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
  verify :method => :post, :only => [ :destroy, :create, :update ],
         :redirect_to => { :action => :list }

  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 successfully created"
      redirect_to :action => "list"
    else
      render_scaffold('new')
    end
  end

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

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

    if @entry.save
      flash[:notice] = "Entry was successfully updated"
      redirect_to :action => "show", :id => @entry
    else
      render_scaffold('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 87

def scaffold(model_id, options = {})
  options.assert_valid_keys(:class_name, :suffix)

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

  unless options[:suffix]
    module_eval <<-"end_eval", __FILE__, __LINE__
      def index
        list
      end
    end_eval
  end
  
  module_eval <<-"end_eval", __FILE__, __LINE__
    
    verify :method => :post, :only => [ :destroy#{suffix}, :create#{suffix}, :update#{suffix} ],
           :redirect_to => { :action => :list#{suffix} }
    
  
    def list#{suffix}
      @#{singular_name}_pages, @#{plural_name} = paginate :#{plural_name}, :per_page => 10
      render#{suffix}_scaffold "list#{suffix}"
    end

    def show#{suffix}
      @#{singular_name} = #{class_name}.find(params[:id])
      render#{suffix}_scaffold
    end
    
    def destroy#{suffix}
      #{class_name}.find(params[:id]).destroy
      redirect_to :action => "list#{suffix}"
    end
    
    def new#{suffix}
      @#{singular_name} = #{class_name}.new
      render#{suffix}_scaffold
    end
    
    def create#{suffix}
      @#{singular_name} = #{class_name}.new(params[:#{singular_name}])
      if @#{singular_name}.save
        flash[:notice] = "#{class_name} was successfully created"
        redirect_to :action => "list#{suffix}"
      else
        render#{suffix}_scaffold('new')
      end
    end
    
    def edit#{suffix}
      @#{singular_name} = #{class_name}.find(params[:id])
      render#{suffix}_scaffold
    end
    
    def update#{suffix}
      @#{singular_name} = #{class_name}.find(params[:id])
      @#{singular_name}.attributes = params[:#{singular_name}]

      if @#{singular_name}.save
        flash[:notice] = "#{class_name} was successfully updated"
        redirect_to :action => "show#{suffix}", :id => @#{singular_name}
      else
        render#{suffix}_scaffold('edit')
      end
    end
    
    private
      def render#{suffix}_scaffold(action=nil)
        action ||= caller_method_name(caller)
        # logger.info ("testing template:" + "\#{self.class.controller_path}/\#{action}") if logger
        
        if template_exists?("\#{self.class.controller_path}/\#{action}")
          render_action(action)
        else
          @scaffold_class = #{class_name}
          @scaffold_singular_name, @scaffold_plural_name = "#{singular_name}", "#{plural_name}"
          @scaffold_suffix = "#{suffix}"
          add_instance_variables_to_assigns

          @template.instance_variable_set("@content_for_layout", @template.render_file(scaffold_path(action.sub(/#{suffix}$/, "")), false))

          if !active_layout.nil?
            render_file(active_layout, nil, true)
          else
            render_file(scaffold_path("layout"))
          end
        end
      end

      def scaffold_path(template_name)
        File.dirname(__FILE__) + "/templates/scaffolds/" + template_name + ".rhtml"
      end
      
      def caller_method_name(caller)
        caller.first.scan(/`(.*)'/).first.first # ' ruby-mode
      end
  end_eval
end