Rails API: Adding array of objects to json return

Question

I'm using the built-in API with Rails 5.

I'm learning to write APIs with Rails and I'm trying to figure out how to add a property to my json return that is an array of objects.

I've got a model for Users and Posts.

What I would like to do is return all the posts associated with a users.

What I've done is in posts_controller.rb I've got a method that gets the userID form the URL and returns json that looks like:

[{"id":1,"content":"My first post!","user":{"id":1,"firstname":"Jody","lastname":"White","email":"[email protected]","fullname_firstname_first":"Jody White"}},{"id":2,"content":"Rails School is awesome!","user":{"id":1,"firstname":"Jody","lastname":"White","email":"[email protected]","fullname_firstname_first":"Jody White"}}]

But what I want is to return that looks like this:

{
    firstname: "Jody",
    lastname: "White",
    email: "whatever",
    posts: [{
        "id":1,"content":"My first post!"
        },
        {
            "id":2,"content":"Rails School is awesome!"
        }
    ]
}

How do I go about, or can I, getting the data to return like that?

user.rb model

class User < ApplicationRecord
  attr_accessor :fullname_firstname_first

  has_many :posts

  def fullname_firstname_first
    fullname_firstname_first = firstname + " " + lastname
  end
end

post.rb model

class Post < ApplicationRecord
  belongs_to :user
end

users_controller.rb

class UsersController < ApplicationController
  before_action :set_user, only: [:show, :update, :destroy]

  # GET /users
  def index
    @users = User.all
    render json: @users, include: :posts
  end

  # GET /users/1
  def show
    @user = User.find(params[:id])
    render json: @user, include: :posts
  end
end

Can you post your models, showing the associations involved, please? We probably don't need to see full models. — user483040
– user483040, Commented Aug 23, 2016 at 14:08

Christian-G · Accepted Answer · 2016-08-23 14:44:29Z

4

Assuming you defined this structure:

class Post < ApplicationRecord
  belongs_to :user
end

class User < ApplicationRecord
  has_many :posts
end

You could achieve a structure like you wanted with the Active Record serialization method to_json. The use would be in a respond_to block in your controller.

format.json { render json: @users, include: :posts }

So your UsersController would look something like this:

class UsersController < ApplicationController
  def index
    # all users with all their posts 
    @users = User.all
    respond_to do |format|
      format.json { render json: @users, include: :posts }
    end
  end

  def show
    # single user and their posts
    @user = User.find(params[:id])
    respond_to do |format|
      format.json { render json: @user, include: :posts }
    end
  end
end

Update

Instead of using the repond_to block you can alternatively use:

render json: @users, include: :posts

Your controller will then look like:

class UsersController < ApplicationController
  def index
    # all users with all their posts 
    @users = User.all
    render json: @users, include: :posts
  end

  def show
    # single user and their posts
    @user = User.find(params[:id])
    render json: @user, include: :posts
  end
end

edited Aug 23, 2016 at 14:44

answered Aug 23, 2016 at 13:35

Christian-G

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6 Comments

James White Over a year ago

In my show method I changed render json: @user to render json: @user.posts and I'm getting the same format as my original post. If it matters I'm using Active Model Serializer.

James White Over a year ago

I'm using Rails 5 and it looks like respond_to is deprecated? I found a post saying if I wanted to use respond_to I needed to add include ActionController::MimeResponds to application_controller.rb but when I do I get

"status":406,"error":"Not Acceptable","exception":"#\u003cActionController::UnknownFormat: ActionController::UnknownFormat\u003e"

James White Over a year ago

@Christian-G I've got my controller and methods looking like yours now but I'm not getting the posts included in the response. See my edited original post for my models if that helps.

Christian-G Over a year ago

What does your controller look like now?

James White Over a year ago

@Christian-G My original post has been updates with a partial of the users_controller.rb file

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