habanero | client for Crossref search API | REST library

Bear with me, it's a tricky question and what resources I've found around don't really help me resolve my problem.

I'm trying to build a real estate-oriented app on Kotlin. It must show at some point a RecyclerView with multiple object classes (say: houses, flats, plots, buildings, etc.)

I've seen multiple examples of RVs designed to accept multiple classes, but I'm struggling to put together a DB and the intermediary classes translating between tables and POJOs.

So far I've figured the following:

• I must have a Properties table that stores the unique ID for every object, along with another identifier for its type and a series of values common to every property (say, address, price, etc.)
• I must have a table for each entity type that can be independently listed as a real estate item (say, a house, a flat, a plot of land, a building, what have you). Each row on those tables will have a primary foreign key referencing its equivalent on the Properties table.

Now for the unexpected habanero. I decided to start sketching out my project on the basis of the RecyclerView Kotlin codelabs Google put together for newbies like me. Therein data is retrieved from the DB in this fashion:

this.plots = Transformations.map(database.RealtorDao.getPlots()) { it.asDomainModel() }

This works smoothly enough when the objects on the list the DB spits at you are all of one single kind, but what happens if you need them to be of different classes so that the adapter can tell them apart?

Or the only way around is just to build a gigantic table with about a hundred columns that will have nulls everywhere, and sort out objects ONLY AFTER they've been parsed in the previously described fashion?

I am able to select the image from the directory and store in the specified cell, but I can't work out how to get it to save to the Database. I hit enter or tab and the image just goes away.

Here is the delegate I am currently using

I have a JSON Structure something like:

I am calling the Habanero API which is a front end to CrossRef. With this code:

I have a problem where I have two types of Topping classes, a normal "Topping" class, and one which inherits from Topping and adds a SpiceLevel, Called "SpicyTopping".

My problem is that whenever I construct a SpicyTopping object, the SpiceLevel is set to 0 and I have to manually set it after constructing the object