Model-view checkstate signal

[JonB]

@Pl45m4
I had posted mine before I saw yours. So OP already has in setData() when CheckStateRole changes: self.dataChanged.emit(index, index, [role]). He can use that, which I think is what you are saying.

[blossomsg]

Hello,

@JonB and @Pl45m4 thank you for the brief info.
correct me if i am wrong, just rephrasing above for clarity

@JonB said in Model-view checkstate signal:

I am not sure I understand what you mean by this.

what i am looking for is, how we connect QCheckBox.clicked.connect(<function>) , same logic or for something similar in MVC, whichever index i click should do something(that something would be in a function)

This would be a bad practice if i try signaling a function.
@Pl45m4 said in Model-view checkstate signal:

I think OP is looking for some kind of 1to1 connection in the model/view, between the checkable item (which is not directly a QCheckBox) and some receiver of the signal... which kinda destroys or bypasses a clean MV(C) structure...

If I need to try such a thing i can do it with dataChanged.emit in the setData, but again this would be a bad practice, correct?

[Pl45m4]

@blossomsg

That's why I wrote:

@Pl45m4 said in Model-view checkstate signal:

You can't connect directly to that checkbox.
Either you use the dataChanged(...) signal when the data is, well, changed and compare the QModelIndex (row, col) or you add your own logic when you set your data.

So, use the dataChanged signal, which is already there and sort out the correct model index + value.

[blossomsg]

noted.
if possible can you provide a code snippet, just for understanding connections?
It would be helpful
Thank You.

[Pl45m4]

@blossomsg said in Model-view checkstate signal:

if possible can you provide a code snippet, just for understanding connections?

Code for what? Who made your first (the QCheckBox) example? There you already have similar code.
Now you just need to use your model's dataChanged(...) signal and figure out what index your checkbox has, depending on its row and column.
Or you implement your own setData logic and emit your custom signal there

[SGaist]

Hi,

A model can have multiple views and a view does not necessarily mean a QWidget.

As my fellow already wrote: use your model.
Rather than creating it as part of the setModel call, create it before and keep a reference to it. Then connect its dataChanged signal to the slot you want to use it with. The only thing you have to do is extract the information you want to act accordingly.

[blossomsg]

Hello All,
I have tried a version as suggested to connect directly with dataChage in the model
getting the expected result, can you review and let me know, if there is a better way to do it.
I have added # NEW to those lines and functions

from PySide6 import QtCore, QtGui


class LModel1(QtCore.QAbstractListModel):
    def __init__(self, data: list[str], parent=None):
        super().__init__(parent)
        self._data = data
        # from ai claude and fluent python - dict Comprehensions - pg: 79
        self._check_states = {item: QtCore.Qt.CheckState.Unchecked for item in self._data}

    def data(self, index, /, role=...):
        if not index.isValid():
            return None

        item = self._data[index.row()]

        if role == QtCore.Qt.ItemDataRole.DisplayRole:
            return item

        if role == QtCore.Qt.ItemDataRole.CheckStateRole:
            return self._check_states[item]

        if role == QtCore.Qt.ItemDataRole.DecorationRole:
            pixmap = QtGui.QPixmap(10, 10)
            pixmap.fill(QtCore.Qt.transparent)
            painter = QtGui.QPainter(pixmap)
            painter.setRenderHint(QtGui.QPainter.Antialiasing)
            painter.setBrush(QtGui.QColor("red"))
            painter.drawRect(pixmap.rect())
            painter.end()
            return QtGui.QIcon(pixmap)

        if role == QtCore.Qt.ItemDataRole.ToolTipRole:
            return item

        if role == QtCore.Qt.ItemDataRole.FontRole:
            font = QtGui.QFont("Cursive", 12)
            font.bold()
            return font

        return None

    def setData(self, index, value, /, role=...):
        if not index.isValid():
            return None

        item = self._data[index.row()]

        if role == QtCore.Qt.ItemDataRole.CheckStateRole:
            self._check_states[item] = value
            self.dataChanged.connect(self.print_something)  # NEW
            self.dataChanged.emit(index, index, [role])
            return True
        return None

    def flags(self, index, /):
        if not index.isValid():
            return None

        return QtCore.Qt.ItemFlag.ItemIsUserCheckable | QtCore.Qt.ItemFlag.ItemIsEnabled | QtCore.Qt.ItemFlag.ItemIsSelectable

    def rowCount(self, /, parent=...):
        return len(self._data)

    def print_something(self, index):  # NEW
        item = self._data[index.row()]
        if self._check_states[item] == QtCore.Qt.CheckState.Checked.value:
            print("something")
            return "something"
        elif self._check_states[item] == QtCore.Qt.CheckState.Unchecked.value:
            print("something else")
            return "something else"
        return None

[jsulm]

@blossomsg A slot usually does not return anything

[blossomsg]

Noted. This is just for testing, if it works according to check/uncheck values(0 and 2).
But the end goal is to add a function which will be loading/unloading obj in autodesk maya.
But is this in the right direction?

[blossomsg]

one more thing
I even tested on claude ai - it even suggested we can addself.model=LModel1 in class LView1 and then do the signal in the view, just curious is that okay as well?

[SGaist]

@blossomsg There's no reason for that slot to be in the model.

Depending on how you want to integrate that with Maya, create your own custom view on top of the model that will translate that information in whatever is needed for Maya.
A "view" does not mandatory mean a tree or a table, it's really whatever uses the model as a source of information.