[FIXED] Set selection from a list of indexes in a QTreeView

Issue

In PySide, is there a way to selected a few hundred treeview items without having to manually go row by row and select them? The problem with this method is the UI updates each time a new row is selected causing the application to freeze up while it finishes the method. Is there a way I can just pass the selection-model a list of all the rows I want selected?

My treeview has hundres of rows and four columns, but the treeview is set to select entire rows, not cells.

model = self.uiFilesList.model()
rows = self.selectedFileItems.selectedRows()
self.uiFilesList.selectionModel().clear()

I would expect this to work, but it doesn't.

selection = self.uiFilesList.selectionModel().selection()
self.uiFilesList.selectionModel().clear()
mode = QtGui.QItemSelectionModel.Select | QtGui.QItemSelectionModel.Rows
self.uiFilesList.selectionModel().select(selection, mode)

Here is my sample project where the selection is not updating after i update the data in the mode. You'll see in my sample below, when you right-click and change the age or the jersey number the list must be repopulated in order to update the displayed data. However i attempt to store the selection before updating the list. Then i try to restore it after the list is repopulated but it doesn't appear to work.

import sys, os, random
from PySide import QtGui, QtCore

class Person(object):

    def __init__(self, name, age, hair, jersey):
        self.name = name
        self.age = age
        self.hair = hair
        self.jersey = jersey


class MainWindow(QtGui.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.resize(500, 320)

        self.people = [
            Person('Kevin', 10, 'Brown', 20),
            Person('Marsha', 32, 'Blonde', 00),
            Person('Leslie', 27, 'Black', 15),
            Person('Tim', 53, 'Red', 37),
            Person('Marie', 65, 'Brown', 101),
            Person('Bella', 8, 'Blonde', 1)
        ]

        self.treeview = QtGui.QTreeView()
        self.treeview.setAlternatingRowColors(True)
        self.treeview.setModel(QtGui.QStandardItemModel())
        self.treeview.setSortingEnabled(True)
        self.treeview.setRootIsDecorated(False)
        self.treeview.setEditTriggers(QtGui.QAbstractItemView.NoEditTriggers)
        self.treeview.setSelectionBehavior(QtGui.QAbstractItemView.SelectRows)
        self.treeview.setSelectionMode(QtGui.QAbstractItemView.ExtendedSelection)
        self.treeview.setContextMenuPolicy(QtCore.Qt.CustomContextMenu)
        self.treeview.customContextMenuRequested.connect(self.open_menu)
        self.selectedItems = self.treeview.selectionModel()
        self.setCentralWidget(self.treeview)
        self.populate_list()

        # actions
        self.actRandomizeAges = QtGui.QAction('Randomize Ages', self)
        self.actRandomizeJerseys = QtGui.QAction('Randomize Jersey Numbers', self)

        # menu
        self.cmenu = QtGui.QMenu()
        self.cmenu.addAction(self.actRandomizeAges)
        self.cmenu.addAction(self.actRandomizeJerseys)

        # connections
        self.actRandomizeAges.triggered.connect(self.randomize_ages)
        self.actRandomizeJerseys.triggered.connect(self.randomize_jerseys)

    def open_menu(self, position):
        self.cmenu.exec_(self.treeview.viewport().mapToGlobal(position))


    def randomize_ages(self):
        rows = self.selectedItems.selectedRows()
        for i, item in enumerate(rows):
            obj = item.data(role=QtCore.Qt.UserRole)
            obj.age = random.randint(0, 70)
        self.populate_list()


    def randomize_jerseys(self):
        rows = self.selectedItems.selectedRows()
        for i, item in enumerate(rows):
            obj = item.data(role=QtCore.Qt.UserRole)
            obj.jersey = random.randint(1, 100)
        self.populate_list()


    def populate_list(self):
        selection = self.treeview.selectionModel().selection()
        flags = QtGui.QItemSelectionModel.Select
        self.treeview.selectionModel().clear()

        model = self.treeview.model()
        model.clear()
        model.setHorizontalHeaderLabels(['Name','Age','Hair', 'Jersey'])

        for p in self.people:
            # column 1
            col1 = QtGui.QStandardItem()
            col1.setData(p.name, role=QtCore.Qt.DisplayRole)
            col1.setData(p, role=QtCore.Qt.UserRole)
            # column 2
            col2 = QtGui.QStandardItem()
            col2.setData(p.age, role=QtCore.Qt.DisplayRole)
            if p.age > 30:
                col2.setData(QtGui.QBrush(QtGui.QColor(255,0,0,255)), role=QtCore.Qt.ForegroundRole)
            # column 3
            col3 = QtGui.QStandardItem()
            col3.setData(p.hair, role=QtCore.Qt.DisplayRole)
            # column 4
            col4 = QtGui.QStandardItem()
            col4.setData(p.jersey, role=QtCore.Qt.DisplayRole)
            if p.jersey > 30:
                col4.setData(QtGui.QBrush(QtGui.QColor(0,0,255,255)), role=QtCore.Qt.ForegroundRole)

            model.appendRow([col1, col2, col3, col4])

        self.treeview.selectionModel().select(selection, flags)

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

Solution

Your example doesn't work because it uses the wrong selection-flags. If you use QItemSelectionModel.Select alone, it will work correctly (and will select whole rows).

To set the selection from a list of indexes, you can create a series of QItemSelection objects which cover contiguous ranges, and merge them all into one selection.

Here is a demo script which shows how to do that:

import sys
from PySide import QtCore, QtGui

class Window(QtGui.QWidget):
    def __init__(self):
        super(Window, self).__init__()
        self.button = QtGui.QPushButton('Select')
        self.button.clicked.connect(self.handleButton)
        self.tree = QtGui.QTreeView()
        layout = QtGui.QVBoxLayout(self)
        layout.addWidget(self.tree)
        layout.addWidget(self.button)
        columns = 'One Two Three Four'.split()
        mod = QtGui.QStandardItemModel(self)
        mod.setHorizontalHeaderLabels(columns)
        for row in range(1000):
            mod.appendRow((
                QtGui.QStandardItem('A%s' % row),
                QtGui.QStandardItem('B%s' % row),
                QtGui.QStandardItem('C%s' % row),
                QtGui.QStandardItem('D%s' % row),
                ))
        self.tree.setModel(mod)
        self.tree.setSelectionMode(
            QtGui.QAbstractItemView.ExtendedSelection)

    def handleButton(self):
        mod = self.tree.model()
        columns = mod.columnCount() - 1
        flags = QtGui.QItemSelectionModel.Select
        selection = QtGui.QItemSelection()
        for start, end in ((2, 15), (25, 260), (500, 996)):
            start, end = mod.index(start, 0), mod.index(end, columns)
            if selection.indexes():
                selection.merge(QtGui.QItemSelection(start, end), flags)
            else:
                selection.select(start, end)
        self.tree.selectionModel().clear()
        self.tree.selectionModel().select(selection, flags)

if __name__ == '__main__':

    app = QtGui.QApplication(sys.argv)
    window = Window()
    window.setGeometry(700, 50, 500, 600)
    window.show()
    sys.exit(app.exec_())

UPDATE:

The example in your question doesn't work because your populate_list method clears the model, which will invalidate all the indexes in the selection. So you need a method to save the current selection as a list of row-numbers (rather than model-indexes). This can then be fed to the method I gave above to re-create the selection.

If you update your example as follows, it should work as expected:

def save_selection(self):
    selection = self.treeview.selectionModel().selectedRows()
    blocks = []
    for count, index in enumerate(sorted(selection)):
        row = index.row()
        if count > 0 and row == block[1] + 1:
            block[1] = row
        else:
            block = [row, row]
            blocks.append(block)
    return blocks

def create_selection(self, blocks):
    mod = self.treeview.model()
    columns = mod.columnCount() - 1
    flags = QtGui.QItemSelectionModel.Select
    selection = QtGui.QItemSelection()
    for start, end in blocks:
        start, end = mod.index(start, 0), mod.index(end, columns)
        if selection.indexes():
            selection.merge(QtGui.QItemSelection(start, end), flags)
        else:
            selection.select(start, end)
    self.treeview.selectionModel().clear()
    self.treeview.selectionModel().select(selection, flags)

def populate_list(self):
    selection = self.save_selection()

    ... # re-populate model

    self.create_selection(selection)

Answered By - ekhumoro