Get QModelIndex in delegate

VRonin

In general, this is very easy as Qt already has a role to save the CheckboxState (Qt::CheckStateRole) so you just need the last part of this wiki article to read/write that role

The problem here is that QFileSystemModel can't handle Qt::CheckStateRole.
To overcome this problem you need a proxymodel between your model and the view that takes care of the roles that QFileSystemModel doesn't manage.

I worked on such a solution in my spare time and, while I can't guarantee 100% stability you can find it here under the name RoleMaskProxyModel. I haven't developed examples for it yet but the test method tst_RoleMaskProxyModel::testUseRoleMask should give you an idea of the usage

maxwell31

Adding a role to QFileSystemModel should also not be difficult. However, to set the initial state I guess I must once walk through the whole model, right? Or can one set a default state for a role?

VRonin

@maxwell31 said in Get QModelIndex in delegate:

Adding a role to QFileSystemModel should also not be difficult.

It's not only if you either use the privates of Qt or recompile a custom Qt widgets model

However, to set the initial state I guess I must once walk through the whole model, right?

Normally yes

Or can one set a default state for a role?

You could in the subclass but in this case it is probably easier to handle the default state directly in the delegate

maxwell31

Hm, so no easy solution :-(

maxwell31

What about getting the QModelIndex inside the delegate, that would be easy if possible

maxwell31

Actually I found how to get the index:

  fileSystemModel.index(model.urlstringrole,0)

where filesystemmodel is

 engine.rootContext()->setContextProperty("fileSystemModel", fsm);

and fsm the QFileSystemModel

maxwell31

Now I would only need to find out how to set a property of my TableViewColumn delegate, e.g. for the onSortIndicatorChanged signal of my view.

I have a isChecked(QModelIndex) function in my model. If I can loop over the displayed delegates, I could update their checked state, but I don't know how to do this

Edit: Hm, fileSystemModel.index(model.urlstringrole,0) seems to give the wrong index

VRonin

What you are doing is flaky at best. Please read that wiki page I linked especially in the section "Using the data in QML"

maxwell31

:-) Yes, I have the feeling that it is flaky at best. But is there really no way to get the QModelIndex right? I found that using a Connection to the delegate should work, but my problem is still getting the right QModelIndex for a delegate

maxwell31

Is there something like a

  modelAdaptor.mapRowToModelIndex

function accessible?

maxwell31

As I do not yet understand the solution @VRonin has in his repository, I thought about a hacky solution:

Keep a list of persistent model indexes in a QFileSystemModel derived model, add a IsChecked Role to the derived model and set the data function for this role to

        case IsCheckedRole:
            return isChecked(QPersistentModelIndex(index));

a custom function, which will check, whether index is in the persistentModel Index list.

This brought to my mind, that I don't actually know how this works. If in the delegate I then use this role to set the checked property of a checkbox, how does the delegate now if the model is updated? It seems to work though - but not completly:

If I select an item, sort by the name column, deselect it and sort again, the item is selected again. I guess this has nothing todo with my isChecked function. A similar thing is if I only add a checkbox to the delegate and do nothing in the model. If I select it, and then sort, the item which goes to its place due to sorting is selected.