Where can I put my Plugs and then use them from different controllers in my Phoenix app?

Question

I'm creating my first Elixir-Phoenix app. I've written a few plugs that I want to use in multiple controllers, right now there is a lot of code duplication since the Plug code is being repeated in all of my controllers.

My question is, is there a file where I can put all of my Plugs and then access and use them from different controllers?

# somefile to define my plugs  defp load_subject(conn, _) do     subject = Subject |> Repo.get conn.params["subject_id"]      assign(conn, :subject, subject) end  defp load_topic(conn, _) do     topic = Topic |> Repo.get conn.params["topic_id"]      conn |> assign :topic, topic end 

Then use them in my controllers:

# First Controller defmodule MyApp.FirstController do     use MyApp.Web, :controller      plug :load_subject     plug :load_topic     plug :action      def some_action(conn, _) do         # do something     end      def another_action(conn, _) do         # do some other thing     end end  # Second Controller defmodule MyApp.SecondController do     use MyApp.Web, :controller      plug :load_subject     plug :load_topic     plug :action      def lame_action(conn, _) do         # do something     end      def cool_action(conn, _) do         # do some other thing     end end 

Answer 1

You can define the plugs in any module as public functions:

defmodule MyApp.Loaders do   import Plug.Conn    def load_subject(conn, _) do     subject = Subject |> Repo.get conn.params["subject_id"]     assign(conn, :subject, subject)   end    def load_topic(conn, _) do     topic = Topic |> Repo.get conn.params["topic_id"]     conn |> assign :topic, topic   end end 

Now you can import it in your controllers and use the plugs:

defmodule MyApp.Controller do   use MyApp.Web, :controller   import MyApp.Loaders    plug :load_subject   plug :load_topic   plug :action    ... end 

Alternatively, you can also create a pipeline in your router:

import MyApp.Loaders  pipeline :with_subject_and_topic do   plug :load_subject   plug :load_topic end 

And then pipe_through it in the relevant scopes.