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