CODEWITHSUNDEEP
ruby-on-rails
Spyros
Spyros

Reputation: 48626

Rails : How to Arrange the models?

I'm having some trouble arranging my models in an efficient way. Thing of these models :

City
Building
CityBuilding
WoodProduction

Now, of course, a city has many buildings through city_buildings. A city building has some basic attributes like the population living there. However, there are 2 buildings that need to hold more information, like the amount of wood produced, if we are talking about a sawmill.

So, in this example, the sawmill, i would want to be able to do something like :

current_city.wood_production.amount

And get the amount of wood, provided that a city has one wood_production association. Everything fine till this point.

But, wood_production also needs to store a rate at which the wood is produced. This rate is produced by a formula, that needs information about the level of the sawmill building (found in city_buildings).

I have made it work by using a nested association in wood_production like :

has_many :city_buildings, :through => :city

So, now i can execute something like :

c = City.first
w = c.wood_production
w.city_buildings.where(:building_id => ...).level

Which although it works, if feels very unnatural and i'm kinda convinced that there is a much better way of achieving this.

Anything to suggest please :) ?

EDIT : I feel that scope may be a part of a nice solution, like specifying a scope for the sawmill building, maybe someone has thought of something in more detail, i'm kinda processing that idea now.

Upvotes: 1

Views: 52

Answers (1)

Thong Kuah
Thong Kuah

Reputation: 3283

right so you have the through association correct. If the building_id of the sawmill is fixed then you can add another association 

has_many :sawmills, :through => :city, :source => :city_buildings, :conditions => {:building_id => SAWMILL_BUILDING_ID}

w.sawmills.first.level

edit: has_one :through to a has_many would not work

Upvotes: 1

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