QStandardItemModel doesn't update QTableView

demberto

class EventsTableModel(QStandardItemModel):
    EVENT = 1000

    def __init__(self, et: EventTree, show_only: list[EventEnum]) -> None:
        super().__init__(None)
        self.et = et
        self.events = tuple(et.get(*show_only))
        self.set_horizontal_header_labels(["ID", "Value"])

        for event in self.events:
            id_item = QStandardItem(str(event.id))
            id_item.set_editable(False)
            val_item = QStandardItem()
            val_item.set_data(event, self.EVENT)

            try:
                val_item.set_data(event.value, Qt.ItemDataRole.DisplayRole)
            except NotImplementedError:
                continue
            self.append_row((id_item, val_item))

    def set_data(self, index: QModelIndex, value, role: int = ...) -> bool:
        event = index.data(self.EVENT)
        try:
            event.value = value
        except Exception as exc:
            logging.exception(exc)
            return False
        else:
            self.dataChanged.emit(index, index)  # type: ignore
            return True

When I try to enter a new value in a cell's editor and press Enter, the new value doesn't appear in the cell. This occurs even if there are no exceptions.

I am using a normal QTableView instance for this model. The data gets correctly displayed initially after loading.

PySide: 6.4.2

EDIT: Fixed it by adding this line before emitting dataChanged :

self.item_from_index(index).set_data(value, Qt.ItemDataRole.DisplayRole)

JonB

@demberto
Your set_data() method does not use the role parameter passed to it, which it should, or you should not have it accept such a parameter.
If you do make it use the parameter, you should be passing Qt.ItemDataRole.EditRole not DisplayRole.

demberto

@JonB Do you mean the place where I call self.item_from_index(index).set_data(value, Qt.ItemDataRole.DisplayRole)?

OR do you mean this?

def set_data(self, index: QModelIndex, value, role: int = ...) -> bool:
        event = index.data(self.EVENT)
        try:
            event.value = value
        except Exception as exc:
            logging.exception(exc)
            return False
        else:
            self.item_from_index(index).set_data(value, role)
            self.dataChanged.emit(index, index)  # type: ignore
            return True

EDIT: That works
I still don't understand why I have to call self.item_from_index(index).set_data(value, role) explicitly. Isn't that what set_data mechanism is supposed to do internally, or I should call super-class set_data in my else clause?

JonB

@demberto
Yes, you should call base QStandardItemModel.setData() to handle the case you don't.

Your code is bad for the normal, successful case. You do not return True, you just drop off the end of the method and Python will doubtless return None/False, could be a problem.

The base setData() defaults role = EditRole for the parameter. You really ought do so too.

Where you call it you show self.item_from_index(index).set_data(value, Qt.ItemDataRole.DisplayRole). That should really be EditRole, or you can omit it if you change to default as per previous point.

demberto

@JonB Finally:

Your code is bad for the normal, successful case. You do not return True, you just drop off the end of the method and Python will doubtless return None/False, could be a problem.

def set_data(self, index: QModelIndex, value, role: int = Qt.ItemDataRole.EditRole) -> bool:
        event = index.data(self.EVENT)
        try:
            event.value = value
        except Exception as exc:
            logging.exception(exc)
            return False
        else:
            super().set_data(index, value, role)
        return True

Thanks!

JonB

@demberto
No need for else: IMHO :) Now you hide if the base class setData() were to fail. To me

return super().set_data(index, value, role)

as the final line makes sense.