Serializers (Active Model Serializers) in Ruby on Rails - Mini Project: Build & Apply

Serializing User Data with Active Model Serializers

📖 Scenario: You are building a simple Rails API that sends user information as JSON to a frontend app. To make the JSON neat and easy to use, you will use Active Model Serializers.

🎯 Goal: Create a serializer for the User model that controls which user attributes are sent in the JSON response.

📋 What You'll Learn

Create a User model with specific attributes

Set a configuration variable for attributes to include

Write a serializer class using Active Model Serializers

Use the serializer in a controller to render JSON

💡 Why This Matters

🌍 Real World

APIs often need to send only specific parts of data to clients. Serializers help format and filter this data cleanly.

💼 Career

Understanding serializers is key for backend developers working with Rails APIs to deliver well-structured JSON to frontend or mobile apps.

1

Create the User model with attributes

Create a User model with these exact attributes: id, name, email, and age. Use attr_accessor to define them.

Ruby on Rails

# Define the User model with id, name, email, and age attributes
# Your code here

Need a hint?

Use attr_accessor to create readable and writable attributes for User.

2

Set attributes to include in serialization

Create a variable called USER_ATTRIBUTES as an array containing :id, :name, and :email. This will control which attributes the serializer sends.

Ruby on Rails

class User
  attr_accessor :id, :name, :email, :age

  def initialize(id, name, email, age)
    @id = id
    @name = name
    @email = email
    @age = age
  end
end

# Define USER_ATTRIBUTES array with :id, :name, and :email
# Your code here

Need a hint?

Use a constant array named USER_ATTRIBUTES with symbols for the attributes.

3

Create the UserSerializer class

Create a class called UserSerializer that inherits from ActiveModel::Serializer. Use attributes method with the USER_ATTRIBUTES array to specify which attributes to serialize.

Ruby on Rails

class UserSerializer < ActiveModel::Serializer
  # Use attributes method with USER_ATTRIBUTES
  # Your code here
end

Need a hint?

Use the splat operator * to pass the array elements as arguments to attributes.

4

Render JSON using the serializer in controller

In a controller action, create a User instance with id: 1, name: 'Alice', email: '[e-mail]', and age: 30. Render JSON using render json: user, serializer: UserSerializer.

Ruby on Rails

def show
  # Create user instance
  # Render JSON with UserSerializer
  # Your code here
end

Need a hint?

Create the user with exact values and use render json: with the serializer option.