lib/volt/models/associations.rb
module Volt
module Associations
module ClassMethods
def belongs_to(method_name, options = {})
collection ||= options.fetch(:collection, method_name).pluralize
foreign_key ||= options.fetch(:foreign_key, :id)
local_key ||= options.fetch(:local_key, "#{method_name}_id")
# Add a field for the association_id
field(local_key)
# getter
define_method(method_name) do
association_with_root_model('belongs_to') do |root|
# Lookup the associated model id
lookup_key = get(local_key)
# Return a promise for the belongs_to
root.get(collection).where(foreign_key => lookup_key).first
end
end
define_method(:"#{method_name}=") do |obj|
id = obj.is_a?(Fixnum) ? obj : obj.id
# Assign the current model's something_id to the object's id
set(local_key, id)
end
end
def has_many(method_name, options = {})
collection ||= options.fetch(:collection, method_name).pluralize
# Use the underscored current class name as the something_id.
foreign_key ||= options.fetch(:foreign_key, "#{to_s.underscore.singularize}_id")
local_key ||= options.fetch(:local_key, :id)
define_method(method_name) do
lookup_key = get(local_key)
array_model = root.get(collection).where(foreign_key => lookup_key)
# Since we are coming off of the root collection, we need to setup
# the right parent and path.
new_path = array_model.options[:path]
# Assign path and parent
array_model.path = self.path + new_path
array_model.parent = self
array_model
end
end
# has_one creates a method on the Volt::Model that returns a promise
# to get the associated model.
def has_one(method_name)
if method_name.plural?
raise NameError, "has_one takes a singluar association name"
end
define_method(method_name) do
association_with_root_model('has_one') do |root|
key = self.class.to_s.underscore + '_id'
root.send(method_name.pluralize).where(key => id).first
end
end
end
end
def self.included(base)
base.send :extend, ClassMethods
end
private
# Currently the has_many and belongs_to associations only work on the store collection,
# this method checks to make sure we are on store and returns the root reference to it.
def association_with_root_model(method_name)
persistor = self.persistor || (respond_to?(:save_to) && save_to && save_to.persistor)
# Check if we are on the store collection
if persistor.is_a?(Volt::Persistors::ModelStore) ||
persistor.is_a?(Volt::Persistors::Page)
# Get the root node
root = persistor.try(:root_model)
# Yield to the block passing in the root node
yield(root)
else
# raise an error about the method not being supported on this collection
fail "#{method_name} currently only works on the store and page collection (support for other collections coming soon)"
end
end
end
end