PyQt - Column of Checkboxes in a QTableView

Question

I am dynamically creating a QTableView from a Pandas dataframe. I have example code here.

I can create the table, with the checkboxes but I cannot get the checkboxes to reflect the model data, or even to change at all to being unchecked.

I am following example code from this previous question and taking @raorao answer as a guide. This will display the boxes in the table, but non of the functionality is working.

Can anyone suggest any changes, or what is wrong with this code. Why is it not reflecting the model, and why can it not change?

Do check out my full example code here.

Edit one : Update after comment from Frodon : corrected string cast to bool with a comparison xxx == 'True'

class CheckBoxDelegate(QtGui.QStyledItemDelegate):
    """
    A delegate that places a fully functioning QCheckBox in every
    cell of the column to which it's applied
    """
    def __init__(self, parent):
        QtGui.QItemDelegate.__init__(self, parent)

    def createEditor(self, parent, option, index):
        '''
        Important, otherwise an editor is created if the user clicks in this cell.
        ** Need to hook up a signal to the model
        '''
        return None

    def paint(self, painter, option, index):
        '''
        Paint a checkbox without the label.
        '''
        checked = index.model().data(index, QtCore.Qt.DisplayRole) == 'True'
        check_box_style_option = QtGui.QStyleOptionButton()

        if (index.flags() & QtCore.Qt.ItemIsEditable) > 0:
            check_box_style_option.state |= QtGui.QStyle.State_Enabled
        else:
            check_box_style_option.state |= QtGui.QStyle.State_ReadOnly

        if checked:
            check_box_style_option.state |= QtGui.QStyle.State_On
        else:
            check_box_style_option.state |= QtGui.QStyle.State_Off

        check_box_style_option.rect = self.getCheckBoxRect(option)

        # this will not run - hasFlag does not exist
        #if not index.model().hasFlag(index, QtCore.Qt.ItemIsEditable):
            #check_box_style_option.state |= QtGui.QStyle.State_ReadOnly

        check_box_style_option.state |= QtGui.QStyle.State_Enabled

        QtGui.QApplication.style().drawControl(QtGui.QStyle.CE_CheckBox, check_box_style_option, painter)

    def editorEvent(self, event, model, option, index):
        '''
        Change the data in the model and the state of the checkbox
        if the user presses the left mousebutton or presses
        Key_Space or Key_Select and this cell is editable. Otherwise do nothing.
        '''
        print 'Check Box editor Event detected : ' 
        if not (index.flags() & QtCore.Qt.ItemIsEditable) > 0:
            return False

        print 'Check Box edior Event detected : passed first check' 
        # Do not change the checkbox-state
        if event.type() == QtCore.QEvent.MouseButtonRelease or event.type() == QtCore.QEvent.MouseButtonDblClick:
            if event.button() != QtCore.Qt.LeftButton or not self.getCheckBoxRect(option).contains(event.pos()):
                return False
            if event.type() == QtCore.QEvent.MouseButtonDblClick:
                return True
        elif event.type() == QtCore.QEvent.KeyPress:
            if event.key() != QtCore.Qt.Key_Space and event.key() != QtCore.Qt.Key_Select:
                return False
            else:
                return False

        # Change the checkbox-state
        self.setModelData(None, model, index)
        return True

Is this line: `checked = bool(index.model().data(index, QtCore.Qt.DisplayRole))` really gives a boolean ? I would have written `checked = index.model().data(index, QtCore.Qt.DisplayRole).toBool()` because the result of data() is a QVariant. — Frodon, Jul 22 '13 at 09:41
Interestingly enough I did try that first, but received an error: AttributeError: 'str' object has no attribute 'toBool' so settled on the cast instead. Thanks. — C Mars, Jul 22 '13 at 10:35
On further investigation, the cast is incorrect, as it will always return True, if the value is non-zero. I have modified to checked = index.model().data(index, QtCore.Qt.DisplayRole) == 'True'. This now reflects the data correctly, but has not solved the problem completely as it still will not change. Thanks again for your comment. I will update the question. — C Mars, Jul 22 '13 at 10:52

score 18 · Answer 1 · edited Mar 08 '19 at 13:25

Here's a port of the same code above for PyQt5. Posting here as there doesn't appear to be another example of a working CheckBox Delegate in QT5, and i was tearing my hair out trying to get it working. Hopefully it's useful to someone.

from PyQt5 import QtCore, QtWidgets
from PyQt5.QtCore import QModelIndex
from PyQt5.QtGui import QStandardItemModel
from PyQt5.QtWidgets import QApplication, QTableView

class CheckBoxDelegate(QtWidgets.QItemDelegate):
    """
    A delegate that places a fully functioning QCheckBox cell of the column to which it's applied.
    """
    def __init__(self, parent):
        QtWidgets.QItemDelegate.__init__(self, parent)

    def createEditor(self, parent, option, index):
        """
        Important, otherwise an editor is created if the user clicks in this cell.
        """
        return None

    def paint(self, painter, option, index):
        """
        Paint a checkbox without the label.
        """
        self.drawCheck(painter, option, option.rect, QtCore.Qt.Unchecked if int(index.data()) == 0 else QtCore.Qt.Checked)

    def editorEvent(self, event, model, option, index):
        '''
        Change the data in the model and the state of the checkbox
        if the user presses the left mousebutton and this cell is editable. Otherwise do nothing.
        '''
        if not int(index.flags() & QtCore.Qt.ItemIsEditable) > 0:
            return False

        if event.type() == QtCore.QEvent.MouseButtonRelease and event.button() == QtCore.Qt.LeftButton:
            # Change the checkbox-state
            self.setModelData(None, model, index)
            return True

        return False


    def setModelData (self, editor, model, index):
        '''
        The user wanted to change the old state in the opposite.
        '''
        model.setData(index, 1 if int(index.data()) == 0 else 0, QtCore.Qt.EditRole)



if __name__ == '__main__':

    import sys

    app = QApplication(sys.argv)

    model = QStandardItemModel(4, 3)
    tableView = QTableView()
    tableView.setModel(model)

    delegate = CheckBoxDelegate(None)
    tableView.setItemDelegateForColumn(1, delegate)
    for row in range(4):
        for column in range(3):
            index = model.index(row, column, QModelIndex())
            model.setData(index, 1)

    tableView.setWindowTitle("Check Box Delegate")
    tableView.show()
    sys.exit(app.exec_())

score 14 · Accepted Answer · edited Jun 29 '18 at 18:55

I've found a solution for you. The trick was:

to write the setData method of the model
to always return a QVariant in the data method

Here it is. (I had to create a class called Dataframe, to make the example work without pandas. Please replace all the if has_pandas statements by yours):

from PyQt4 import QtCore, QtGui

has_pandas = False
try:
  import pandas as pd
  has_pandas = True
except:
  pass

class TableModel(QtCore.QAbstractTableModel):
    def __init__(self, parent=None, *args):
        super(TableModel, self).__init__()
        self.datatable = None
        self.headerdata = None

    def update(self, dataIn):
        print 'Updating Model'
        self.datatable = dataIn
        print 'Datatable : {0}'.format(self.datatable)
        if has_pandas:
          headers = dataIn.columns.values
        else:
          headers = dataIn.columns
        header_items = [
                    str(field)
                    for field in headers
        ]
        self.headerdata = header_items
        print 'Headers'
        print self.headerdata

    def rowCount(self, parent=QtCore.QModelIndex()):
        return len(self.datatable.index)

    def columnCount(self, parent=QtCore.QModelIndex()):
        if has_pandas:
          return len(self.datatable.columns.values)
        else:
          return len(self.datatable.columns)

    def data(self, index, role=QtCore.Qt.DisplayRole):
        if role == QtCore.Qt.DisplayRole:
            i = index.row()
            j = index.column()
            return QtCore.QVariant('{0}'.format(self.datatable.iget_value(i, j)))
        else:
            return QtCore.QVariant()

    def setData(self, index, value, role=QtCore.Qt.DisplayRole):
        if index.column() == 4:
            self.datatable.iset_value(index.row(), 4, value)
            return value
        return value

    def headerData(self, col, orientation, role):
        if orientation == QtCore.Qt.Horizontal and role == QtCore.Qt.DisplayRole:
            return '{0}'.format(self.headerdata[col])

    def flags(self, index):
        if index.column() == 4:
            return QtCore.Qt.ItemIsEditable | QtCore.Qt.ItemIsEnabled
        else:
            return QtCore.Qt.ItemIsEnabled


class TableView(QtGui.QTableView):
    """
    A simple table to demonstrate the QComboBox delegate.
    """
    def __init__(self, *args, **kwargs):
        QtGui.QTableView.__init__(self, *args, **kwargs)
        self.setItemDelegateForColumn(4, CheckBoxDelegate(self))


class CheckBoxDelegate(QtGui.QStyledItemDelegate):
    """
    A delegate that places a fully functioning QCheckBox in every
    cell of the column to which it's applied
    """
    def __init__(self, parent):
        QtGui.QItemDelegate.__init__(self, parent)

    def createEditor(self, parent, option, index):
        '''
        Important, otherwise an editor is created if the user clicks in this cell.
        ** Need to hook up a signal to the model
        '''
        return None

    def paint(self, painter, option, index):
        '''
        Paint a checkbox without the label.
        '''

        checked = index.data().toBool()
        check_box_style_option = QtGui.QStyleOptionButton()

        if (index.flags() & QtCore.Qt.ItemIsEditable) > 0:
            check_box_style_option.state |= QtGui.QStyle.State_Enabled
        else:
            check_box_style_option.state |= QtGui.QStyle.State_ReadOnly

        if checked:
            check_box_style_option.state |= QtGui.QStyle.State_On
        else:
            check_box_style_option.state |= QtGui.QStyle.State_Off

        check_box_style_option.rect = self.getCheckBoxRect(option)

        # this will not run - hasFlag does not exist
        #if not index.model().hasFlag(index, QtCore.Qt.ItemIsEditable):
            #check_box_style_option.state |= QtGui.QStyle.State_ReadOnly

        check_box_style_option.state |= QtGui.QStyle.State_Enabled

        QtGui.QApplication.style().drawControl(QtGui.QStyle.CE_CheckBox, check_box_style_option, painter)

    def editorEvent(self, event, model, option, index):
        '''
        Change the data in the model and the state of the checkbox
        if the user presses the left mousebutton or presses
        Key_Space or Key_Select and this cell is editable. Otherwise do nothing.
        '''
        print 'Check Box editor Event detected : '
        print event.type()
        if not (index.flags() & QtCore.Qt.ItemIsEditable) > 0:
            return False

        print 'Check Box editor Event detected : passed first check'
        # Do not change the checkbox-state
        if event.type() == QtCore.QEvent.MouseButtonPress:
          return False
        if event.type() == QtCore.QEvent.MouseButtonRelease or event.type() == QtCore.QEvent.MouseButtonDblClick:
            if event.button() != QtCore.Qt.LeftButton or not self.getCheckBoxRect(option).contains(event.pos()):
                return False
            if event.type() == QtCore.QEvent.MouseButtonDblClick:
                return True
        elif event.type() == QtCore.QEvent.KeyPress:
            if event.key() != QtCore.Qt.Key_Space and event.key() != QtCore.Qt.Key_Select:
                return False
        else:
            return False

        # Change the checkbox-state
        self.setModelData(None, model, index)
        return True

    def setModelData (self, editor, model, index):
        '''
        The user wanted to change the old state in the opposite.
        '''
        print 'SetModelData'
        newValue = not index.data().toBool()
        print 'New Value : {0}'.format(newValue)
        model.setData(index, newValue, QtCore.Qt.EditRole)

    def getCheckBoxRect(self, option):
        check_box_style_option = QtGui.QStyleOptionButton()
        check_box_rect = QtGui.QApplication.style().subElementRect(QtGui.QStyle.SE_CheckBoxIndicator, check_box_style_option, None)
        check_box_point = QtCore.QPoint (option.rect.x() +
                            option.rect.width() / 2 -
                            check_box_rect.width() / 2,
                            option.rect.y() +
                            option.rect.height() / 2 -
                            check_box_rect.height() / 2)
        return QtCore.QRect(check_box_point, check_box_rect.size())


###############################################################################################################################
class Dataframe(dict):
  def __init__(self, columns, values):
    if len(values) != len(columns):
      raise Exception("Bad values")
    self.columns = columns
    self.values = values
    self.index = values[0]
    super(Dataframe, self).__init__(dict(zip(columns, values)))
    pass

  def iget_value(self, i, j):
    return(self.values[j][i])

  def iset_value(self, i, j, value):
    self.values[j][i] = value


if __name__=="__main__":
    from sys import argv, exit

    class Widget(QtGui.QWidget):
        """
        A simple test widget to contain and own the model and table.
        """
        def __init__(self, parent=None):
            QtGui.QWidget.__init__(self, parent)

            l=QtGui.QVBoxLayout(self)
            cdf = self.get_data_frame()
            self._tm=TableModel(self)
            self._tm.update(cdf)
            self._tv=TableView(self)
            self._tv.setModel(self._tm)
            for row in range(0, self._tm.rowCount()):
                self._tv.openPersistentEditor(self._tm.index(row, 4))
            self.setGeometry(300, 300, 550, 200)
            l.addWidget(self._tv)

        def get_data_frame(self):
            if has_pandas:
              df = pd.DataFrame({'Name':['a','b','c','d'],
              'First':[2.3,5.4,3.1,7.7], 'Last':[23.4,11.2,65.3,88.8], 'Class':[1,1,2,1], 'Valid':[True, False, True, False]})
            else:
              columns = ['Name', 'First', 'Last', 'Class', 'Valid']
              values = [['a','b','c','d'], [2.3,5.4,3.1,7.7], [23.4,11.2,65.3,88.8], [1,1,2,1], [True, False, True, False]]
              df = Dataframe(columns, values)
            return df

    a=QtGui.QApplication(argv)
    w=Widget()
    w.show()
    w.raise_()
    exit(a.exec_())

Yes I had come to a similar solution after fixing the data reflection. The set data method is the obvious culprit. Your approach looks fine so am happy to accept your answer. A couple of improvements can be made. For example I did not like the solution of making the setData() and flags() functions column specific, but it should not be to hard to code around this. — C Mars, Jul 23 '13 at 08:36
`AttributeError: 'NoneType' object has no attribute 'toBool'`. Lots of other warnings came up, this should probably be retooled, especially to fit PySide which doesn't use QVariants... — eric, Jul 16 '15 at 21:25
Trying to adapt to qstandarditemmodel, and only one checkbox is showing, have posted follow-up question: http://stackoverflow.com/questions/31478121/view-qstandarditemmodel-with-column-of-checkboxes-in-pyside-pyqt — eric, Jul 17 '15 at 17:20
Is the else block in the `QtCore.QEvent.KeyPress` block there on purpose and what is it supposed to do? — Tim, Jun 29 '18 at 09:05
I think it's a typo. The else block should return True (as far as I can remember the script) — Frodon, Jun 29 '18 at 09:31
@Frodon I just figured it out. The indent is incorrect and the else block should belong to the `event.type()` checks. Otherwise you see activations during mouse movements. Unfortunately I had to make some more (nonsensical) changes to fullfill StackOverflow's 6-character limit. — Tim, Jun 29 '18 at 11:29

score 4 · Answer 3 · answered Sep 24 '13 at 14:06

4

I added

if event.type() == QEvent.MouseButtonPress or event.type() == QEvent.MouseMove:
      return False

to prevent checkbox from flickering when moving the mouse

answered Sep 24 '13 at 14:06

user2811449

51
2

PyQt - Column of Checkboxes in a QTableView

3 Answers3

Linked