Roles plug inside of router phoenix

Question

At the moment I have a roles plug, that looks the following:

plug Roles, :role

It receives as the second parameter the specific role and the current user is obtained from the current token that is in use. I am using the plug inside of the controller module this way:

plug Roles, :manage_users when action in [:index, :show, :delete]

The problem with this is that I want to move all this logic to router.ex, to make it clear what the configs for controllers are.

From the documentation the default pipeline/1 and pipe_through/1 receive only an atom that is an identifier, so there is no way to pass parameters to my plug.

What would be the correct way to use this plug so that I can use it inside of router.ex?

Daniel Daniel · Accepted Answer · 2020-01-23T12:41:29

I ended up using some macro magic:

defmodule PlugUtils do

  defmacro __using__(_) do
    quote do
      import unquote(__MODULE__)
    end
  end

  defmacro param_pipe(pipe_name, plug_name, plug_params) do
    quote do
      pipeline unquote(pipe_name) do
        plug unquote(plug_name), unquote(plug_params)
      end

      pipe_through unquote(pipe_name)
    end
  end
end

Witch in turn can be used in router module the following way:

use PlugUtils
param_pipe :backups_upload, RolePlug, :upload_backup

The only downside to this approach is that I cannot point to the atoms of the controllers, since this plug is executed before the router plug, however by making separate scopes same thing can be achieved.

Roles plug inside of router phoenix

1 Answers