Smart collection or automated collection is a concept putted forward by Shopify. Those collections automatically include or exclude items according to conditions defined by users.
This plugin allows you to define a collection as an union of multiple scopes; meanwhile preloading and inverse query are possible.
Add gem 'smart_collection' to your Gemfile and bundle.
# create collection table
class CreateCollections < ActiveRecord::Migration[5.0]
def change
create_table :collections do |t|
t.datetime :cache_expires_at
t.timestamps
end
end
end
# create cache table
class CreateSmartCollectionCachedItems < ActiveRecord::Migration[5.0]
def change
create_table :smart_collection_cached_items do |t|
t.integer :collection_id
t.integer :item_id
end
end
end
# define model
class Collection < ActiveRecord::Base
include SmartCollection::Mixin.new(
item_association: :products,
item_class_name: 'Product',
# scopes option can be a method name / proc that returns an array of scopes
scopes: -> (collection) {
[Product.all]
},
# the table :smart_collection_cached_items is used when cache_table_name setted :default
cache_table_name: :default,
# cache_expires_in can be a duration or a method name / proc that returns a duration
cache_expires_in: 1.hour,
# defines an inverse association on the item class
inverse_association: :collections
)
end# create a collection:
collection = Collection.create
# fetch products by defined scope
collection.products # => all products will be returned
collection.products.where(in_stock: true).order(id: :desc) #=> association returns a scope# use includes or preload to avoid n+1 queries
Collection.where(id: [1, 2]).preload(products: :properties)bundle exec rake