Use Elixir plug for only some controller actions

Phoenix allows for a flexible request processing pipeline with plugs. Your controllers are basically plugs in the plug pipeline. You can specify plugs that will execute before your controller actions with the plug macro.

defmodule MyApp.ThingController do
  use MyApp.Web, :controller

  plug MyApp.InterestingPlug
end

You can also specify a guard for this macro that will only enable this plug to be run before certain actions:

plug MyApp.InterestingPlug when action in [:new, :create]