Defining Models with Relations
We'll cover the following...
Redux-ORM allows you to define relations between various model types, using standard database concepts. This is done by adding a fields entry on a Model class type itself, and using the relation operators provided by Redux-ORM. Also, as described previously, when a Model instance is created Redux-ORM will generate getter properties for all fields in the actual data object, as well as all of the relational fields.
With those ideas in mind, we’re almost ready to define our next couple Model types, but first we need to review a bit more information about the ideas we’re trying to represent. In Battletech, there are many different Battlemech designs. Each design has different statistics: weight, speed, armor, weapons, and so on. There may also be different variations on the same design, which would share the same basic characteristics (usually weight and speed), but maybe have some differences in weapons and armor. There can be many different individual mechs of the same design. Here’s some examples of different Battlemech design variants to give you the idea:
- Stinger STG-3R: 20 tons; 6/9/6 movement points (walk/run/jump); 48 armor points; 1 Medium Laser and 2 Machine Guns
- Stinger STG-3G: 20 tons; 6/9/6 movement points; 69 armor points; 2 Medium Lasers
- Warhammer WHM-6R: 70 tons; 4/6 movement points; 160 armor points; 2 PPCs, 2 Medium Lasers, 2 Small Lasers, 1 SRM-6 launcher
- Warhammer WHM-6D: 70 tons; 4/6 movement points; 217 armor points; 2 PPCs, 2 Medium Lasers, 2 Small Lasers
As a real-life comparison, the F-15 Eagle has several variants: the F-15C is made for air-to-air combat, the F-15D is a training version, the F-15E is intended for ground attacks, and hundreds of individual F-15s have been manufactured.
For our data modeling, we’re going to create two more Model classes. We’re going to need to store information on different Battlemech designs, and we also need to track individual mechs. Rather than copy all the attributes of a design into each individual Mech entry, we can just store the design once, and add a relation between the individual Mech and its design entry. Meanwhile, since Pilots are going to be assigned to Mechs, we would also want to be able to relate Pilots ...