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Rails 7: Trouble with JSON API Responses and ActiveModel Serializers on Nested Associations

👀 Views: 52 đŸ’Ŧ Answers: 1 📅 Created: 2025-06-08
ruby-on-rails active-model-serializers json-api ruby

I'm migrating some code and I'm not sure how to approach Hey everyone, I'm running into an issue that's driving me crazy. I'm building a Rails 7 API that returns JSON responses for a blog application... I'm using ActiveModel Serializers to serialize my objects, but I'm encountering issues with nested associations not being serialized correctly. For example, when fetching a post with its associated comments, the response doesn't include the comment attributes as expected. I have the following models set up: ```ruby class Post < ApplicationRecord has_many :comments end class Comment < ApplicationRecord belongs_to :post end ``` And my serializers look like this: ```ruby class PostSerializer < ActiveModel::Serializer attributes :id, :title, :body has_many :comments end class CommentSerializer < ActiveModel::Serializer attributes :id, :content, :created_at end ``` When I make a request to `/api/posts/1`, the JSON response only includes the post data but not the associated comments: ```json { "id": 1, "title": "First Post", "body": "This is the body of the first post." } ``` I expected the output to look like this, including the comments: ```json { "id": 1, "title": "First Post", "body": "This is the body of the first post.", "comments": [ { "id": 1, "content": "Great post!", "created_at": "2023-10-01T12:00:00Z" } ] } ``` I've checked the controller and confirmed that the comments are being loaded with the post. I'm using Rails 7.0.3 and the following code in my PostsController: ```ruby class Api::PostsController < ApplicationController def show post = Post.includes(:comments).find(params[:id]) render json: post, serializer: PostSerializer end end ``` I also tried calling `render json: post, include: :comments` directly, but that didn't work either. It seems like the association is not being serialized as intended. Am I missing something in the configuration, or is there a specific way to handle nested associations with ActiveModel Serializers in Rails 7? Any help would be greatly appreciated! This is part of a larger web app I'm building. How would you solve this? I'm developing on Ubuntu 20.04 with Ruby. Hoping someone can shed some light on this.