Polymorphic, STI or other

Question

I am unsure of the best way to approach this scenario and would appreciate some direction. Essentially I have a scenario whereby I need to record assets for an organisation.

There are various types of assets so the attributes differ from type to type however there are a number of fields common to all assets such as:

location
make
model
colour
purchase_date
warranty_period

Similar to: How to design a product table for many kinds of product where each product has many parameters

I had through of creating this as

one-to_many between Organisation and Asset
polymorhpic between Asset and Details

class Organisation < ApplicationRecord
  has_many :assets
end

class Asset < ApplicationRecord
  belongs_to :organisation
  belongs to :detail, polymorphic: true
end

class CarAsset < ApplicationRecord
  has_one :asset, as: :detail
end

class ComputerAsset < ApplicationRecord
  has_one :asset, as: :detail
end

My question is: I wish to create the asset & detail in a single form action so the user after selecting the asset type makes a single form entry for both models.

The user would click a link on the organisation show page:

<%= link_to "New car asset", new_organisation_asset_path(@organisation, query: :new_car_asset) %>

The in my controller I could do something similar to:

class AssetsController < ApplicationController
  def new
    @organisation = Organisation.find(params["organisation_id"])
    @asset  = @organisation.assets.new

    case params[:query]
      when "new_car_asset"
        @details = @asset.car_assets.new
      when "new_computer_asset"
        @details = @asset.computer_assets.new
    end
  end
end

In my view I could also check the value of params[:query] and render the corresponding form partial that relates to the asset type.

Is this going down the correct path or is there a better way to achieve this? It does feel quite clunky.

score 0 · Answer 1 · answered Aug 21 '17 at 09:29

I think it would be maybe better to use has_many :trough, should get more out of it in a long run. Like this:

class Organisation < ApplicationRecord
  has_many :cars, through: assets
  has_many :cumputers, through: assets
  has_many :locations, through: assets
  has_many :purchase_date, through: assets
end

class Asset < ApplicationRecord
  belongs_to :organisation
  belongs_to :cars
  belongs_to :cumputers
  belongs_to any :locations
  belongs_to :purchase_date
end

class Car < ApplicationRecord
  has_one :organisation, through: assets
end

class Cumputer < ApplicationRecord
  has_one :organisation, through: assets
end

class Location < ApplicationRecord
  has_one :organisation, through: assets
end

class Purchase_date < ApplicationRecord
  has_one :organisation, through: assets
end

Then you can create Assets within Organisations_controller and can nest everything in Organisation form with fields_for. Assets model would contain references between Organisation and every single detail model, but everything would be sepperate if you wonna do more with it in views or special fields.

Polymorphic, STI or other

1 Answers1