Rails as_json API Example

example.md

Rails as_json API Example

Returns a hash representing a model and it's associated data. Useful for building an JSON API.

Associations

class User < ApplicationRecord
  has_many :injuries
  has_many :appointments, through: :injuries

  has_one :active_injury, -> { active }, class_name: "Injury"
end

class Injury < ApplicationRecord
  belongs_to :user

  has_many :appointments
end

Controller

class UserController < ApplicationController
  def show
    @user = User.find(params[:id])

    render json: {
      patient: @user.as_json(
        only: [
          :first_name,
          :last_name,
          :email,
          :phone_number,
          :timezone,
          :latest_activity_on
        ],
        include: {
          active_injury: {
            include: :appointments
          }
        }
      )
    }  
  end
end

Output

{
  "patient": {
    "first_name": "Alice",
    "last_name": "Johnson",
    "email": "patient@example.com",
    "phone_number": "5554443333",
    "timezone": "America/Juneau",
    "latest_activity_on": "2022-02-17",
    "active_injury": {
      "id": 2073,
      "user_id": 2782,
      "created_at": "2022-02-10T21:14:07Z",
      "updated_at": "2022-02-17T21:14:07Z",
      "appointments": [
        {
          "id": 810,
          "starts_at": "2022-02-24T21:14:07Z",
          "created_at": "2022-02-17T21:14:07Z",
          "updated_at": "2022-02-17T21:14:07Z",
          "injury_id": 2073,
        }
      ]
    }
  }
}

What's Going On Here?

• The as_json method returns a hash representing the model.
• The only option allows us to specificy what attribues we want to return. Note the the created_at, updated_at and id attributes are not returned. The include option allows us to load associated records. Note that second level and higher order associations work as well.