In my case i is an int ...

To store additional info for models I use some kind of csv-file.
Each line contains a referenceID to the model and about 30 additional data for each model.
I read those data into struct objects and store those objects in a hashmap using the referenceID as key.
So I can directly access those struct objects for each model. I can even store states like "door is open" during the whole game. So when I leave the room and load the next and then come back later to the same room, the door is still open.