item:
            return 0
        return parent_item.child_count()

    def setData(self, index: QModelIndex, value, role: int) -> bool:
        if role != Qt.EditRole:
            return False

        item: TreeItem = self.get_item(index)
        result: bool = item.set_data(index.column(), value)

        if result:
            self.dataChanged.emit(index, index, [Qt.DisplayRole, Qt.EditRole])

        return result

    def setHeaderData(self, section: int, orientation: Qt.Orientation, value,
                      role: int = None) -> bool:
        if role != Qt.EditRole or orientation != Qt.Horizontal:
            return False

        result: bool = self.root_item.set_data(section, value)

        if result:
            # todo: Check if emit headerDataChanged signal is correct
            # emit headerDataChanged(orientation, section, section)
            self.headerDataChanged(orientation, section, section)

        return result

    def setup_model_data(self, lines: list, parent: TreeItem):
        parents = [parent]
        indentations = [0]

        for line in lines:
            line = line.rstrip()
            if line and "\t" in line:

                position = 0
                while position < len(line):
                    if line[position] != " ":
                        break
                    position += 1

                column_data = line[position:].split("\t")
                column_data = [string for string in column_data if string]

                if position > indentations[-1]:
                    if parents[-1].child_count() > 0:
                        parents.append(parents[-1].last_child())
                        indentations.append(position)
                else:
                    while position < indentations[-1] and parents:
                        parents.pop()
                        indentations.pop()

                parent: TreeItem = parents[-1]
                col_count = self.root_item.column_count()
                parent.insert_children(parent.child_count(), 1, col_count)

                for column in range(len(column_data)):
                    child = parent.last_child()
                    child.set_data(column, column_data[column])

    def _repr_recursion(self, item: TreeItem, indent: int = 0) -> str:
        result = " " * indent + repr(item) + "\n"
        for child in item.child_items:
            result += self._repr_recursion(child, indent + 2)
        return result

    def __repr__(self) -> str:
        return self._repr_recursion(self.root_item)
Getting Started                         How to familiarize yourself with Qt Designer
    Launching Designer                  Running the Qt Designer application
    The User Interface                  How to interact with Qt Designer

Designing a Component                   Creating a GUI for your application
    Creating a Dialog                   How to create a dialog
    Composing the Dialog                Putting widgets into the dialog example
    Creating a Layout                   Arranging widgets on a form
    Signal and Slot Connections         Making widget communicate with each other

Using a Component in Your Application   Generating code from forms
    The Direct Approach                 Using a form without any adjustments
    The Single Inheritance Approach     Subclassing a form's base class
    The Multiple Inheritance Approach   Subclassing the form itself
    Automatic Connections               Connecting widgets using a naming scheme
        A Dialog Without Auto-Connect   How to connect widgets without a naming scheme
        A Dialog With Auto-Connect      Using automatic connections

Form Editing Mode                       How to edit a form in Qt Designer
    Managing Forms                      Loading and saving forms
    Editing a Form                      Basic editing techniques
    The Property Editor                 Changing widget properties
    The Object Inspector                Examining the hierarchy of objects on a form
    Layouts                             Objects that arrange widgets on a form
        Applying and Breaking Layouts   Managing widgets in layouts
        Horizontal and Vertical Layouts Standard row and column layouts
        The Grid Layout                 Arranging widgets in a matrix
    Previewing Forms                    Checking that the design works

Using Containers                        How to group widgets together
    General Features                    Common container features
    Frames                              QFrame
    Group Boxes                         QGroupBox
    Stacked Widgets                     QStackedWidget
    Tab Widgets                         QTabWidget
    Toolbox Widgets                     QToolBox

Connection Editing Mode                 Connecting widgets together with signals and slots
    Connecting Objects                  Making connections in Qt Designer
    Editing Connections                 Changing existing connections