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# This is the parent Association class which defines the variables
# used by all associations.
#
# The hierarchy is defined as follows:
# Association
# - SingularAssociation
# - BelongsToAssociation
# - HasOneAssociation
# - CollectionAssociation
# - HasManyAssociation
# - HasAndBelongsToManyAssociation
module ActiveRecord::Associations::Builder
class Association #:nodoc:
class << self
attr_accessor :extensions
end
self.extensions = []
VALID_OPTIONS = [:class_name, :class, :foreign_key, :validate]
attr_reader :name, :scope, :options
def self.build(model, name, scope, options, &block)
raise ArgumentError, "association names must be a Symbol" unless name.kind_of?(Symbol)
if scope.is_a?(Hash)
options = scope
scope = nil
end
builder = new(name, scope, options, &block)
reflection = builder.build(model)
builder.define_accessors model
builder.define_callbacks model, reflection
builder.define_extensions model
reflection
end
def initialize(name, scope, options)
@name = name
@scope = scope
@options = options
validate_options
if scope && scope.arity == 0
@scope = proc { instance_exec(&scope) }
end
end
def build(model)
ActiveRecord::Reflection.create(macro, name, scope, options, model)
end
def macro
raise NotImplementedError
end
def valid_options
VALID_OPTIONS + Association.extensions.flat_map(&:valid_options)
end
def validate_options
options.assert_valid_keys(valid_options)
end
def define_extensions(model)
end
def define_callbacks(model, reflection)
add_before_destroy_callbacks(model, name) if options[:dependent]
Association.extensions.each do |extension|
extension.build model, reflection
end
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(model)
mixin = model.generated_feature_methods
define_readers(mixin)
define_writers(mixin)
end
def define_readers(mixin)
mixin.class_eval <<-CODE, __FILE__, __LINE__ + 1
def #{name}(*args)
association(:#{name}).reader(*args)
end
CODE
end
def define_writers(mixin)
mixin.class_eval <<-CODE, __FILE__, __LINE__ + 1
def #{name}=(value)
association(:#{name}).writer(value)
end
CODE
end
def valid_dependent_options
raise NotImplementedError
end
private
def add_before_destroy_callbacks(model, name)
unless valid_dependent_options.include? options[:dependent]
raise ArgumentError, "The :dependent option must be one of #{valid_dependent_options}, but is :#{options[:dependent]}"
end
model.before_destroy lambda { |o| o.association(name).handle_dependency }
end
end
end
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