tjbarker

content copied from Advanced Arel: When ActiveRecord Just Isn't Enough

further information:

• arel_cheatsheet_on_steroids
• Rails test examples
• Arel helpers
• Complex Arel queries

Arel Cheatsheet

tjbarker

# this is a helper method to provide setters for polymorphic relationships in active admin forms
# attribute_name: name that record knows polymorphic relationship as
# actions: the active record actions that should use this setter, defaults to setter being implemented before create and update
def polymorphic_attribute_set(attribute_name, actions: [:before_create, :before_update])
  klass = config.resource_class
  foreign_key = klass.reflect_on_all_associations.find { |ref| ref.name == attribute_name }.association_foreign_key
  setter = lambda do |rec|
    record = ApplicationRecord.identifier_to_record(params[klass.name.snakecase][foreign_key])
    resource.send("#{attribute_name}=", record)
  end

tjbarker

# code set up
class Big < ApplicationRecord
  has_many :littles
end

class Little < ApplicationRecord
  belongs_to :big # foreign_key is the default littles.big_id
end

# in console