iterate through treeview (QAbstractItemModel) of an older topic (see link)

MaMo

The code above in an older topic discribes nearly what I need. But now my question to it: how can I iterate over all items of the tree when it has been created?

e.g. to write data of the tree to a csv file

JonB

@MaMo
You should (probably) write a recursive function to descend the tree depth-first, taking into account that tree models have indexes which require you to pass the correct parent. have a read of https://doc.qt.io/qt-6/qmodelindex.html#details and https://doc.qt.io/qt-6/model-view-programming.html#navigation-and-model-index-creation.

You might be able to get a list of all the indexes via https://doc.qt.io/qt-6/qabstractitemmodel.html#match with something like:

QModelIndexList matches =  model->match(rootIndex, Qt::DisplayRole, "", -1, Qt::MatchFlags(Qt::MatchStartsWith | Qt::MatchRecursive));

[Just seen you are Python, so Python equivalent.] But this pre-generates the entire list, and per the docs we are not sure what order it comes out in. I prefer the self-coded recursive approach.

Be aware that writing to a CSV file will produce a flat output, i.e. you will not know where items are in the tree hierarchy, two adjacent items might be siblings, parent->child, or child->parent. If you don't care about that it's fine, if you do care you will need to output some extra column into the CSV to indicate parent/childhood.

SGaist

Hi,

I concur with @JonB, a CSV file does not fit a tree view data structure. JSON or XML would be a better choice.

MaMo

Csv was just an example. whether i export it as csv or xml doesn't matter for now. My problem at the moment is to get all the data from the treeview, e.g. after clicking on a button → unfortunately i can't do that.

JonB

@MaMo said in iterate through treeview (QAbstractItemModel) of an older topic (see link):

unfortunately i can't do that.

I suspect you mean, or should mean, from the model rather than from the QTreeView. Presumably all the information you want is in the model; QTreeView is a QWidget (and complex at that), I don;t think you will want to extract its information.

So I suggested above how to go about getting the information from the model. You just need to write the code for what you want.

MaMo

@JonB
And how exactly do i get the model for the example above when I click on a button in Python??

jsulm

@MaMo said in iterate through treeview (QAbstractItemModel) of an older topic (see link):

And how exactly do i get the model for the example above when I click on a button in Python??

Well, you're creating the model, right? So, just store it as member variable.

JonB

@MaMo
As @jsulm says, you created the model, right? So you can keep it in a member variable of whatever UI class you are in, perhaps where the QTreeView is, perhaps it's your QMainWindow or something. Or, wherever it is, you set it via QTreeView.setModel() so you can always retrieve it via QTreeView.model().