QtCS25 - QGenericItemModel

Session Summary

General solution to expose C++ data to QtQuick.

Based on QAbstractItemModel, uses a templated constructor taking a Range by a universal ref (see docs)

Session Owners

Presenter: Volker

Notes: Ivan

Notes

Some live examples:

• Passing data by const & non-const values, references or ptrs.
  • Q: Should we forbid passing by value?
  • Passing const data by value -> data in the model is still const, even though it's copied internally. Confusing for C++ developers.
• Using different input types
  • vector
  • Json array
  • list of tuples -> representing multi-column data
  • QMetaEnumerator
  • actual C++20 ranges
• Unbounded ranges
  • Q: How to handle that nicely? Do we need fetchMore() for that?
• QList<QList<Gadget>> -> table.
• MultiColumn vs SingleColumn:
  • vector of ptrs to MultiColumn -> table
  • vector of ptrs to SingleColumn -> list

More questions:

• What if we store pointers? Who takes the ownership when we create an instance from QML?
  • That's the why we need second c-tor that takes the Protocol type - see docs for more details.
• How to modify the data that we handled to the model (by ref or ptr) without using the QAIM API?
  • Various approaches are possible - TBD.