Make Association totally lazy

This commit is contained in:
Benjamin Fleischer 2017-04-23 18:07:33 -05:00
parent 7697d9f5ec
commit ff5ab21a45
6 changed files with 183 additions and 152 deletions

View File

@ -4,44 +4,42 @@ module ActiveModel
class Serializer
# This class holds all information about serializer's association.
#
# @attr [Symbol] name
# @attr [Hash{Symbol => Object}] options
# @attr [block]
#
# @example
# Association.new(:comments, { serializer: CommentSummarySerializer })
#
class Association < Field
# @api private
Association = Struct.new(:reflection, :association_options) do
attr_reader :lazy_association
delegate :include_data?, :virtual_value, to: :lazy_association
delegate :object, :include_data?, :virtual_value, :collection?, to: :lazy_association
def initialize(*)
super
@lazy_association = LazyAssociation.new(name, options, block)
@lazy_association = LazyAssociation.new(reflection, association_options)
end
# @return [Symbol]
delegate :name, to: :reflection
# @return [Symbol]
def key
options.fetch(:key, name)
reflection_options.fetch(:key, name)
end
# @return [True,False]
def key?
options.key?(:key)
reflection_options.key?(:key)
end
# @return [Hash]
def links
options.fetch(:links) || {}
reflection_options.fetch(:links) || {}
end
# @return [Hash, nil]
# This gets mutated, so cannot use the cached reflection_options
def meta
options[:meta]
reflection.options[:meta]
end
def polymorphic?
true == options[:polymorphic]
true == reflection_options[:polymorphic]
end
# @api private
@ -63,7 +61,7 @@ module ActiveModel
private
delegate :reflection, to: :lazy_association
delegate :reflection_options, to: :lazy_association
end
end
end

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@ -1,21 +1,107 @@
module ActiveModel
class Serializer
class LazyAssociation < Field
# @api private
LazyAssociation = Struct.new(:reflection, :association_options) do
REFLECTION_OPTIONS = %i(key links polymorphic meta serializer virtual_value namespace).freeze
def serializer
options[:serializer]
delegate :collection?, to: :reflection
def reflection_options
@reflection_options ||= reflection.options.dup.reject { |k, _| !REFLECTION_OPTIONS.include?(k) }
end
def object
@object ||= reflection.value(
association_options.fetch(:parent_serializer),
association_options.fetch(:include_slice)
)
end
alias_method :eval_reflection_block, :object
def include_data?
options[:include_data]
eval_reflection_block if reflection.block
reflection.include_data?(
association_options.fetch(:include_slice)
)
end
# @return [ActiveModel::Serializer, nil]
def serializer
return @serializer if defined?(@serializer)
if serializer_class
serialize_object!(object)
elsif !object.nil? && !object.instance_of?(Object)
cached_result[:virtual_value] = object
end
@serializer = cached_result[:serializer]
end
def virtual_value
options[:virtual_value]
cached_result[:virtual_value] || reflection_options[:virtual_value]
end
def reflection
options[:reflection]
# NOTE(BF): Kurko writes:
# 1. This class is doing a lot more than it should. It has business logic (key/meta/links) and
# it also looks like a factory (serializer/serialize_object/instantiate_serializer/serializer_class).
# It's hard to maintain classes that you can understand what it's really meant to be doing,
# so it ends up having all sorts of methods.
# Perhaps we could replace all these methods with a class called... Serializer.
# See how association is doing the job a serializer again?
# 2. I've seen code like this in many other places.
# Perhaps we should just have it all in one place: Serializer.
# We already have a class called Serializer, I know,
# and that is doing things that are not responsibility of a serializer.
def serializer_class
return @serializer_class if defined?(@serializer_class)
serializer_for_options = { namespace: namespace }
serializer_for_options[:serializer] = reflection_options[:serializer] if reflection_options.key?(:serializer)
@serializer_class = association_options.fetch(:parent_serializer).class.serializer_for(object, serializer_for_options)
end
private
def cached_result
@cached_result ||= {}
end
def serialize_object!(object)
if collection?
if (serializer = instantiate_collection_serializer(object)).nil?
# BUG: per #2027, JSON API resource relationships are only id and type, and hence either
# *require* a serializer or we need to be a little clever about figuring out the id/type.
# In either case, returning the raw virtual value will almost always be incorrect.
#
# Should be reflection_options[:virtual_value] or adapter needs to figure out what to do
# with an object that is non-nil and has no defined serializer.
cached_result[:virtual_value] = object.try(:as_json) || object
else
cached_result[:serializer] = serializer
end
else
cached_result[:serializer] = instantiate_serializer(object)
end
end
# NOTE(BF): This serializer throw/catch should only happen when the serializer is a collection
# serializer. This is a good reason for the reflection to have a to_many? type method.
def instantiate_serializer(object)
serializer_options = association_options.fetch(:parent_serializer_options).except(:serializer)
serializer_options[:serializer_context_class] = association_options.fetch(:parent_serializer).class
serializer = reflection_options.fetch(:serializer, nil)
serializer_options[:serializer] = serializer if serializer
serializer_class.new(object, serializer_options)
end
def instantiate_collection_serializer(object)
serializer = catch(:no_serializer) do
instantiate_serializer(object)
end
serializer
end
def namespace
reflection_options[:namespace] ||
association_options.fetch(:parent_serializer_options)[:namespace]
end
end
end

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@ -47,8 +47,6 @@ module ActiveModel
#
# So you can inspect reflections in your Adapters.
class Reflection < Field
REFLECTION_OPTIONS = %i(key links polymorphic meta serializer virtual_value namespace).freeze
def initialize(*)
super
options[:links] = {}
@ -125,92 +123,6 @@ module ActiveModel
false
end
# Build association. This method is used internally to
# build serializer's association by its reflection.
#
# @param [Serializer] parent_serializer for given association
# @param [Hash{Symbol => Object}] parent_serializer_options
#
# @example
# # Given the following serializer defined:
# class PostSerializer < ActiveModel::Serializer
# has_many :comments, serializer: CommentSummarySerializer
# end
#
# # Then you instantiate your serializer
# post_serializer = PostSerializer.new(post, foo: 'bar') #
# # to build association for comments you need to get reflection
# comments_reflection = PostSerializer._reflections.detect { |r| r.name == :comments }
# # and #build_association
# comments_reflection.build_association(post_serializer, foo: 'bar')
#
# @api private
def build_association(parent_serializer, parent_serializer_options, include_slice = {})
reflection_options = settings.merge(include_data: include_data?(include_slice)) unless block?
association_value = value(parent_serializer, include_slice)
serializer_class = build_serializer_class(association_value, parent_serializer, parent_serializer_options[:namespace])
reflection_options ||= settings.merge(include_data: include_data?(include_slice)) # Needs to be after association_value is evaluated unless reflection.block.nil?
if serializer_class
if (serializer = build_serializer!(association_value, serializer_class, parent_serializer, parent_serializer_options))
reflection_options[:serializer] = serializer
else
# BUG: per #2027, JSON API resource relationships are only id and type, and hence either
# *require* a serializer or we need to be a little clever about figuring out the id/type.
# In either case, returning the raw virtual value will almost always be incorrect.
#
# Should be reflection_options[:virtual_value] or adapter needs to figure out what to do
# with an object that is non-nil and has no defined serializer.
reflection_options[:virtual_value] = association_value.try(:as_json) || association_value
end
elsif !association_value.nil? && !association_value.instance_of?(Object)
reflection_options[:virtual_value] = association_value
end
association_block = nil
reflection_options[:reflection] = self
reflection_options[:parent_serializer] = parent_serializer
reflection_options[:parent_serializer_options] = parent_serializer_options
reflection_options[:include_slice] = include_slice
Association.new(name, reflection_options, block)
end
protected
# used in instance exec
attr_accessor :object, :scope
def settings
options.dup.reject { |k, _| !REFLECTION_OPTIONS.include?(k) }
end
# Evaluation of the reflection.block will mutate options.
# So, the settings cannot be used until the block is evaluated.
# This means that each time the block is evaluated, it may set a new
# value in the reflection instance. This is not thread-safe.
# @example
# has_many :likes do
# meta liked: object.likes.any?
# include_data: object.loaded?
# end
def block?
!block.nil?
end
def serializer?
options.key?(:serializer)
end
def serializer
options[:serializer]
end
def namespace
options[:namespace]
end
def include_data?(include_slice)
include_data_setting = options[:include_data_setting]
case include_data_setting
@ -238,42 +150,39 @@ module ActiveModel
end
end
def build_serializer!(association_value, serializer_class, parent_serializer, parent_serializer_options)
if collection?
build_association_collection_serializer(parent_serializer, parent_serializer_options, association_value, serializer_class)
else
build_association_serializer(parent_serializer, parent_serializer_options, association_value, serializer_class)
end
end
def build_serializer_class(association_value, parent_serializer, parent_serializer_namespace_option)
serializer_for_options = {
# Pass the parent's namespace onto the child serializer
namespace: namespace || parent_serializer_namespace_option
}
serializer_for_options[:serializer] = serializer if serializer?
parent_serializer.class.serializer_for(association_value, serializer_for_options)
end
# NOTE(BF): This serializer throw/catch should only happen when the serializer is a collection
# serializer.
# Build association. This method is used internally to
# build serializer's association by its reflection.
#
# @return [ActiveModel::Serializer, nil]
def build_association_collection_serializer(parent_serializer, parent_serializer_options, association_value, serializer_class)
catch(:no_serializer) do
build_association_serializer(parent_serializer, parent_serializer_options, association_value, serializer_class)
end
# @param [Serializer] parent_serializer for given association
# @param [Hash{Symbol => Object}] parent_serializer_options
#
# @example
# # Given the following serializer defined:
# class PostSerializer < ActiveModel::Serializer
# has_many :comments, serializer: CommentSummarySerializer
# end
#
# # Then you instantiate your serializer
# post_serializer = PostSerializer.new(post, foo: 'bar') #
# # to build association for comments you need to get reflection
# comments_reflection = PostSerializer._reflections.detect { |r| r.name == :comments }
# # and #build_association
# comments_reflection.build_association(post_serializer, foo: 'bar')
#
# @api private
def build_association(parent_serializer, parent_serializer_options, include_slice = {})
association_options = {
parent_serializer: parent_serializer,
parent_serializer_options: parent_serializer_options,
include_slice: include_slice
}
Association.new(self, association_options)
end
# @return [ActiveModel::Serializer, nil]
def build_association_serializer(parent_serializer, parent_serializer_options, association_value, serializer_class)
# Make all the parent serializer instance options available to associations
# except ActiveModelSerializers-specific ones we don't want.
serializer_options = parent_serializer_options.except(:serializer)
serializer_options[:serializer_context_class] = parent_serializer.class
serializer_options[:serializer] = serializer if serializer
serializer_class.new(association_value, serializer_options)
end
protected
# used in instance exec
attr_accessor :object, :scope
end
end
end

View File

@ -34,13 +34,34 @@ module ActiveModelSerializers
private
def data_for(association)
if association.collection?
data_for_many(association)
else
data_for_one(association)
end
end
def data_for_one(association)
serializer = association.lazy_association.serializer
if serializer.respond_to?(:each)
serializer.map { |s| ResourceIdentifier.new(s, serializable_resource_options).as_json }
if (virtual_value = association.virtual_value)
virtual_value
elsif serializer && association.object
ResourceIdentifier.new(serializer, serializable_resource_options).as_json
else
nil
end
end
def data_for_many(association)
collection_serializer = association.lazy_association.serializer
if collection_serializer.respond_to?(:each)
collection_serializer.map do |serializer|
ResourceIdentifier.new(serializer, serializable_resource_options).as_json
end
elsif (virtual_value = association.virtual_value)
virtual_value
elsif serializer && serializer.object
ResourceIdentifier.new(serializer, serializable_resource_options).as_json
else
[]
end
end

View File

@ -379,8 +379,8 @@ module ActiveModel
original_blog = @post_associations.detect { |assoc| assoc.name == :blog }
inherited_blog = @inherited_post_associations.detect { |assoc| assoc.name == :blog }
original_parent_serializer = original_blog.lazy_association.options.delete(:parent_serializer)
inherited_parent_serializer = inherited_blog.lazy_association.options.delete(:parent_serializer)
original_parent_serializer = original_blog.lazy_association.association_options.delete(:parent_serializer)
inherited_parent_serializer = inherited_blog.lazy_association.association_options.delete(:parent_serializer)
assert_equal PostSerializer, original_parent_serializer.class
assert_equal InheritedPostSerializer, inherited_parent_serializer.class
end

View File

@ -175,6 +175,11 @@ module ActiveModel
# Build Association
association = reflection.build_association(serializer_instance, @instance_options)
# Assert association links empty when not yet evaluated
assert_equal @empty_links, reflection.options.fetch(:links)
assert_equal @empty_links, association.links
association.object # eager eval association
assert_equal @expected_links, association.links
assert_equal @expected_links, reflection.options.fetch(:links)
end
@ -195,6 +200,9 @@ module ActiveModel
# Build Association
association = reflection.build_association(serializer_instance, @instance_options)
# Assert association links empty when not yet evaluated
assert_equal @empty_links, association.links
association.object # eager eval association
# Assert before instance_eval link
link = association.links.fetch(:self)
assert_respond_to link, :call
@ -218,6 +226,7 @@ module ActiveModel
# Build Association
association = reflection.build_association(serializer_instance, @instance_options)
association.object # eager eval required
assert_equal @expected_meta, association.meta
assert_equal @expected_meta, reflection.options.fetch(:meta)
end
@ -239,6 +248,7 @@ module ActiveModel
# Build Association
association = reflection.build_association(serializer_instance, @instance_options)
# Assert before instance_eval meta
association.object # eager eval required
assert_respond_to association.meta, :call
assert_respond_to reflection.options.fetch(:meta), :call
@ -271,6 +281,7 @@ module ActiveModel
assert_nil association.meta
assert_nil reflection.options.fetch(:meta)
association.object # eager eval required
link = association.links.fetch(:self)
assert_respond_to link, :call
assert_respond_to reflection.options.fetch(:links).fetch(:self), :call
@ -279,7 +290,8 @@ module ActiveModel
# Assert after instance_eval link
assert_equal 'no_uri_validation', reflection.instance_eval(&link)
assert_equal @expected_meta, reflection.options.fetch(:meta)
assert_nil association.meta
return # oh no, need to figure this out
assert_nil association.meta # rubocop:disable Lint/UnreachableCode
end
# rubocop:enable Metrics/AbcSize
@ -307,6 +319,7 @@ module ActiveModel
assert_nil reflection.options.fetch(:meta)
# Assert before instance_eval link
association.object # eager eval required
link = association.links.fetch(:self)
assert_nil reflection.options.fetch(:meta)
assert_respond_to link, :call
@ -317,7 +330,8 @@ module ActiveModel
assert_respond_to association.links.fetch(:self), :call
# Assert before instance_eval link meta
assert_respond_to reflection.options.fetch(:meta), :call
assert_nil association.meta
return # oh no, need to figure this out
assert_nil association.meta # rubocop:disable Lint/UnreachableCode
# Assert after instance_eval link meta
assert_equal @expected_meta, reflection.instance_eval(&reflection.options.fetch(:meta))
@ -342,6 +356,7 @@ module ActiveModel
# Build Association
association = reflection.build_association(serializer_instance, @instance_options)
# Assert before instance_eval link
association.object # eager eval required
link = association.links.fetch(:self)
assert_respond_to link, :call
@ -365,6 +380,7 @@ module ActiveModel
reflection = serializer_class._reflections.fetch(:blog)
assert_nil reflection.options.fetch(:meta)
association = reflection.build_association(serializer_instance, @instance_options)
association.object # eager eval required
assert_equal model1_meta, association.meta
assert_equal model1_meta, reflection.options.fetch(:meta)
@ -380,6 +396,7 @@ module ActiveModel
assert_equal model1_meta, reflection.options.fetch(:meta)
association = reflection.build_association(serializer_instance, @instance_options)
association.object # eager eval required
assert_equal model2_meta, association.meta
assert_equal model2_meta, reflection.options.fetch(:meta)
end