ruby on rails - How do I select which attributes I want for active model serializers relationships -

i using jsonapi format along active model serializers create api rails-api.

i have serializer shows specific post has many topics , currently, under relationships, lists topics. lists id , type. want show title of topic well.

some use include: 'topics' in controller, don't need full topic record, title.

question: how specify attributes want show topics?

what have

"data": {   "id": "26",   "type": "posts",   "attributes": {     "title": "test title 11"   },   "relationships": {     "topics": {       "data": [         {           "id": "1",           "type": "topics"         }       ]     }   } } 

what want

"data": {   "id": "26",   "type": "posts",   "attributes": {     "title": "test title 11"   },   "relationships": {     "topics": {       "data": [         {           "id": "1",           "type": "topics",           "title": "topic title"         }       ]     }   } } 

my current serializer classes edit: i'm after please.

class postserializer < activemodel::serializer   attributes :title    belongs_to :domain   belongs_to :user    has_many :topics, serializer: topicserializer    def topics     # asking   end end  class topicserializer < activemodel::serializer   attributes :title, :description    belongs_to :parent   has_many :children end 

one thing tried - there answer below makes work, not i'm after.

class postserializer < activemodel::serializer   attributes :title, :topics    belongs_to :domain   belongs_to :user    def topics     # answered below! thank   end end 

just make sure return hash or array of hashes so:

def videos     object.listing_videos.collect |lv|       {         id: lv.video.id,         name: lv.video.name,         wistia_id: lv.video.wistia_id,         duration: lv.video.duration,         wistia_hashed_id: lv.video.wistia_hashed_id,         description: lv.video.description,         thumbnail: lv.video.thumbnail       }     end   end