where to call beginRemoveRows() when QAbstractItemModel is deleted from somewhere else

gde23

Hello,

I have a model view that derives from QAbstractItemModel.
The items in the view are a list of open windows and derive from QMainWindow as well as my item class for the modelview.

to close one of those the windows, the item deletes itself from the model, however since I do not interact with the ItemModel/ItemView directly I don't know where to call beginRemoveRows() endRemoveRows().

Any ideas?

VRonin

@gde23 said in where to call beginRemoveRows() when QAbstractItemModel is deleted from somewhere else:

the item deletes itself from the model

How? Can you show the code?

gde23

@VRonin
Thanks for the fast answer.
Here is the destructor of the item:

AbstractPlot::~AbstractPlot()
{   
    // remove item from parent-item (its a tree-model)
    if(m_parent_item != NULL)
    {
        for(size_t c=0; c<m_parent_item->getChildCount(); c++) {
            if(m_parent_item->getChild(c) == this) {
                m_parent_item->eraseChild(c);
            }
        }
    }
    // delete other stuff
}

the eraseChild() method just removes the child from the vector containing the child items

void Item::eraseChild(const size_t index)
{
    m_child_items.erase(m_child_items.begin() + index);
}

SGaist

Hi,

Is it me or are you children items responsible for their own deletion from their parents ?

gde23

Hi,

yes. At the moment it's the children being responsible for this. When the child destructor is called the item deletes the entry from the parent, but maybe it's a bad idea to implement it that way?

EDIT:

Ok i got it working somehow.

I added two slots to the Model that have to be called from the item that wants to delete itself before it commits suicide.

void MyModel::slotBeginRemoveItem(TreeItem* item)
{
    QModelIndex ind = pointer2ModelIndex(item);
    QModelIndex parent = ind.parent();
    beginRemoveRows(parent, ind.row(), ind.row());
}

void MyModel::slotEndRemoveItem()
{
    endRemoveRows();
}

The destructor of the item now loks like this

TreeItem::~TreeItem()
{
    emit signalBeginRemoveItem(static_cast<TreeItem*>(this));
    if(getParentItem() != NULL)
    {
        getParentItem()->eraseChild(this);
    }
    emit signalEndRemoveItem();
    // other delete stuff
}

SGaist

Not a good idea indeed. Why would the item have to know anything about what stores it ?