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# This is the parent Association class which defines certain class variables (valid_options) and
# instance variables (model, name, scope, options, reflection) which would be common across all the associations that we known today in Rails..
# Every association need to have the values of these variables set and they are used at multiple places
# The heirarchy is defined as follows:
# Association
# - SingularAssociation
# - BelongsTo
# - HasOne
# - CollectionAssociation
# - HasMany
# - HasAndBelongsToMany
#
# The HasMany :Through association is a special case of HasMany association with the :through option set for it
#
module ActiveRecord::Associations::Builder
class Association #:nodoc:
class << self
attr_accessor :valid_options
end
self.valid_options = [:class_name, :foreign_key, :validate]
attr_reader :model, :name, :scope, :options, :reflection
def self.build(*args, &block)
new(*args, &block).build
end
def initialize(model, name, scope, options)
raise ArgumentError, "association names must be a Symbol" unless name.kind_of?(Symbol)
@model = model
@name = name
if scope.is_a?(Hash)
@scope = nil
@options = scope
else
@scope = scope
@options = options
end
if @scope && @scope.arity == 0
prev_scope = @scope
@scope = proc { instance_exec(&prev_scope) }
end
end
def mixin
@model.generated_feature_methods
end
include Module.new { def build; end }
def build
validate_options
define_accessors
configure_dependency if options[:dependent]
@reflection = model.create_reflection(macro, name, scope, options, model)
super # provides an extension point
@reflection
end
def macro
raise NotImplementedError
end
def valid_options
Association.valid_options
end
def validate_options
options.assert_valid_keys(valid_options)
end
# Defines the setter and getter methods for the association
# class Post < ActiveRecord::Base
# has_many :comments
# end
#
# Post.first.comments and Post.first.comments= methods are defined by this method...
def define_accessors
define_readers
define_writers
end
def define_readers
mixin.class_eval <<-CODE, __FILE__, __LINE__ + 1
def #{name}(*args)
association(:#{name}).reader(*args)
end
CODE
end
def define_writers
mixin.class_eval <<-CODE, __FILE__, __LINE__ + 1
def #{name}=(value)
association(:#{name}).writer(value)
end
CODE
end
def configure_dependency
unless valid_dependent_options.include? options[:dependent]
raise ArgumentError, "The :dependent option must be one of #{valid_dependent_options}, but is :#{options[:dependent]}"
end
if options[:dependent] == :restrict
ActiveSupport::Deprecation.warn(
"The :restrict option is deprecated. Please use :restrict_with_exception instead, which " \
"provides the same functionality."
)
end
mixin.class_eval <<-CODE, __FILE__, __LINE__ + 1
def #{macro}_dependent_for_#{name}
association(:#{name}).handle_dependency
end
CODE
model.before_destroy "#{macro}_dependent_for_#{name}"
end
def valid_dependent_options
raise NotImplementedError
end
end
end
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