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|
module ActiveRecord
module Associations
# This is the root class of all association proxies:
#
# AssociationProxy
# BelongsToAssociation
# HasOneAssociation
# BelongsToPolymorphicAssociation
# AssociationCollection
# HasManyAssociation
# HasAndBelongsToManyAssociation
# HasManyThroughAssociation
# HasOneThroughAssociation
#
# Association proxies in Active Record are middlemen between the object that
# holds the association, known as the <tt>@owner</tt>, and the actual associated
# object, known as the <tt>@target</tt>. The kind of association any proxy is
# about is available in <tt>@reflection</tt>. That's an instance of the class
# ActiveRecord::Reflection::AssociationReflection.
#
# For example, given
#
# class Blog < ActiveRecord::Base
# has_many :posts
# end
#
# blog = Blog.find(:first)
#
# the association proxy in <tt>blog.posts</tt> has the object in +blog+ as
# <tt>@owner</tt>, the collection of its posts as <tt>@target</tt>, and
# the <tt>@reflection</tt> object represents a <tt>:has_many</tt> macro.
#
# This class has most of the basic instance methods removed, and delegates
# unknown methods to <tt>@target</tt> via <tt>method_missing</tt>. As a
# corner case, it even removes the +class+ method and that's why you get
#
# blog.posts.class # => Array
#
# though the object behind <tt>blog.posts</tt> is not an Array, but an
# ActiveRecord::Associations::HasManyAssociation.
#
# The <tt>@target</tt> object is not loaded until needed. For example,
#
# blog.posts.count
#
# is computed directly through SQL and does not trigger by itself the
# instantiation of the actual post records.
class AssociationProxy #:nodoc:
alias_method :proxy_respond_to?, :respond_to?
alias_method :proxy_extend, :extend
delegate :to_param, :to => :proxy_target
instance_methods.each { |m| undef_method m unless m =~ /(^__|^nil\?$|^send$|proxy_)/ }
def initialize(owner, reflection)
@owner, @reflection = owner, reflection
Array(reflection.options[:extend]).each { |ext| proxy_extend(ext) }
reset
end
def proxy_owner
@owner
end
def proxy_reflection
@reflection
end
def proxy_target
@target
end
def respond_to?(symbol, include_priv = false)
proxy_respond_to?(symbol, include_priv) || (load_target && @target.respond_to?(symbol, include_priv))
end
# Explicitly proxy === because the instance method removal above
# doesn't catch it.
def ===(other)
load_target
other === @target
end
def aliased_table_name
@reflection.klass.table_name
end
def conditions
@conditions ||= interpolate_sql(sanitize_sql(@reflection.options[:conditions])) if @reflection.options[:conditions]
end
alias :sql_conditions :conditions
def reset
@loaded = false
@target = nil
end
def reload
reset
load_target
self unless @target.nil?
end
def loaded?
@loaded
end
def loaded
@loaded = true
end
def target
@target
end
def target=(target)
@target = target
loaded
end
def inspect
reload unless loaded?
@target.inspect
end
protected
def dependent?
@reflection.options[:dependent]
end
def quoted_record_ids(records)
records.map { |record| record.quoted_id }.join(',')
end
def interpolate_sql_options!(options, *keys)
keys.each { |key| options[key] &&= interpolate_sql(options[key]) }
end
def interpolate_sql(sql, record = nil)
@owner.send(:interpolate_sql, sql, record)
end
def sanitize_sql(sql)
@reflection.klass.send(:sanitize_sql, sql)
end
def set_belongs_to_association_for(record)
if @reflection.options[:as]
record["#{@reflection.options[:as]}_id"] = @owner.id unless @owner.new_record?
record["#{@reflection.options[:as]}_type"] = @owner.class.base_class.name.to_s
else
record[@reflection.primary_key_name] = @owner.id unless @owner.new_record?
end
end
def merge_options_from_reflection!(options)
options.reverse_merge!(
:group => @reflection.options[:group],
:limit => @reflection.options[:limit],
:offset => @reflection.options[:offset],
:joins => @reflection.options[:joins],
:include => @reflection.options[:include],
:select => @reflection.options[:select],
:readonly => @reflection.options[:readonly]
)
end
def with_scope(*args, &block)
@reflection.klass.send :with_scope, *args, &block
end
private
def method_missing(method, *args)
if load_target
if block_given?
@target.send(method, *args) { |*block_args| yield(*block_args) }
else
@target.send(method, *args)
end
end
end
def load_target
return nil unless defined?(@loaded)
if !loaded? and (!@owner.new_record? || foreign_key_present)
@target = find_target
end
@loaded = true
@target
rescue ActiveRecord::RecordNotFound
reset
end
# Can be overwritten by associations that might have the foreign key available for an association without
# having the object itself (and still being a new record). Currently, only belongs_to presents this scenario.
def foreign_key_present
false
end
def raise_on_type_mismatch(record)
unless record.is_a?(@reflection.klass)
raise ActiveRecord::AssociationTypeMismatch, "#{@reflection.klass} expected, got #{record.class}"
end
end
# Array#flatten has problems with recursive arrays. Going one level deeper solves the majority of the problems.
def flatten_deeper(array)
array.collect { |element| element.respond_to?(:flatten) ? element.flatten : element }.flatten
end
end
end
end
|
