customize_model_serialization

🎨 Customize Rails Model JSON with as_json and to_json

Rails’ as_json and to_json methods let you fine‑tune how your ActiveRecord objects are serialized. Use the only, except, methods, and include options to shape payloads precisely for your API consumers.

class User < ApplicationRecord
  def as_json(options = {})
    super(
      only: [:id, :name, :email],         # include only these attributes
      methods: [:full_name],               # include custom method
      include: {                           # nest associated models
        posts: { only: [:id, :title] }
      }
    )
  end

  def full_name
    "#{first_name} #{last_name}"
  end
end

# Controller usage
render json: @user, status: :ok

By overriding as_json, you ensure consistent serialization across calls and can avoid leaking sensitive fields.