What exactly changed when QStandardItemModel itemChanged is signaled
qt, user-interface
Solution
In general, `QStandardItemModel` is for very simple data modeling. If you want to get into more advanced things like you desribe, you should look into subclassing `QAbstractItemModel` or one of it's abstract derivatives: Model/View classes
It may seem like a lot of work, but use the examples and refernce guides: Model/View programming, Model subclassing and the rewards will be great.
Problem
There is signal in QStandardItemModel which is emitted when data of an item is changed. Usually we connect a handler for this signal and do all the work in the handler routine. Such handle routine only gets pointer to the item. Using this pointer it is possible to access the data of the item. However, we do not know what exactly has changed... we only have updated value. If item data has several roles I want to be able to get exactly which role (data) has been changed and what was the previous value.