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