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 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.