I have a QTableView containing a column with checkboxes. I use a delegate for the checkbox because I want to align it in the center of the column. The one which is generated via the CheckStateRole isn’t. The checkbox editor is made permanent for this column.

To sort and filter the table I use a QSortFilterProxyModel. Sorting works and filtering with wildcards also. But if I remove the wildcard filter, the checkboxes of the formerly filtered rows are not drawn. Instead the column shows 0 or 1.

The code is:

import sys
import pandas as pd
from PySide6.QtCore import Qt, Property, Signal, QAbstractTableModel
from PySide6.QtCore import QSortFilterProxyModel, QSignalBlocker
from PySide6.QtWidgets import (QCheckBox, QHBoxLayout, QStyledItemDelegate,
                               QTableView, QWidget, QApplication, QMainWindow,
                               QVBoxLayout, QLineEdit, QFrame)


class CenterCheckBox(QWidget):
    toggled = Signal(bool)

    def __init__(self, parent):
        super().__init__(parent)
        layout = QHBoxLayout(self)
        layout.setContentsMargins(0, 0, 0, 0)
        self.check = QCheckBox()
        layout.addWidget(self.check, alignment=Qt.AlignmentFlag.AlignCenter)
        self.check.setFocusProxy(self)
        self.check.toggled.connect(self.toggled)
        # set a 0 spacing to avoid an empty margin due to the missing text
        self.check.setStyleSheet('color: red; spacing: 0px;')
        self.setAutoFillBackground(True)

    @Property(bool, user=True)   # note the user property parameter
    def checkState(self):
        return self.check.isChecked()

    @checkState.setter
    def checkState(self, state):
        with QSignalBlocker(self.check) as blocker:
            self.check.setChecked(state)


class MyCheckboxDelegate(QStyledItemDelegate):
    def __init__(self, parent):
        super().__init__(parent)

    def createEditor(self, parent, option, index):
        check = CenterCheckBox(parent)
        check.toggled.connect(lambda: self.commitData.emit(check))
        return check

    def setModelData(self, editor, model, index):
        model.setData(index, editor.checkState)


class TableModel(QAbstractTableModel):
    def __init__(self, data):
        super().__init__()
        print(data)
        self._data = data

    def rowCount(self, index=None):
        return self._data.shape[0]

    def columnCount(self, parent=None):
        return self._data.shape[1]

    def data(self, index, role=Qt.ItemDataRole.DisplayRole):
        if index.isValid():
            if role == Qt.ItemDataRole.DisplayRole or role == Qt.ItemDataRole.EditRole:
                if self._data.columns[index.column()]=='Delete':
                    return ''
                value = self._data.iloc[index.row(), index.column()]
                return str(value)


class MyWindow(QMainWindow):
    def __init__(self, *args):
        QMainWindow.__init__(self, *args)
        self.frame = QFrame(self)
        self.verticalLayout = QVBoxLayout(self.frame)
        self.lineEdit = QLineEdit(self.frame)
        self.verticalLayout.addWidget(self.lineEdit)
        self.table_view = QTableView(self.frame)
        self.verticalLayout.addWidget(self.table_view)

        table_model = TableModel(pd.DataFrame([['1', '1'],
                                               ['0', '0'],
                                               ['2', '0']]))
        proxy_model = QSortFilterProxyModel()
        proxy_model.setSourceModel(table_model)
        self.table_view.setModel(proxy_model)
        self.table_view.setSortingEnabled(True)
        self.lineEdit.textChanged.connect(proxy_model.setFilterWildcard)

        self.table_view.setItemDelegateForColumn(1, MyCheckboxDelegate(self))
        for row in range(0, proxy_model.rowCount()):
            self.table_view.openPersistentEditor(proxy_model.index(row, 1))

        self.setCentralWidget(self.frame)


app = QApplication(sys.argv)
window = MyWindow()
window.show()
sys.exit(app.exec())

I already searched in internet for such a behaviour, but nothing found. What I can do to see the checkboxes again after clearing the wildcard filter? May be to call openPersistentEditor again, but how to know when?

BTW:
Is there a description of the interaction between delegates, views, models and so on?
Until now I only found documentation about the classes and a very basic description
of the model view architecture.