render_component

render_component copied to clipboard

Components allow you to call other actions for their rendered response while executing another action. You can either delegate the entire response rendering or you can mix a partial response in with your other content.

class WeblogController < ActionController::Base # Performs a method and then lets hello_world output its render def delegate_action do_other_stuff_before_hello_world render_component :controller => "greeter", :action => "hello_world", :params => { :person => "david" } end end

class GreeterController < ActionController::Base def hello_world render :text => "#{params[:person]} says, Hello World!" end end

The same can be done in a view to do a partial rendering:

Let's see a greeting: <%= render_component :controller => "greeter", :action => "hello_world" %>

It is also possible to specify the controller as a class constant, bypassing the inflector code to compute the controller class at runtime:

<%= render_component :controller => GreeterController, :action => "hello_world" %>

== When to use components

Components should be used with care. They're significantly slower than simply splitting reusable parts into partials and conceptually more complicated. Don't use components as a way of separating concerns inside a single application. Instead, reserve components to those rare cases where you truly have reusable view and controller elements that can be employed across many applications at once.

So to repeat: Components are a special-purpose approach that can often be replaced with better use of partials and filters.

Copyright (c) 2007 David Heinemeier Hansson, released under the MIT license