Custom model development for QTreeView

[tilz0R]

I have a QTreeView and would like to develop custom model. In the final usage, I'm using SQLite to get table, and then with one-to-many relationship, to display its parameters at second level.

For first tests, I have 2 classes: MyItem and MyItemParam, that both provide data to display. First one also holds array of second one (one MyItem has many MyItemParam classes).

This is the direct example I made. I'm obviously struggling to get the correct data. I think main failure I have is around parent and index methods.

Is there a good example to build custom model? I simply do not like to use QStandardItemModel for each of the line. I'd rather provide data as one big source, and then use model, to construct necessary tree.

You can run the script directly. PySide 6.4.2 was used for the tests.

What I want:

import sys
from PySide6.QtWidgets import *
from PySide6.QtCore import *
from PySide6.QtUiTools import *

# Item object with name, title and parameters
class MyItem():
    def __init__(self, name, title):
        self.name = name
        self.title = title
        self.params = []

    def add_param(self, param):
        self.params.append(param)

# MyItemParam with key and value
class MyItemParam():
    def __init__(self, key, value):
        self.key = key
        self.value = value

# Treeview model
class TreeModel(QAbstractItemModel):
    def __init__(self):
        super().__init__()
        self._data = []

    # Columns and rows
    def columnCount(self, parent):  return 2
    def rowCount(self, parent):     
        if parent.isValid():
            item = parent.internalPointer()
            if isinstance(item, MyItem):
                return len(item.params)
            else:
                return 0
        return len(self._data)

    # Index creation
    def index(self, row, column, parent = QModelIndex()):
        if parent.isValid():
            item = parent.internalPointer()
            if isinstance(item, MyItem):
                item = item.params[row]
        else:
            item = self._data[row]
        return self.createIndex(row, column, item)

    # Parent object
    def parent(self, index):
        if not index.isValid():
            return QModelIndex()
        item = index.internalPointer()
        return self.createIndex(index.row(), index.column(), item)
        
    # Get data
    def data(self, index, role):
        item = index.internalPointer()
        if role == Qt.ItemDataRole.DisplayRole:
            column = index.column()
            # Print Item data
            if isinstance(item, MyItem):
                if column == 0:
                    return item.name
                elif column == 1:
                    return item.title
            # Print param data
            elif isinstance(item, MyItemParam):
                if column == 0:
                    return item.key
                elif column == 1:
                    return item.value
        return None

    # Add data to the model
    def load_custom_data(self, data):
        self.beginResetModel()
        self._data = data
        self.endResetModel()

# Main window
class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.resize(800, 480)

        # Set widgets
        treeview = QTreeView()
        treemodel = TreeModel()
        treeview.setModel(treemodel)

        # Build items
        item1 = MyItem("Item 1", "Item 1 title")
        item1.add_param(MyItemParam('key1', 'value1'))
        item1.add_param(MyItemParam('key2', 'value2'))
        item1.add_param(MyItemParam('key3', 'value3'))
        item2 = MyItem("Item 2", "Item 2 title")
        item2.add_param(MyItemParam('key4', 'value4'))
        item2.add_param(MyItemParam('key5', 'value5'))
        item2.add_param(MyItemParam('key6', 'value6'))
        item3 = MyItem("Item 3", "Item 3 title")
        item3.add_param(MyItemParam('key7', 'value7'))
        item3.add_param(MyItemParam('key8', 'value8'))
        item3.add_param(MyItemParam('key9', 'value9'))

        # Load data to the model
        treemodel.load_custom_data([item1, item2, item3])

        self.setCentralWidget(treeview)
        self.show()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    widget = MainWindow()
    sys.exit(app.exec())

[SGaist]

Hi,

The Simple Tree Model example should help you get started.

[tilz0R]

Let me emphasize that the issue is with actual tree. First level is well displayed.

[SGaist]

Hi,

The Simple Tree Model example should help you get started.