An ActiveRecord plugin that allows you to create customized association.
Add gem 'associationist' to your Gemfile and bundle.
Define a customized association:
class Product < ApplicationRecord
include Associationist::Mixin.new(
name: :stock,
# You can choose to implement one or many of [loader, preloader, scope].
# loader is for singly association loading. The return value can be of any type. n+1 query cannot be avoided by this strategy.
loader: -> product {
100
},
# preloader is for batch loading. It prevents n+1 query when using with includes and preload.
# When preloader is defined, definition of loader is optional.
preloader: -> products {
products.map{|product| [product, 100]}.to_h
},
# scope defines the scope that will be returned when reading association.
# Only one of [scope, loader] should be defined.
scope: -> product {
Stock.where(product_id: product)
},
# Available options: [:singular, :collection]. Use when scope option is defined, to determine the association is singluar or collection.
type: :singular
)
end
Product.all.includes(:stock).map(&:stock) # => [100, ...]
# use Associationist.preload to trigger a preloading for collections that are already load
Associationist.preload(products, :stock)bundle rake