Unable to add a QCompleter to a QCombobox in PyQt5

Hi,

I have the following code:

Code:

import sys
from functools import partial
from typing import Optional
 
from PyQt5 import QtCore
from PyQt5.QtCore import QAbstractTableModel, QModelIndex, QObject, QSortFilterProxyModel, QVariant, \
    Qt
from PyQt5.QtWidgets import QAbstractItemView, QApplication, QComboBox, QHBoxLayout, QLabel, QTableView, \
    QWidget
 
 
class MyModel(QAbstractTableModel):
 
    def __init__(self, parent: Optional[QObject] = None) -> None:
        super().__init__(parent=parent)
 
        self.headers = ['Nummer', 'Name', 'Gemeinde']
        self.data = [
            ('010006', 'Alt Duvenstedt', 'Alt Duvenstedt'),
            ('010010', 'Altenhof', 'Altenhof'),
            ('010012', 'Altwickenbeck (Neuw)', 'Neuwittenbeck'),
            ('010021', 'Bargstedt', 'Bargstedt'),
            ('010023', 'Barkelsby', 'Barkelsby'),
            ('010024', 'Basdorf (Rie)', 'Rieseby'),
        ]
 
    def headerData(self, section: int, orientation: Qt.Orientation, role: int = ...):
        if orientation == Qt.Horizontal and role == Qt.DisplayRole:
            return self.headers[section]
 
    def columnCount(self, parent: QModelIndex = ...) -> int:
        return len(self.headers)
 
    def rowCount(self, parent: QModelIndex = ...) -> int:
        return len(self.data)
 
    def data(self, index: QModelIndex, role: int = ...):
        if role == Qt.DisplayRole:
            return self.data[index.row()][index.column()]
        return QVariant()
 
 
class MyCombobox(QComboBox):
 
    def __init__(self, parent: Optional[QWidget] = None) -> None:
        super().__init__(parent=parent)
 
        self.setFocusPolicy(Qt.StrongFocus)
        # self.setEditable(True)
 
        # self.filterModel = QSortFilterProxyModel(self)
        # self.filterModel.setFilterCaseSensitivity(Qt.CaseInsensitive)
 
        self.tableView = QTableView(self)
        self.setView(self.tableView)
        self.tableView.setSelectionMode(QAbstractItemView.SingleSelection)
        self.tableView.setSelectionBehavior(QAbstractItemView.SelectRows)
        self.tableView.setSortingEnabled(True)
        self.tableView.setAutoScroll(False)
        self.tableView.horizontalHeader().setStretchLastSection(True)
        self.tableView.verticalHeader().hide()
 
        # self.completer = QCompleter(self)
        # self.completer.setCompletionMode(QCompleter.UnfilteredPopupCompletion)
        # self.completer.setPopup(self.tableView)
        # self.completer.setModel(self.filterModel)
        # self.setCompleter(self.completer)
 
        # self.lineEdit().textEdited.connect(self.filterModel.setFilterFixedString)
        # self.completer.activated.connect(self.onCompleterActivated)
 
    def setModel(self, model: QtCore.QAbstractItemModel) -> None:
        super().setModel(model)
        # self.filterModel.setSourceModel(model)
        # self.completer.setModel(self.filterModel)
 
        self.tableView.resizeColumnsToContents()
        self.tableView.resizeRowsToContents()
        self.tableView.setMinimumWidth(self.tableView.horizontalHeader().length())
        self.setMinimumWidth(100)
 
    def setModelColumn(self, column):
        super().setModelColumn(column)
        # self.filterModel.setFilterKeyColumn(column)
        # self.completer.setCompletionColumn(column)
 
    # def onCompleterActivated(self, text):
    #     if text:
    #         index = self.findText(str(text))
    #         self.setCurrentIndex(index)
 
 
def setModelIndex(index: int, target: QComboBox):
    target.blockSignals(True)
    target.setCurrentIndex(index)
    target.blockSignals(False)
 
 
if __name__ == '__main__':
    app = QApplication(sys.argv)
 
    model = MyModel()
    sortModel = QSortFilterProxyModel()
    sortModel.setFilterCaseSensitivity(Qt.CaseInsensitive)
    sortModel.sort(1, Qt.AscendingOrder)
    sortModel.setSourceModel(model)
 
    combobox = MyCombobox()
    combobox.setModel(sortModel)
    combobox.setModelColumn(0)
 
    combobox2 = MyCombobox()
    combobox2.setModel(sortModel)
    combobox2.setModelColumn(1)
 
    combobox.currentIndexChanged.connect(partial(setModelIndex, target=combobox2))
    combobox2.currentIndexChanged.connect(partial(setModelIndex, target=combobox))
 
    widget = QWidget()
    layout = QHBoxLayout()
    layout.addWidget(QLabel('Nummer'))
    layout.addWidget(combobox)
    layout.addWidget(QLabel('Name'))
    layout.addWidget(combobox2)
    layout.addStretch(10)
 
    widget.setWindowTitle('Synchronized comboboxes with shared model')
    widget.setFixedWidth(500)
    widget.setLayout(layout)
    widget.show()
 
    sys.exit(app.exec_())

I have a model which is shared between two comboboxes.
If I select an entry in one combobox, the other combobox should be updated accordingly.
This works fine when the combobox is not set editable.

As soon as I set it editable (uncommenting the code), I am unable to fill the combobox correctly.

There a several issues I don't understand:

The tableview can not be used twice (I guess I have to duplicate the code and create two instances of a tableview, one for the combobox itself and one for the completer?)
If I select something in the tableview of the combobox, the lineedit is not updated
If I connect the textEdited signal of the lineedit and try to change the index "manually", the changes still are not reflected in the combobox.

I removed all completer code as well and only wanted to have an editable combobox with a tableview, but this does not work as well. Only if I set editable to False I have a working combobox again (selecting something in the tableview will set the index and display the correct text).

What am I doing wrong? I can't figure out what the problem is.

The code above should be a working example with two synched readonly comboboxes.
I just want to add autocompletion / filtering to both of them, because this tableview will contain thousands of items later on.