35. Controller Filters and Callbacks

1class ArticlesController < ApplicationController
2  before_action :authenticate_user!
3  before_action :set_article, only: [:show, :edit, :update, :destroy]
4  before_action :authorize_author, only: [:edit, :update, :destroy]
5  
6  def show
7    # @article is already set
8  end
9  
10  def edit
11    # @article is set and user is authorized
12  end
13  
14  def update
15    if @article.update(article_params)
16      redirect_to @article
17    else
18      render :edit
19    end
20  end
21  
22  private
23  
24  def set_article
25    @article = Article.find(params[:id])
26  end
27  
28  def authorize_author
29    unless @article.user == current_user
30      redirect_to articles_path, alert: "Not authorized"
31    end
32  end
33end

1class ArticlesController < ApplicationController
2  # Only for specific actions
3  before_action :authenticate_user!, only: [:new, :create, :edit, :update, :destroy]
4  
5  # Except for specific actions
6  before_action :authenticate_user!, except: [:index, :show]
7  
8  # With conditions
9  before_action :check_premium, if: :premium_content?
10  before_action :log_request, unless: :admin_user?
11  
12  # With lambda
13  before_action :track_view, if: -> { request.format.html? }
14  
15  private
16  
17  def premium_content?
18    @article&.premium?
19  end
20  
21  def admin_user?
22    current_user&.admin?
23  end
24end

1class ArticlesController < ApplicationController
2  after_action :track_view, only: [:show]
3  after_action :log_response, if: -> { Rails.env.development? }
4  
5  def show
6    @article = Article.find(params[:id])
7  end
8  
9  private
10  
11  def track_view
12    @article.increment!(:views_count)
13  end
14  
15  def log_response
16    Rails.logger.info "Response: #{response.status}"
17  end
18end

1class ArticlesController < ApplicationController
2  around_action :with_timing
3  around_action :catch_exceptions
4  
5  def index
6    @articles = Article.all
7  end
8  
9  private
10  
11  def with_timing
12    start = Time.current
13    yield  # Execute the action
14    duration = Time.current - start
15    Rails.logger.info "Action took #{duration}s"
16  end
17  
18  def catch_exceptions
19    yield
20  rescue StandardError => e
21    Rails.logger.error "Error: #{e.message}"
22    redirect_to root_path, alert: "Something went wrong"
23  end
24end

1class ApplicationController < ActionController::Base
2  before_action :authenticate_user!
3end
4
5class PublicController < ApplicationController
6  skip_before_action :authenticate_user!
7end
8
9class ArticlesController < ApplicationController
10  skip_before_action :authenticate_user!, only: [:index, :show]
11end

1class ApplicationController < ActionController::Base
2  before_action :set_locale
3  before_action :authenticate_user!
4end
5
6class ArticlesController < ApplicationController
7  # Runs BEFORE parent filters
8  prepend_before_action :check_maintenance_mode
9  
10  # Runs AFTER parent filters (default behavior)
11  before_action :set_article
12  # Same as: append_before_action :set_article
13end

1class ApplicationController < ActionController::Base
2  before_action :authenticate_user!
3  
4  private
5  
6  def authenticate_user!
7    unless current_user
8      store_location
9      redirect_to login_path, alert: "Please log in"
10    end
11  end
12  
13  def current_user
14    @current_user ||= User.find_by(id: session[:user_id])
15  end
16  
17  def store_location
18    session[:return_to] = request.fullpath if request.get?
19  end
20end

1class ArticlesController < ApplicationController
2  before_action :set_article, only: [:show, :edit, :update, :destroy]
3  before_action :require_author, only: [:edit, :update, :destroy]
4  
5  private
6  
7  def require_author
8    unless @article.user == current_user || current_user.admin?
9      redirect_to @article, alert: "You can't edit this article"
10    end
11  end
12end

1class ArticlesController < ApplicationController
2  before_action :set_article, only: [:show, :edit, :update, :destroy]
3  before_action :set_categories, only: [:new, :edit, :create, :update]
4  
5  private
6  
7  def set_article
8    @article = Article.find(params[:id])
9  rescue ActiveRecord::RecordNotFound
10    redirect_to articles_path, alert: "Article not found"
11  end
12  
13  def set_categories
14    @categories = Category.all
15  end
16end

1class ApiController < ApplicationController
2  before_action :set_default_format
3  before_action :authenticate_api_key!
4  
5  private
6  
7  def set_default_format
8    request.format = :json unless params[:format]
9  end
10  
11  def authenticate_api_key!
12    api_key = request.headers["X-API-Key"]
13    head :unauthorized unless valid_api_key?(api_key)
14  end
15end

1class ApplicationController < ActionController::Base
2  after_action :track_action
3  
4  private
5  
6  def track_action
7    Analytics.track(
8      user_id: current_user&.id,
9      action: "#{controller_name}##{action_name}",
10      path: request.path,
11      referrer: request.referrer
12    )
13  end
14end

1class ArticlesController < ApplicationController
2  before_action :set_cache_headers, only: [:show]
3  
4  private
5  
6  def set_cache_headers
7    response.headers["Cache-Control"] = "public, max-age=3600"
8  end
9end