Module: ActionController::Scaffolding::ClassMethods

Defined in:
lib/action_controller/scaffolding.rb

Overview

Scaffolding is a way to quickly put an Active Record class online by providing a series of standardized actions for listing, showing, creating, updating, and destroying objects of the class. These standardized actions come with both controller logic and default templates that through introspection already know which fields to display and which input types to use. Example:

class WeblogController < ActionController::Base
  scaffold :entry
end

This tiny piece of code will add all of the following methods to the controller:

class WeblogController < ActionController::Base
  def index
    list
  end

  def list
    @entries = Entry.find_all
    render_scaffold "list"
  end

  def show
    @entry = Entry.find(@params["id"])
    render_scaffold
  end

  def destroy
    Entry.find(@params["id"]).destroy
    redirect_to :action => "list"
  end

  def new
    @entry = Entry.new
    render_scaffold
  end

  def create
    @entry = Entry.new(@params["entry"])
    if @entry.save
      flash["notice"] = "Entry was succesfully created"
      redirect_to :action => "list"
    else
      render "entry/new"
    end
  end

  def edit
    @entry = Entry.find(@params["id"])
    render_scaffold
  end

  def update
    @entry = Entry.find(@params["entry"]["id"])
    @entry.attributes = @params["entry"]

    if @entry.save
      flash["notice"] = "Entry was succesfully updated"
      redirect_to :action => "show/" + @entry.id.to_s
    else
      render "entry/edit"
    end
  end
end

The render_scaffold method will first check to see if you’ve made your own template (like “weblog/show.rhtml” for the show action) and if not, then render the generic template for that action. This gives you the possibility of using the scaffold while you’re building your specific application. Start out with a totally generic setup, then replace one template and one action at a time while relying on the rest of the scaffolded templates and actions.

Instance Method Summary collapse

Instance Method Details

#scaffold(model_id, options = {}) ⇒ Object

Adds a swath of generic CRUD actions to the controller. The model_id is automatically converted into a class name unless one is specifically provide through options[:class_name]. So scaffold :post would use Post as the class and @post/@posts for the instance variables.

It’s possible to use more than one scaffold in a single controller by specifying options[:suffix] = true. This will make scaffold :post, :suffix => true use method names like list_post, show_post, and create_post instead of just list, show, and post. If suffix is used, then no index method is added.



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# File 'lib/action_controller/scaffolding.rb', line 84

def scaffold(model_id, options = {})
  validate_options([ :class_name, :suffix ], options.keys)

  require "#{model_id.id2name}" rescue logger.warn "Couldn't auto-require #{model_id.id2name}.rb" unless logger.nil?

  singular_name = model_id.id2name
  class_name    = options[:class_name] || Inflector.camelize(singular_name)
  plural_name   = Inflector.pluralize(singular_name)
  suffix        = options[:suffix] ? "_#{singular_name}" : ""

  unless options[:suffix]
    module_eval "      def index\n        list\n      end\n    end_eval\n  end\n  \n  module_eval <<-\"end_eval\", __FILE__, __LINE__\n    def list\#{suffix}\n      @\#{plural_name} = \#{class_name}.find_all\n      render\#{suffix}_scaffold \"list\#{suffix}\"\n    end\n\n    def show\#{suffix}\n      @\#{singular_name} = \#{class_name}.find(@params[\"id\"])\n      render\#{suffix}_scaffold\n    end\n    \n    def destroy\#{suffix}\n      \#{class_name}.find(@params[\"id\"]).destroy\n      redirect_to :action => \"list\#{suffix}\"\n    end\n    \n    def new\#{suffix}\n      @\#{singular_name} = \#{class_name}.new\n      render\#{suffix}_scaffold\n    end\n    \n    def create\#{suffix}\n      @\#{singular_name} = \#{class_name}.new(@params[\"\#{singular_name}\"])\n      if @\#{singular_name}.save\n        flash[\"notice\"] = \"\#{class_name} was succesfully created\"\n        redirect_to :action => \"list\#{suffix}\"\n      else\n        render \"\#{singular_name}/new\#{suffix}\"\n      end\n    end\n    \n    def edit\#{suffix}\n      @\#{singular_name} = \#{class_name}.find(@params[\"id\"])\n      render\#{suffix}_scaffold\n    end\n    \n    def update\#{suffix}\n      @\#{singular_name} = \#{class_name}.find(@params[\"\#{singular_name}\"][\"id\"])\n      @\#{singular_name}.attributes = @params[\"\#{singular_name}\"]\n\n      if @\#{singular_name}.save\n        flash[\"notice\"] = \"\#{class_name} was succesfully updated\"\n        redirect_to :action => \"show\#{suffix}/\" + @\#{singular_name}.id.to_s\n      else\n        render \"\#{singular_name}/edit\#{suffix}\"\n      end\n    end\n    \n    private\n      def render\#{suffix}_scaffold(action = caller_method_name(caller))\n        if template_exists?(\"\\\#{controller_name}/\\\#{action}\")\n          render_action(action)\n        else\n          @scaffold_class = \#{class_name}\n          @scaffold_singular_name, @scaffold_plural_name = \"\#{singular_name}\", \"\#{plural_name}\"\n          @scaffold_suffix = \"\#{suffix}\"\n          add_instance_variables_to_assigns\n\n          @content_for_layout = @template.render_file(scaffold_path(action.sub(/\#{suffix}$/, \"\")), false)\n          self.active_layout ? render_file(self.active_layout, \"200 OK\", true) : render_file(scaffold_path(\"layout\"))\n        end\n      end\n      \n      def scaffold_path(template_name)\n        File.dirname(__FILE__) + \"/templates/scaffolds/\" + template_name + \".rhtml\"\n      end\n      \n      def caller_method_name(caller)\n        caller.first.scan(/`(.*)'/).first.first # ' ruby-mode\n      end\n  end_eval\nend\n", __FILE__, __LINE__