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module ActiveRecord
module Associations
# 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.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 CollectionProxy < Relation
delegate :target, :load_target, :loaded?, :to => :@association
##
# :method: select
#
# :call-seq:
# select(select = nil)
# select(&block)
#
# Works in two ways.
#
# *First:* Specify a subset of fields to be selected from the result set.
#
# class Person < ActiveRecord::Base
# has_many :pets
# end
#
# person.pets
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# person.pets.select(:name)
# # => [
# # #<Pet id: nil, name: "Fancy-Fancy">,
# # #<Pet id: nil, name: "Spook">,
# # #<Pet id: nil, name: "Choo-Choo">
# # ]
#
# person.pets.select([:id, :name])
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy">,
# # #<Pet id: 2, name: "Spook">,
# # #<Pet id: 3, name: "Choo-Choo">
# # ]
#
# Be careful because this also means you’re initializing a model
# object with only the fields that you’ve selected. If you attempt
# to access a field that is not in the initialized record you’ll
# receive:
#
# person.pets.select(:name).first.person_id
# # => ActiveModel::MissingAttributeError: missing attribute: person_id
#
# *Second:* You can pass a block so it can be used just like Array#select.
# This build an array of objects from the database for the scope,
# converting them into an array and iterating through them using
# Array#select.
#
# person.pets.select { |pet| pet.name =~ /oo/ }
# # => [
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# person.pets.select(:name) { |pet| pet.name =~ /oo/ }
##
# :method: find
#
# :call-seq:
# find(*args, &block)
#
# Finds an object in the collection responding to the +id+. Uses the same
# rules as +ActiveRecord::Base.find+. Returns +ActiveRecord::RecordNotFound++
# error if the object can not be found.
#
# class Person < ActiveRecord::Base
# has_many :pets
# end
#
# person.pets
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# person.pets.find(1) # => #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>
# person.pets.find(4) # => ActiveRecord::RecordNotFound: Couldn't find Pet with id=4
#
# person.pets.find(2) { |pet| pet.name.downcase! }
# # => #<Pet id: 2, name: "fancy-fancy", person_id: 1>
#
# person.pets.find(2, 3)
# # => [
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
##
# :method: first
#
# Returns the first record, or the first +n+ records, from the collection.
# If the collection is empty, the first form returns +nil+, and the second
# form returns an empty array.
#
# class Person < ActiveRecord::Base
# has_many :pets
# end
#
# person.pets
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# person.pets.first # => #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>
#
# person.pets.first(2)
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# # #<Pet id: 2, name: "Spook", person_id: 1>
# # ]
#
# another_person_without.pets # => []
# another_person_without.pets.first # => nil
# another_person_without.pets.first(3) # => []
##
# :method: last
#
# Returns the last record, or the last +n+ records, from the collection.
# If the collection is empty, the first form returns +nil+, and the second
# form returns an empty array.
#
# class Person < ActiveRecord::Base
# has_many :pets
# end
#
# person.pets
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# person.pets.last # => #<Pet id: 3, name: "Choo-Choo", person_id: 1>
#
# person.pets.last(2)
# # => [
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# another_person_without.pets # => []
# another_person_without.pets.last # => nil
# another_person_without.pets.last(3) # => []
##
# :method: build
#
# :call-seq:
# build(attributes = {}, options = {}, &block)
#
# Returns a new object of the collection type that has been instantiated
# with +attributes+ and linked to this object, but have not yet been saved.
# You can pass an array of attributes hashes, this will return an array
# with the new objects.
#
# class Person
# has_many :pets
# end
#
# person.pets.build
# # => #<Pet id: nil, name: nil, person_id: 1>
#
# person.pets.build(name: 'Fancy-Fancy')
# # => #<Pet id: nil, name: "Fancy-Fancy", person_id: 1>
#
# person.pets.build([{name: 'Spook'}, {name: 'Choo-Choo'}, {name: 'Brain'}])
# # => [
# # #<Pet id: nil, name: "Spook", person_id: 1>,
# # #<Pet id: nil, name: "Choo-Choo", person_id: 1>,
# # #<Pet id: nil, name: "Brain", person_id: 1>
# # ]
#
# person.pets.size # => 5 # size of the collection
# person.pets.count # => 0 # count from database
##
# :method: create
#
# :call-seq:
# create(attributes = {}, options = {}, &block)
#
# Returns a new object of the collection type that has been instantiated with
# attributes, linked to this object and that has already been saved (if it
# passed the validations).
#
# class Person
# has_many :pets
# end
#
# person.pets.create(name: 'Fancy-Fancy')
# # => #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>
#
# person.pets.create([{name: 'Spook'}, {name: 'Choo-Choo'}])
# # => [
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# person.pets.size # => 3
# person.pets.count # => 3
#
# person.pets.find(1, 2, 3)
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
##
# :method: concat
#
# :call-seq:
# concat(*records)
#
# Add one or more records to the collection by setting their foreign keys
# to the association's primary key. Since << flattens its argument list and
# inserts each record, +push+ and +concat+ behave identically. Returns +self+
# so method calls may be chained.
#
# class Person < ActiveRecord::Base
# pets :has_many
# end
#
# person.pets.size # => 0
# person.pets.concat(Pet.new(name: 'Fancy-Fancy'))
# person.pets.concat(Pet.new(name: 'Spook'), Pet.new(name: 'Choo-Choo'))
# person.pets.size # => 3
#
# person.id # => 1
# person.pets
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# person.pets.concat([Pet.new(name: 'Brain'), Pet.new(name: 'Benny')])
# person.pets.size # => 5
##
# :method: replace
#
# :call-seq:
# replace(other_array)
#
# Replace this collection with +other_array+. This will perform a diff
# and delete/add only records that have changed.
#
# class Person < ActiveRecord::Base
# has_many :pets
# end
#
# person.pets
# # => [#<Pet id: 1, name: "Gorby", group: "cats", person_id: 1>]
#
# other_pets = [Pet.new(name: 'Puff', group: 'celebrities']
#
# person.pets.replace(other_pets)
#
# person.pets
# # => [#<Pet id: 2, name: "Puff", group: "celebrities", person_id: 1>]
#
# If the supplied array has an incorrect association type, it raises
# an <tt>ActiveRecord::AssociationTypeMismatch</tt> error:
#
# person.pets.replace(["doo", "ggie", "gaga"])
# # => ActiveRecord::AssociationTypeMismatch: Pet expected, got String
##
# :method: delete_all
#
# Deletes all the records from the collection. For +has_many+ it will do the
# deletion according to the strategy specified by the <tt>:dependent</tt>
# option. Returns an array with the deleted records.
#
# If no <tt>:dependent</tt> option is given, then it will follow the
# default strategy. The default strategy is <tt>:nullify</tt>. This
# sets the foreign keys to <tt>NULL</tt>. For, +has_many+ <tt>:through</tt>,
# the default strategy is +delete_all+.
#
# class Person < ActiveRecord::Base
# has_many :pets # dependent: :nullify option by default
# end
#
# person.pets.size # => 3
# person.pets
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# person.pets.delete_all
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# person.pets.size # => 0
# person.pets # => []
#
# Pet.find(1, 2, 3)
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: nil>,
# # #<Pet id: 2, name: "Spook", person_id: nil>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: nil>
# # ]
#
# If it is set to <tt>:destroy</tt> all the objects from the collection
# are removed by calling their +destroy+ method. See +destroy+ for more
# information.
#
# class Person < ActiveRecord::Base
# has_many :pets, dependent: :destroy
# end
#
# person.pets.size # => 3
# person.pets
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# person.pets.delete_all
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# Pet.find(1, 2, 3)
# # => ActiveRecord::RecordNotFound
#
# If it is set to <tt>:delete_all</tt>, all the objects are deleted
# *without* calling their +destroy+ method.
#
# class Person < ActiveRecord::Base
# has_many :pets, dependent: :delete_all
# end
#
# person.pets.size # => 3
# person.pets
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# person.pets.delete_all
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# Pet.find(1, 2, 3)
# # => ActiveRecord::RecordNotFound
##
# :method: destroy_all
#
# Deletes the records of the collection directly from the database.
# This will _always_ remove the records ignoring the +:dependent+
# option.
#
# class Person < ActiveRecord::Base
# has_many :pets
# end
#
# person.pets.size # => 3
# person.pets
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# person.pets.destroy_all
#
# person.pets.size # => 0
# person.pets # => []
#
# Pet.find(1) # => Couldn't find Pet with id=1
##
# :method: destroy
#
# :call-seq:
# destroy(*records)
#
# Destroy the +records+ supplied and remove them from the collection.
# This method will _always_ remove record from the database ignoring
# the +:dependent+ option. Returns an array with the removed records.
#
# class Person < ActiveRecord::Base
# has_many :pets
# end
#
# person.pets.size # => 3
# person.pets
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# person.pets.destroy(Pet.find(1))
# # => [#<Pet id: 1, name: "Fancy-Fancy", person_id: 1>]
#
# person.pets.size # => 2
# person.pets
# # => [
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# person.pets.destroy(Pet.find(2), Pet.find(3))
# # => [
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
#
# person.pets.size # => 0
# person.pets # => []
#
# Pet.find(1, 2, 3) # => ActiveRecord::RecordNotFound: Couldn't find all Pets with IDs (1, 2, 3)
#
# You can pass +Fixnum+ or +String+ values, it finds the records
# responding to the +id+ and then deletes them from the database.
#
# person.pets.size # => 3
# person.pets
# # => [
# # #<Pet id: 4, name: "Benny", person_id: 1>,
# # #<Pet id: 5, name: "Brain", person_id: 1>,
# # #<Pet id: 6, name: "Boss", person_id: 1>
# # ]
#
# person.pets.destroy("4")
# # => #<Pet id: 4, name: "Benny", person_id: 1>
#
# person.pets.size # => 2
# person.pets
# # => [
# # #<Pet id: 5, name: "Brain", person_id: 1>,
# # #<Pet id: 6, name: "Boss", person_id: 1>
# # ]
#
# person.pets.destroy(5, 6)
# # => [
# # #<Pet id: 5, name: "Brain", person_id: 1>,
# # #<Pet id: 6, name: "Boss", person_id: 1>
# # ]
#
# person.pets.size # => 0
# person.pets # => []
#
# Pet.find(4, 5, 6) # => ActiveRecord::RecordNotFound: Couldn't find all Pets with IDs (4, 5, 6)
##
# :method: empty?
#
# Returns +true+ if the collection is empty.
#
# class Person < ActiveRecord::Base
# has_many :pets
# end
#
# person.pets.count # => 1
# person.pets.empty? # => false
#
# person.pets.delete_all
#
# person.pets.count # => 0
# person.pets.empty? # => true
##
# :method: any?
#
# :call-seq:
# any?
# any?{|item| block}
#
# Returns +true+ if the collection is not empty.
#
# class Person < ActiveRecord::Base
# has_many :pets
# end
#
# person.pets.count # => 0
# person.pets.any? # => false
#
# person.pets << Pet.new(name: 'Snoop')
# person.pets.count # => 0
# person.pets.any? # => true
#
# You can also pass a block to define criteria. The behaviour
# is the same, it returns true if the collection based on the
# criteria is not empty.
#
# person.pets
# # => [#<Pet name: "Snoop", group: "dogs">]
#
# person.pets.any? do |pet|
# pet.group == 'cats'
# end
# # => false
#
# person.pets.any? do |pet|
# pet.group == 'dogs'
# end
# # => true
##
# :method: many?
#
# :call-seq:
# many?
# many?{|item| block}
#
# Returns true if the collection has more than one record.
# Equivalent to <tt>collection.size > 1</tt>.
#
# class Person < ActiveRecord::Base
# has_many :pets
# end
#
# person.pets.count #=> 1
# person.pets.many? #=> false
#
# person.pets << Pet.new(name: 'Snoopy')
# person.pets.count #=> 2
# person.pets.many? #=> true
#
# You can also pass a block to define criteria. The
# behaviour is the same, it returns true if the collection
# based on the criteria has more than one record.
#
# person.pets
# # => [
# # #<Pet name: "Gorby", group: "cats">,
# # #<Pet name: "Puff", group: "cats">,
# # #<Pet name: "Snoop", group: "dogs">
# # ]
#
# person.pets.many? do |pet|
# pet.group == 'dogs'
# end
# # => false
#
# person.pets.many? do |pet|
# pet.group == 'cats'
# end
# # => true
##
# :method: include?
#
# :call-seq:
# include?(record)
#
# Returns +true+ if the given object is present in the collection.
#
# class Person < ActiveRecord::Base
# has_many :pets
# end
#
# person.pets # => [#<Pet id: 20, name: "Snoop">]
#
# person.pets.include?(Pet.find(20)) # => true
# person.pets.include?(Pet.find(21)) # => false
delegate :select, :find, :first, :last,
:build, :create, :create!,
:concat, :replace, :delete_all, :destroy_all, :delete, :destroy, :uniq,
:sum, :count, :size, :length, :empty?,
:any?, :many?, :include?,
:to => :@association
def initialize(association)
@association = association
super association.klass, association.klass.arel_table
merge! association.scoped
end
alias_method :new, :build
def proxy_association
@association
end
# We don't want this object to be put on the scoping stack, because
# that could create an infinite loop where we call an @association
# method, which gets the current scope, which is this object, which
# delegates to @association, and so on.
def scoping
@association.scoped.scoping { yield }
end
def spawn
scoped
end
def scoped(options = nil)
association = @association
super.extending! do
define_method(:proxy_association) { association }
end
end
def ==(other)
load_target == other
end
def to_ary
load_target.dup
end
alias_method :to_a, :to_ary
# Adds one or more +records+ to the collection by setting their foreign keys
# to the association‘s primary key. Returns +self+, so several appends may be
# chained together.
#
# class Person < ActiveRecord::Base
# has_many :pets
# end
#
# person.pets.size # => 0
# person.pets << Pet.new(name: 'Fancy-Fancy')
# person.pets << [Pet.new(name: 'Spook'), Pet.new(name: 'Choo-Choo')]
# person.pets.size # => 3
#
# person.id # => 1
# person.pets
# # => [
# # #<Pet id: 1, name: "Fancy-Fancy", person_id: 1>,
# # #<Pet id: 2, name: "Spook", person_id: 1>,
# # #<Pet id: 3, name: "Choo-Choo", person_id: 1>
# # ]
def <<(*records)
proxy_association.concat(records) && self
end
alias_method :push, :<<
# Equivalent to +delete_all+. The difference is that returns +self+, instead
# of an array with the deleted objects, so methods can be chained. See
# +delete_all+ for more information.
def clear
delete_all
self
end
# Reloads the collection from the database. Returns +self+.
# Equivalent to <tt>collection(true)</tt>.
#
# class Person < ActiveRecord::Base
# has_many :pets
# end
#
# person.pets # fetches pets from the database
# # => [#<Pet id: 1, name: "Snoop", group: "dogs", person_id: 1>]
#
# person.pets # uses the pets cache
# # => [#<Pet id: 1, name: "Snoop", group: "dogs", person_id: 1>]
#
# person.pets.reload # fetches pets from the database
# # => [#<Pet id: 1, name: "Snoop", group: "dogs", person_id: 1>]
#
# person.pets(true)  # fetches pets from the database
# # => [#<Pet id: 1, name: "Snoop", group: "dogs", person_id: 1>]
def reload
proxy_association.reload
self
end
end
end
end
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