CrudResponder - DRYing controller actions. Now in gem https://github.com/olegantonyan/crud_responder

crud_responder.rb

# lib/crud_responder.rb
module CrudResponder
  include ActionView::Helpers::TextHelper
  
  protected

  def crud_respond(object, options = {})
    method = options.fetch(:method, method_by_caller(caller))
    success_url = options.fetch(:success_url) { default_redirect_url(method, object) }
    error_action = options.fetch(:error_action) { default_render_action(method, object) }

    if perform(caller, object, method)
      redirect_to success_url
    else
      render error_action
    end
  end

  private

  def object_index_url object
    polymorphic_url(object.class)
  rescue NoMethodError
    nil
  end

  def object_url object
    polymorphic_url(object)
  rescue NoMethodError
    nil
  end

  def default_redirect_url(method, object)
    if method == :destroy
      object_index_url(object)
    else
      object_url(object)
    end || :back
  end

  def default_render_action(method, object)
    if object.persisted?
      :edit
    else
      :new
    end
  end

  def caller_name(_caller)
    _caller[0][/`.*'/][1..-2]
  end

  def method_by_caller(_caller)
    if caller_name(_caller) =~ /destroy/
      :destroy
    else
      :save
    end
  end

  def perform(_caller, object, method)
    ok = object.public_send(method)
    t_key = "flash.actions.#{action_by_caller(_caller)}.#{ok ? 'notice' : 'alert'}"
    if ok
      flash_success I18n.t(t_key, resource_name: resoucre_name_by_object(object))
    else
      flash_error I18n.t(t_key, resource_name: resoucre_name_by_object(object), errors: object.errors.full_messages.to_sentence)
    end
    ok
  end

  def action_by_caller(_caller)
    case caller_name(_caller)
    when /destroy/
      :destroy
    when /update/
      :update
    when /create/
      :create
    else
      "unknown_action_from_#{caller_name(_caller)}".to_sym
    end
  end

  def resoucre_name_by_object(object)
    object.class.to_s
  end
  
  def flash_success msg
    flash[:notice] = truncate_message(msg)
  end

  def flash_error msg
    flash[:alert] = truncate_message(msg)
  end

  def truncate_message msg
    truncate(msg.to_s, length: 256, escape: false)
  end

end

posts_controller.rb

# app/controllers/posts_controller.rb
class PostsController < ApplicationController
  include CrudResponder
  
  def create
    @post = Post.new(post_params)
    crud_respond @post # will be saved inside `crud_respond` + appropriate flash message will be shown + redirecte or render appropriate action
  end
  
  def update
    @post = Post.find(params[:id])
    @post.assign_attributes(post_params)
    crud_respond @post 
  end
  
  def destroy
     @post = Post.find(params[:id])
     crud_respond @post 
  end
  
end