Ruby Rails Application

# Active Record Queries

## Active Record Queries

```ruby
# app/services/post_service.rb
class PostService
  def self.get_user_posts(user_id, status: nil)
    posts = Post.by_author(user_id)
    posts = posts.where(status: status) if status.present?
    posts.recent
  end

  def self.trending_posts(limit: 10)
    Post.published
        .joins(:comments)
        .group('posts.id')
        .order('COUNT(comments.id) DESC')
        .limit(limit)
  end

  def self.search_posts(query)
    Post.published
        .where("title ILIKE ? OR content ILIKE ?", "%#{query}%", "%#{query}%")
        .recent
  end

  def self.archive_old_drafts(days: 30)
    Post.where(status: :draft)
        .where('created_at < ?', days.days.ago)
        .update_all(status: :archived)
  end
end

# Usage
posts = Post.includes(:user).recent.limit(10)
recent_comments = Comment.where(post_id: post.id).order(created_at: :desc).limit(5)
```


# Authentication with JWT

## Authentication with JWT

```ruby
# app/controllers/application_controller.rb
class ApplicationController < ActionController::API
  include ActionController::Cookies

  SECRET_KEY = Rails.application.secrets.secret_key_base

  def encode_token(user_id)
    payload = { user_id: user_id, exp: 24.hours.from_now.to_i }
    JWT.encode(payload, SECRET_KEY, 'HS256')
  end

  def decode_token(token)
    begin
      JWT.decode(token, SECRET_KEY, true, { algorithm: 'HS256' })
    rescue JWT::ExpiredSignature, JWT::DecodeError
      nil
    end
  end

  def authenticate_request
    header = request.headers['Authorization']
    token = header.split(' ').last if header.present?

    decoded = decode_token(token)
    if decoded
      @current_user_id = decoded[0]['user_id']
      @current_user = User.find(@current_user_id)
    else
      render json: { error: 'Unauthorized' }, status: :unauthorized
    end
  end

  def current_user
    @current_user
  end

  def logged_in?
    current_user.present?
  end
end

# config/routes.rb
Rails.application.routes.draw do
  namespace :api do
    namespace :v1 do
      post 'auth/login', to: 'auth#login'
      post 'auth/register', to: 'auth#register'

      resources :users
      resources :posts do
        member do
          patch :publish
        end
        resources :comments, only: [:index, :create, :destroy]
      end
    end
  end
end
```


# Controllers with RESTful Actions

## Controllers with RESTful Actions

```ruby
# app/controllers/api/v1/users_controller.rb
module Api
  module V1
    class UsersController < ApplicationController
      before_action :authenticate_request, except: [:create]
      before_action :set_user, only: [:show, :update, :destroy]
      before_action :authorize_user!, only: [:update, :destroy]

      def index
        users = User.all
        users = users.where("email ILIKE ?", "%#{params[:q]}%") if params[:q].present?
        users = users.page(params[:page]).per(params[:limit] || 20)

        render json: {
          data: users,
          pagination: pagination_data(users)
        }
      end

      def show
        render json: @user
      end

      def create
        user = User.new(user_params)

        if user.save
          token = encode_token(user.id)
          render json: {
            user: user,
            token: token
          }, status: :created
        else
          render json: { errors: user.errors.full_messages }, status: :unprocessable_entity
        end
      end

      def update
        if @user.update(user_params)
          render json: @user
        else
          render json: { errors: @user.errors.full_messages }, status: :unprocessable_entity
        end
      end

      def destroy
        @user.destroy
        head :no_content
      end

      private

      def set_user
        @user = User.find(params[:id])
      rescue ActiveRecord::RecordNotFound
        render json: { error: 'User not found' }, status: :not_found
      end

      def authorize_user!
        unless current_user.id == @user.id || c