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Add support for JSON API deserialization (experimental).
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‎CHANGELOG.md

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@@ -16,6 +16,7 @@ Breaking changes:
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Features:
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- [#1248](https://github.com/rails-api/active_model_serializers/pull/1248) Experimental: Add support for JSON API deserialization (@beauby)
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- [#1378](https://github.com/rails-api/active_model_serializers/pull/1378) Change association blocks
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to be evaluated in *serializer* scope, rather than *association* scope. (@bf4)
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* Syntax changes from e.g.

‎lib/active_model/serializer/adapter/json_api.rb

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@@ -6,6 +6,7 @@ class JsonApi < Base
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autoload :PaginationLinks
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autoload :FragmentCache
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autoload :Link
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autoload :Deserialization
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# TODO: if we like this abstraction and other API objects to it,
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# then extract to its own file and require it.

‎lib/active_model/serializer/adapter/json_api/deserialization.rb

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module ActiveModel
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class Serializer
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module Adapter
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class JsonApi
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# NOTE(Experimental):
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# This is an experimental feature. Both the interface and internals could be subject
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# to changes.
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module Deserialization
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InvalidDocument = Class.new(ArgumentError)
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module_function
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# Transform a JSON API document, containing a single data object,
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# into a hash that is ready for ActiveRecord::Base.new() and such.
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# Raises InvalidDocument if the payload is not properly formatted.
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#
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# @param [Hash|ActionController::Parameters] document
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# @param [Hash] options
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# only: Array of symbols of whitelisted fields.
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# except: Array of symbols of blacklisted fields.
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# keys: Hash of translated keys (e.g. :author => :user).
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# polymorphic: Array of symbols of polymorphic fields.
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# @return [Hash]
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#
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# @example
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# document = {
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# data: {
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# id: 1,
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# type: 'post',
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# attributes: {
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# title: 'Title 1',
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# date: '2015-12-20'
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# },
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# associations: {
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# author: {
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# data: {
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# type: 'user',
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# id: 2
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# }
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# },
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# second_author: {
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# data: nil
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# },
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# comments: {
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# data: [{
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# type: 'comment',
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# id: 3
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# },{
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# type: 'comment',
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# id: 4
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# }]
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# }
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# }
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# }
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# }
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#
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# parse(document) #=>
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# # {
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# # title: 'Title 1',
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# # date: '2015-12-20',
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# # author_id: 2,
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# # second_author_id: nil
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# # comment_ids: [3, 4]
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# # }
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#
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# parse(document, only: [:title, :date, :author],
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# keys: { date: :published_at },
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# polymorphic: [:author]) #=>
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# # {
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# # title: 'Title 1',
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# # published_at: '2015-12-20',
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# # author_id: '2',
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# # author_type: 'people'
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# # }
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#
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def parse!(document, options = {})
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parse(document, options) do |invalid_payload, reason|
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fail InvalidDocument, "Invalid payload (#{reason}): #{invalid_payload}"
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end
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end
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# Same as parse!, but returns an empty hash instead of raising InvalidDocument
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# on invalid payloads.
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def parse(document, options = {})
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document = document.dup.permit!.to_h if document.is_a?(ActionController::Parameters)
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validate_payload(document) do |invalid_document, reason|
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yield invalid_document, reason if block_given?
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return {}
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end
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primary_data = document['data']
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attributes = primary_data['attributes'] || {}
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attributes['id'] = primary_data['id'] if primary_data['id']
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relationships = primary_data['relationships'] || {}
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filter_fields(attributes, options)
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filter_fields(relationships, options)
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hash = {}
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hash.merge!(parse_attributes(attributes, options))
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hash.merge!(parse_relationships(relationships, options))
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hash
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end
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# Checks whether a payload is compliant with the JSON API spec.
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#
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# @api private
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# rubocop:disable Metrics/CyclomaticComplexity
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def validate_payload(payload)
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unless payload.is_a?(Hash)
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yield payload, 'Expected hash'
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return
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end
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primary_data = payload['data']
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unless primary_data.is_a?(Hash)
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yield payload, { data: 'Expected hash' }
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return
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end
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attributes = primary_data['attributes'] || {}
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unless attributes.is_a?(Hash)
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yield payload, { data: { attributes: 'Expected hash or nil' } }
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return
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end
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relationships = primary_data['relationships'] || {}
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unless relationships.is_a?(Hash)
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yield payload, { data: { relationships: 'Expected hash or nil' } }
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return
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end
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relationships.each do |(key, value)|
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unless value.is_a?(Hash) && value.key?('data')
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yield payload, { data: { relationships: { key => 'Expected hash with :data key' } } }
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end
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end
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end
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# rubocop:enable Metrics/CyclomaticComplexity
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# @api private
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def filter_fields(fields, options)
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if (only = options[:only])
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fields.slice!(*Array(only).map(&:to_s))
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elsif (except = options[:except])
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fields.except!(*Array(except).map(&:to_s))
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end
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end
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# @api private
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def field_key(field, options)
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(options[:keys] || {}).fetch(field.to_sym, field).to_sym
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end
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# @api private
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def parse_attributes(attributes, options)
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attributes
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.map { |(k, v)| { field_key(k, options) => v } }
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.reduce({}, :merge)
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end
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# Given an association name, and a relationship data attribute, build a hash
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# mapping the corresponding ActiveRecord attribute to the corresponding value.
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#
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# @example
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# parse_relationship(:comments, [{ 'id' => '1', 'type' => 'comments' },
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# { 'id' => '2', 'type' => 'comments' }],
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# {})
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# # => { :comment_ids => ['1', '2'] }
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# parse_relationship(:author, { 'id' => '1', 'type' => 'users' }, {})
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# # => { :author_id => '1' }
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# parse_relationship(:author, nil, {})
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# # => { :author_id => nil }
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# @param [Symbol] assoc_name
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# @param [Hash] assoc_data
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# @param [Hash] options
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# @return [Hash{Symbol, Object}]
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#
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# @api private
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def parse_relationship(assoc_name, assoc_data, options)
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prefix_key = field_key(assoc_name, options).to_s.singularize
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hash =
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if assoc_data.is_a?(Array)
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{ "#{prefix_key}_ids".to_sym => assoc_data.map { |ri| ri['id'] } }
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else
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{ "#{prefix_key}_id".to_sym => assoc_data ? assoc_data['id'] : nil }
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end
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polymorphic = (options[:polymorphic] || []).include?(assoc_name.to_sym)
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hash.merge!("#{prefix_key}_type".to_sym => assoc_data['type']) if polymorphic
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hash
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end
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# @api private
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def parse_relationships(relationships, options)
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relationships
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.map { |(k, v)| parse_relationship(k, v['data'], options) }
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.reduce({}, :merge)
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end
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end
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end
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end
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end
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end

‎lib/active_model_serializers.rb

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extend ActiveSupport::Autoload
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autoload :Model
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autoload :Callbacks
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autoload :Deserialization
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autoload :Logging
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end
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‎lib/active_model_serializers/deserialization.rb

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module ActiveModelSerializers
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module Deserialization
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module_function
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def jsonapi_parse(*args)
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ActiveModel::Serializer::Adapter::JsonApi::Deserialization.parse(*args)
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end
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def jsonapi_parse!(*args)
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ActiveModel::Serializer::Adapter::JsonApi::Deserialization.parse!(*args)
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end
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end
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end

‎test/action_controller/json_api/deserialization_test.rb

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require 'test_helper'
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module ActionController
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module Serialization
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class JsonApi
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class DeserializationTest < ActionController::TestCase
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class DeserializationTestController < ActionController::Base
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def render_parsed_payload
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parsed_hash = ActiveModelSerializers::Deserialization.jsonapi_parse(params)
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render json: parsed_hash
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end
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end
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tests DeserializationTestController
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def test_deserialization
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hash = {
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'data' => {
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'type' => 'photos',
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'id' => 'zorglub',
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'attributes' => {
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'title' => 'Ember Hamster',
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'src' => 'http://example.com/images/productivity.png'
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},
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'relationships' => {
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'author' => {
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'data' => nil
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},
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'photographer' => {
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'data' => { 'type' => 'people', 'id' => '9' }
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},
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'comments' => {
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'data' => [
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{ 'type' => 'comments', 'id' => '1' },
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{ 'type' => 'comments', 'id' => '2' }
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]
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}
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}
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}
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}
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post :render_parsed_payload, hash
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response = JSON.parse(@response.body)
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expected = {
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'id' => 'zorglub',
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'title' => 'Ember Hamster',
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'src' => 'http://example.com/images/productivity.png',
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'author_id' => nil,
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'photographer_id' => '9',
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'comment_ids' => %w(1 2)
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}
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assert_equal(expected, response)
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end
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end
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end
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end
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end

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