How to show all the children items in QTreeView?

Question

I tried to create a QTreeView as example from Qt

http://doc.qt.io/qt-5/qtwidgets-itemviews-editabletreemodel-example.html

When we click on the triangle before each "parent" item, the "children" items will be shown.

In my case I add this line to tree view

 myTreeView->setRootIsDecorated(false);

As the result, there is no more triangle before each "parent" item.

But the "children" items are also not shown any more.

My requirements are:

disable the triangle before each "parent" item
show ALL items in the tree, both "parent" and "children"

How can I do it?

Make shure to call that method every time you change the model data — Felix
@G.M. I think it would be useful to post your solution as an answer, so question can be closed and it get well documented for future visitors — cbuchart

G.M. G.M. · Accepted Answer · 2018-09-10T08:44:54

As per the comment you can programmatically ensure all items in the tree are visible by calling QTreeView::expandAll...

myTreeView->expandAll();

Note that it may need to be called again as/when child items are added to the model which, depending on the size of the model, could become a performance bottleneck.

As an alternative, it might be better to inherit from QTreeView and override the QTreeView::rowsInserted member.

virtual void MyTreeView::rowsInserted (const QModelIndex &parent, int start, int end) override
  {

    /*
     * Let the base class do what it has to.
     */
    QTreeView::rowsInserted(parent, start, end);

    /*
     * Make sure the parent model index is expanded.  If it already
     * is expanded then the following should just be a noop.
     */
    expand(parent);
  }

This should give better performance for large models.

How to show all the children items in QTreeView?

1 Answers