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module ActiveRecord
module Associations
# = Active Record Association Collection
#
# CollectionAssociation is an abstract class that provides common stuff to
# ease the implementation of association proxies that represent
# collections. See the class hierarchy in Association.
#
# CollectionAssociation:
# HasManyAssociation => has_many
# HasManyThroughAssociation + ThroughAssociation => has_many :through
#
# CollectionAssociation class provides common methods to the collections
# defined by +has_and_belongs_to_many+, +has_many+ or +has_many+ with
# +:through association+ option.
#
# You need to be careful with assumptions regarding the target: The proxy
# does not fetch records from the database until it needs them, but new
# ones created with +build+ are added to the target. So, the target may be
# non-empty and still lack children waiting to be read from the database.
# If you look directly to the database you cannot assume that's the entire
# collection because new records may have been added to the target, etc.
#
# If you need to work on all current children, new and existing records,
# +load_target+ and the +loaded+ flag are your friends.
class CollectionAssociation < Association #:nodoc:
def initialize(owner, reflection)
super
@proxy = CollectionProxy.create(klass, self)
end
# Implements the reader method, e.g. foo.items for Foo.has_many :items
def reader(force_reload = false)
if force_reload
klass.uncached { reload }
elsif stale_target?
reload
end
@proxy
end
# Implements the writer method, e.g. foo.items= for Foo.has_many :items
def writer(records)
replace(records)
end
# Implements the ids reader method, e.g. foo.item_ids for Foo.has_many :items
def ids_reader
if loaded?
load_target.map do |record|
record.send(reflection.association_primary_key)
end
else
column = "#{reflection.quoted_table_name}.#{reflection.association_primary_key}"
scope.pluck(column)
end
end
# Implements the ids writer method, e.g. foo.item_ids= for Foo.has_many :items
def ids_writer(ids)
pk_column = reflection.primary_key_column
ids = Array(ids).reject { |id| id.blank? }
ids.map! { |i| pk_column.type_cast(i) }
replace(klass.find(ids).index_by { |r| r.id }.values_at(*ids))
end
def reset
super
@target = []
end
def select(*fields)
if block_given?
load_target.select.each { |e| yield e }
else
scope.select(*fields)
end
end
def find(*args)
if block_given?
load_target.find(*args) { |*block_args| yield(*block_args) }
else
if options[:inverse_of] && loaded?
args_flatten = args.flatten
raise RecordNotFound, "Couldn't find #{scope.klass.name} without an ID" if args_flatten.blank?
result = find_by_scan(*args)
result_size = Array(result).size
if !result || result_size != args_flatten.size
scope.raise_record_not_found_exception!(args_flatten, result_size, args_flatten.size)
else
result
end
else
scope.find(*args)
end
end
end
def first(*args)
first_nth_or_last(:first, *args)
end
def second(*args)
first_nth_or_last(:second, *args)
end
def third(*args)
first_nth_or_last(:third, *args)
end
def fourth(*args)
first_nth_or_last(:fourth, *args)
end
def fifth(*args)
first_nth_or_last(:fifth, *args)
end
def forty_two(*args)
first_nth_or_last(:forty_two, *args)
end
def last(*args)
first_nth_or_last(:last, *args)
end
def build(attributes = {}, &block)
if attributes.is_a?(Array)
attributes.collect { |attr| build(attr, &block) }
else
add_to_target(build_record(attributes)) do |record|
yield(record) if block_given?
end
end
end
def create(attributes = {}, &block)
create_record(attributes, &block)
end
def create!(attributes = {}, &block)
create_record(attributes, true, &block)
end
# Add +records+ to this association. Returns +self+ so method calls may
# be chained. Since << flattens its argument list and inserts each record,
# +push+ and +concat+ behave identically.
def concat(*records)
load_target if owner.new_record?
if owner.new_record?
concat_records(records)
else
transaction { concat_records(records) }
end
end
# Starts a transaction in the association class's database connection.
#
# class Author < ActiveRecord::Base
# has_many :books
# end
#
# Author.first.books.transaction do
# # same effect as calling Book.transaction
# end
def transaction(*args)
reflection.klass.transaction(*args) do
yield
end
end
# Removes all records from the association without calling callbacks
# on the associated records. It honors the `:dependent` option. However
# if the `:dependent` value is `:destroy` then in that case the `:delete_all`
# deletion strategy for the association is applied.
#
# You can force a particular deletion strategy by passing a parameter.
#
# Example:
#
# @author.books.delete_all(:nullify)
# @author.books.delete_all(:delete_all)
#
# See delete for more info.
def delete_all(dependent = nil)
if dependent.present? && ![:nullify, :delete_all].include?(dependent)
raise ArgumentError, "Valid values are :nullify or :delete_all"
end
dependent = if dependent.present?
dependent
elsif options[:dependent] == :destroy
:delete_all
else
options[:dependent]
end
delete(:all, dependent: dependent).tap do
reset
loaded!
end
end
# Destroy all the records from this association.
#
# See destroy for more info.
def destroy_all
destroy(load_target).tap do
reset
loaded!
end
end
# Count all records using SQL. Construct options and pass them with
# scope to the target class's +count+.
def count(column_name = nil, count_options = {})
# TODO: Remove count_options argument as soon we remove support to
# activerecord-deprecated_finders.
column_name, count_options = nil, column_name if column_name.is_a?(Hash)
relation = scope
if association_scope.distinct_value
# This is needed because 'SELECT count(DISTINCT *)..' is not valid SQL.
column_name ||= reflection.klass.primary_key
relation = relation.distinct
end
value = relation.count(column_name)
limit = options[:limit]
offset = options[:offset]
if limit || offset
[ [value - offset.to_i, 0].max, limit.to_i ].min
else
value
end
end
# Removes +records+ from this association calling +before_remove+ and
# +after_remove+ callbacks.
#
# This method is abstract in the sense that +delete_records+ has to be
# provided by descendants. Note this method does not imply the records
# are actually removed from the database, that depends precisely on
# +delete_records+. They are in any case removed from the collection.
def delete(*records)
_options = records.extract_options!
dependent = _options[:dependent] || options[:dependent]
if records.first == :all
if loaded? || dependent == :destroy
delete_or_destroy(load_target, dependent)
else
delete_records(:all, dependent)
end
else
records = find(records) if records.any? { |record| record.kind_of?(Fixnum) || record.kind_of?(String) }
delete_or_destroy(records, dependent)
end
end
# Deletes the +records+ and removes them from this association calling
# +before_remove+ , +after_remove+ , +before_destroy+ and +after_destroy+ callbacks.
#
# Note that this method removes records from the database ignoring the
# +:dependent+ option.
def destroy(*records)
records = find(records) if records.any? { |record| record.kind_of?(Fixnum) || record.kind_of?(String) }
delete_or_destroy(records, :destroy)
end
# Returns the size of the collection by executing a SELECT COUNT(*)
# query if the collection hasn't been loaded, and calling
# <tt>collection.size</tt> if it has.
#
# If the collection has been already loaded +size+ and +length+ are
# equivalent. If not and you are going to need the records anyway
# +length+ will take one less query. Otherwise +size+ is more efficient.
#
# This method is abstract in the sense that it relies on
# +count_records+, which is a method descendants have to provide.
def size
if !find_target? || loaded?
if association_scope.distinct_value
target.uniq.size
else
target.size
end
elsif !loaded? && !association_scope.group_values.empty?
load_target.size
elsif !loaded? && !association_scope.distinct_value && target.is_a?(Array)
unsaved_records = target.select { |r| r.new_record? }
unsaved_records.size + count_records
else
count_records
end
end
# Returns the size of the collection calling +size+ on the target.
#
# If the collection has been already loaded +length+ and +size+ are
# equivalent. If not and you are going to need the records anyway this
# method will take one less query. Otherwise +size+ is more efficient.
def length
load_target.size
end
# Returns true if the collection is empty.
#
# If the collection has been loaded
# it is equivalent to <tt>collection.size.zero?</tt>. If the
# collection has not been loaded, it is equivalent to
# <tt>collection.exists?</tt>. If the collection has not already been
# loaded and you are going to fetch the records anyway it is better to
# check <tt>collection.length.zero?</tt>.
def empty?
if loaded?
size.zero?
else
@target.blank? && !scope.exists?
end
end
# Returns true if the collections is not empty.
# Equivalent to +!collection.empty?+.
def any?
if block_given?
load_target.any? { |*block_args| yield(*block_args) }
else
!empty?
end
end
# Returns true if the collection has more than 1 record.
# Equivalent to +collection.size > 1+.
def many?
if block_given?
load_target.many? { |*block_args| yield(*block_args) }
else
size > 1
end
end
def distinct
seen = {}
load_target.find_all do |record|
seen[record.id] = true unless seen.key?(record.id)
end
end
alias uniq distinct
# Replace this collection with +other_array+. This will perform a diff
# and delete/add only records that have changed.
def replace(other_array)
other_array.each { |val| raise_on_type_mismatch!(val) }
original_target = load_target.dup
if owner.new_record?
replace_records(other_array, original_target)
else
transaction { replace_records(other_array, original_target) }
end
end
def include?(record)
if record.is_a?(reflection.klass)
if record.new_record?
include_in_memory?(record)
else
loaded? ? target.include?(record) : scope.exists?(record)
end
else
false
end
end
def load_target
if find_target?
@target = merge_target_lists(find_target, target)
end
loaded!
target
end
def add_to_target(record, skip_callbacks = false)
callback(:before_add, record) unless skip_callbacks
yield(record) if block_given?
if association_scope.distinct_value && index = @target.index(record)
@target[index] = record
else
@target << record
end
callback(:after_add, record) unless skip_callbacks
set_inverse_instance(record)
record
end
def scope(opts = {})
scope = super()
scope.none! if opts.fetch(:nullify, true) && null_scope?
scope
end
def null_scope?
owner.new_record? && !foreign_key_present?
end
private
def find_target
records = scope.to_a
records.each { |record| set_inverse_instance(record) }
records
end
# We have some records loaded from the database (persisted) and some that are
# in-memory (memory). The same record may be represented in the persisted array
# and in the memory array.
#
# So the task of this method is to merge them according to the following rules:
#
# * The final array must not have duplicates
# * The order of the persisted array is to be preserved
# * Any changes made to attributes on objects in the memory array are to be preserved
# * Otherwise, attributes should have the value found in the database
def merge_target_lists(persisted, memory)
return persisted if memory.empty?
return memory if persisted.empty?
persisted.map! do |record|
if mem_record = memory.delete(record)
((record.attribute_names & mem_record.attribute_names) - mem_record.changes.keys).each do |name|
mem_record[name] = record[name]
end
mem_record
else
record
end
end
persisted + memory
end
def create_record(attributes, raise = false, &block)
unless owner.persisted?
raise ActiveRecord::RecordNotSaved, "You cannot call create unless the parent is saved"
end
if attributes.is_a?(Array)
attributes.collect { |attr| create_record(attr, raise, &block) }
else
transaction do
add_to_target(build_record(attributes)) do |record|
yield(record) if block_given?
insert_record(record, true, raise)
end
end
end
end
# Do the relevant stuff to insert the given record into the association collection.
def insert_record(record, validate = true, raise = false)
raise NotImplementedError
end
def create_scope
scope.scope_for_create.stringify_keys
end
def delete_or_destroy(records, method)
records = records.flatten
records.each { |record| raise_on_type_mismatch!(record) }
existing_records = records.reject { |r| r.new_record? }
if existing_records.empty?
remove_records(existing_records, records, method)
else
transaction { remove_records(existing_records, records, method) }
end
end
def remove_records(existing_records, records, method)
records.each { |record| callback(:before_remove, record) }
delete_records(existing_records, method) if existing_records.any?
records.each { |record| target.delete(record) }
records.each { |record| callback(:after_remove, record) }
end
# Delete the given records from the association, using one of the methods :destroy,
# :delete_all or :nullify (or nil, in which case a default is used).
def delete_records(records, method)
raise NotImplementedError
end
def replace_records(new_target, original_target)
delete(target - new_target)
unless concat(new_target - target)
@target = original_target
raise RecordNotSaved, "Failed to replace #{reflection.name} because one or more of the " \
"new records could not be saved."
end
target
end
def concat_records(records)
result = true
records.flatten.each do |record|
raise_on_type_mismatch!(record)
add_to_target(record) do |rec|
result &&= insert_record(rec) unless owner.new_record?
end
end
result && records
end
def callback(method, record)
callbacks_for(method).each do |callback|
callback.call(method, owner, record)
end
end
def callbacks_for(callback_name)
full_callback_name = "#{callback_name}_for_#{reflection.name}"
owner.class.send(full_callback_name)
end
# Should we deal with assoc.first or assoc.last by issuing an independent query to
# the database, or by getting the target, and then taking the first/last item from that?
#
# If the args is just a non-empty options hash, go to the database.
#
# Otherwise, go to the database only if none of the following are true:
# * target already loaded
# * owner is new record
# * target contains new or changed record(s)
def fetch_first_nth_or_last_using_find?(args)
if args.first.is_a?(Hash)
true
else
!(loaded? ||
owner.new_record? ||
target.any? { |record| record.new_record? || record.changed? })
end
end
def include_in_memory?(record)
if reflection.is_a?(ActiveRecord::Reflection::ThroughReflection)
assoc = owner.association(reflection.through_reflection.name)
assoc.reader.any? { |source|
target = source.send(reflection.source_reflection.name)
target.respond_to?(:include?) ? target.include?(record) : target == record
} || target.include?(record)
else
target.include?(record)
end
end
# If the :inverse_of option has been
# specified, then #find scans the entire collection.
def find_by_scan(*args)
expects_array = args.first.kind_of?(Array)
ids = args.flatten.compact.map{ |arg| arg.to_s }.uniq
if ids.size == 1
id = ids.first
record = load_target.detect { |r| id == r.id.to_s }
expects_array ? [ record ] : record
else
load_target.select { |r| ids.include?(r.id.to_s) }
end
end
# Fetches the first/last using SQL if possible, otherwise from the target array.
def first_nth_or_last(type, *args)
args.shift if args.first.is_a?(Hash) && args.first.empty?
collection = fetch_first_nth_or_last_using_find?(args) ? scope : load_target
collection.send(type, *args).tap do |record|
set_inverse_instance record if record.is_a? ActiveRecord::Base
end
end
end
end
end
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