How to properly manage checkbox states with signal-slot connections in qt?

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C++

QT

Hello! I'm working on a Qt application where I need to manage the state of multiple checkboxes in a QTreeView model. I have a "Select All" checkbox (select_all_checkbox) outside of the tree view that should toggle the state of all items in the model. Additionally, the state of the "Select All" checkbox should reflect whether all, some, or none of the items are checked.

Here's what I have so far:

1. Checkbox Logic:
When select_all_checkbox is checked, all items in the tree view should be set to checked.
When select_all_checkbox is unchecked, all items should be unchecked.
If only some items are checked, select_all_checkbox should show a partially checked state.

2. Signal-Slot Connections:
I am connecting the stateChanged(int) signal of select_all_checkbox to a slot on_select_all_state_changed(int state).
I am also connecting the itemChanged(QStandardItem*) signal of my model to a custom slot on_model_item_changed(QStandardItem* item).

What I have tried:

void WIDGET::create_signals()
{
    connect(m_ui->select_all_checkbox, SIGNAL(stateChanged(int)), this, SLOT(on_select_all_state_changed(int)));
    connect(model, SIGNAL(itemChanged(QStandardItem*)), this, SLOT(on_model_item_changed(QStandardItem*)));
}

void WIDGET::on_select_all_state_changed(int state)
{
    if (model) 
    {
        //disconnect(model,SIGNAL(itemChanged(QStandardItem*)), this, SLOT(on_checkbox_state_changed()));
        model->blockSignals(true);
        for (int row = 0; row < model->rowCount(); ++row) 
        {
            item = model->item(row, 1); 
            if (item) 
            {
                if (state == Qt::Checked) 
                {
                    item->setCheckState(Qt::Checked);
                } 
                else if (state == Qt::Unchecked)
                {
                    item->setCheckState(Qt::Unchecked); 
                }
            }
        }
        afcq_safe_connect(model,SIGNAL(itemChanged(QStandardItem*)), this, SLOT(on_checkbox_state_changed()));
        //model->blockSignals(false);
        m_ui->m_run_tests_button->setEnabled(state == Qt::Checked);
        on_checkbox_state_changed();
    }
    
}

void WIDGET::on_checkbox_state_changed()
{
    //disconnect(m_ui->select_all_checkbox , SIGNAL(stateChanged(int)), this, SLOT(on_select_all_state_changed(int)));
    
    m_ui->select_all_checkbox ->blockSignals(true);
    bool anyChecked = false;
    bool allChecked = true; // Start with true and set to false if any unchecked item is found

    for (int row = 0; row < model->rowCount(); ++row) 
    {
        item = model->item(row, 1);
        if (item) 
        {
            if (item->checkState() == Qt::Checked)
            {
                anyChecked = true; // At least one item is checked
            }
            else
            {
                allChecked = false; // Found an unchecked item
            }
        }
    }
    
    if (allChecked) 
    {
        m_ui->select_all_checkbox ->setCheckState(Qt::Checked);
    } 
    else if (anyChecked) 
    {
        m_ui->select_all_checkbox ->setCheckState(Qt::PartiallyChecked);
    } 
    else 
    {
        m_ui->select_all_checkbox ->setCheckState(Qt::Unchecked);
    }

    m_ui->select_all_checkbox ->update();

    //afcq_safe_connect(m_ui->select_all_checkbox, SIGNAL(stateChanged(int)), this, SLOT(on_select_all_state_changed(int)));
    m_ui->select_all_checkbox ->blockSignals(false);
    m_ui->run_tests_button->setEnabled(anyChecked);  
}

The Problem:

When I uncheck the m_select_all_checkbox, the items do not get unchecked as expected.
Also, I occasionally run into recursive signal-slot issues or the "Select All" checkbox not reflecting the correct state of the items.

Questions:

1.Is my approach to using blockSignals() correct, or is there a better way to handle signal-slot connections for this case?
2.How can I ensure that all items are unchecked when m_select_all_checkbox is unchecked?
3.Are there any best practices for managing the states of multiple checkboxes and a "Select All" checkbox in Qt that I should follow?

Any advice or suggestions to improve my implementation would be greatly appreciated!

Thank you in advance for your help!