Model with two very different views

[mholmes]

I'm trying to imagine how to implement a rather unusual model/view situation. I'm trying to provide two distinct views of an XML hierarchy:

1. A hierarchical tree view, using QTreeView.

2. A list view, based on QStringListModel, which shows a list of the nodes which have xml:id attributes, along with some text from those nodes, displayed in a QListView.

I can do each of these things separately -- in other words, I can implement a model based on QAstractItemModel, construct a tree in it, and display the tree in a QTreeView; and I can construct a model based on QStringListModel consisting of a list of the xml:ids, and display this in a QListView. But what I'd really like to do is have a single model which is hooked up to both a QTreeView and a QListView, so that any change to the model is simultaneously displayed in both controls.

Is this possible? If so, how would you go about it?

All help appreciated,
Martin

[faldzip]

Use a proxy model, either QSortFilterProxyModel (or derive a class from it) or make your own proxy model from scratch by subclassing QAbstractProxyModel.
This proxy model is between a model and a view, so in your case it will filter out any other nodes than xml:id from your base XML model.
In Qt docs you can found two examples demonstrating use of QSortFilterProxyModel.

Edit:
After taking a look on the QSortFilterProxyModel, I think that QSortFilterProxyModel::filterAcceptsRow() and QSortFilterProxyModel::filterAcceptsColumn() can be methods you want. They are virtual protected so you will need to subclass QSortFilterProxyModel, so take a look at Custom Sort/Filter Model example.

[mholmes]

You're right, that's the way to go; but I'm already using a QSortFilterProxyModel to enable the user to filter the QStringListModel content based on regular expressions. Can you chain together multiple QSortFilterProxyModels (i.e., originalSource->QSortFilterProxyModel to produce item list->QSortFilterProxyModel to allow user filtering)?

Cheers,
Martin

[mholmes]

I've done this, but I'm encountering a problem. My core model is a DomModel object, taken directly from the SimpleDomModel example. That works well with the tree view. Then I'm using my own QSortFilterProxyModel descendant to filter the output, like this:

bool HcmcXmlIdFilter::filterAcceptsRow ( int source_row, const QModelIndex &source_parent ) const{
DomItem *parentItem;

if (source_parent.isValid()){
parentItem = static_cast<DomItem*>(source_parent.internalPointer());
DomItem *childItem = parentItem->child(source_row);
if (childItem){
QDomNode n = childItem->node();
if (n.isElement()){
if (n.toElement().hasAttribute("xml:id")){
return true;
}
}
}
}
return false;
}

However, no content is showing up in the QListView. Even when I set that function to return true by default, only the top level elements show up in the list; child elements in the tree do not seem to be processed. Any suggestions as to what I'm doing wrong?

Cheers,
Martin