QModelIndex::parent question

[wysota]

Derive both Apartment and Occupant from the common base class and either use dynamic_cast or implement virtual methods isOccupant() and isApartment() in the base class and reimplement them in the subclasses properly so that you can determine the type of the object by calling one of these.

[QPlace]

I was afraid that would be the answer, hoping that I missed something in the documentation.

So, one has to rely on RTTI to construct a model for a tree view.. Sad.

I have another, kind of a follow-up question.

I am under the assumption (did not actually test it myself) that all view models are "virtual", in a sense that the Qt framework will not ask model for a complete range of QModelIndexes.

Suppose I have 10^6 Occupants in the city and my QTreeView has only two visible Apartments with 5 occupants total. Will my model be a subject to 10^6 or more calls to ::index and :: parent methods? If yes - what is the Qt-way to implement virtual models?

[wysota]

So, one has to rely on RTTI to construct a model for a tree view.. Sad.

Not really. But with your current design you have to either use RTTI or virtual methods.

I am under the assumption (did not actually test it myself) that all view models are "virtual", in a sense that the Qt framework will not ask model for a complete range of QModelIndexes.

Suppose I have 10^6 Occupants in the city and my QTreeView has only two visible Apartments with 5 occupants total. Will my model be a subject to 10^6 or more calls to ::index and :: parent methods? If yes - what is the Qt-way to implement virtual models?

The view will only ask for the indexes it currently needs. Just remember it might need them all if you, for example, force the width of a column to be resized to the size of its contents.

[QPlace]

Thank you for the help and clarifications.