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Components allow you to call other actions for their rendered response while executing another action. You can either delegate
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the entire response rendering or you can mix a partial response in with your other content.
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class WeblogController < ActionController::Base
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# Performs a method and then lets hello_world output its render
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def delegate_action
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do_other_stuff_before_hello_world
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render_component :controller => "greeter", :action => "hello_world", :params => { :person => "david" }
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end
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end
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class GreeterController < ActionController::Base
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def hello_world
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render :text => "#{params[:person]} says, Hello World!"
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end
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end
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The same can be done in a view to do a partial rendering:
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Let's see a greeting:
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<%= render_component :controller => "greeter", :action => "hello_world" %>
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It is also possible to specify the controller as a class constant, bypassing the inflector
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code to compute the controller class at runtime:
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<%= render_component :controller => GreeterController, :action => "hello_world" %>
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== When to use components
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Components should be used with care. They're significantly slower than simply splitting reusable parts into partials and
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conceptually more complicated. Don't use components as a way of separating concerns inside a single application. Instead,
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reserve components to those rare cases where you truly have reusable view and controller elements that can be employed
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across many applications at once.
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So to repeat: Components are a special-purpose approach that can often be replaced with better use of partials and filters.
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Copyright (c) 2007 David Heinemeier Hansson, released under the MIT license
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