Qt Node Editor custom logic data implementation (QGraphicsScene-based)

[hydexon]

Hello, i'm quite new on programming with Qt, i was recently find this: "Qt NodesEditor":http://algoholic.eu/qnodeseditor-qt-nodesports-based-data-processing-flow-editor/
which was sucessfully ported to Qt5, is using the Qt GraphicsScene framework. their code structure i'm find too simple, save and loads diagrams using QDataStream seems to fit. But also i desire how store custom logic data in the blocks, i tried everything, but only stores data from a single block (using a simple class) and need how to track the blocks connected against them and generate an final sample script code (i.e Lua) the author/porter says:

bq. QNodesEditor supports saving and loading of node diagrams. Again – all data are saved as-is (names, connections, positions) without any introspection. It’s up to you to interpret the graphical schematic, attach extra data to it, etc. Blocks and connections are saved in the same order as they’re placed in the QGraphicsScene, so it seems natural to reference them by index when saving your application-specific data.

Someone can give me an approach or idea (i don't ask for code, but i appreciate that :) ) to archieve this?, thanks you.