How to access `conn` from different module?

Questions / Help
1

Hi friends, How can we get conn object in a different module (in my case resolution function of absinthe) ?
I want to get the ip by conn.remote_ip property of conn. But I’m not able to get the conn :grimacing:

2

Show your code. Propably you didn’t use plug properly. You should use plug to intercept the conn or just pass conn explicitly to your function in the controller’s action.

3 
defmodule MyApp.Schema do
  use Absinthe.Schema
  import Plug.conn
  ...
  ...
  ...
  field :tracking_ip, :string do
    arg: params
   resolve fn {%{context: %{current_user: current_user}} -> 
      IO.inspect conn
   end
end

I want to fetch the ip form conn!

4

import Plug.Conn would only import the functions inside the Plug.Conn module, not the conn struct from a request.

What you probably want to do is create a “context” plug like here where you can add the ip address to the returned context, such that your resolve function would become

resolve fn _, %{context: %{current_user: current_user, remote_ip: remote_ip}} -> 
  ...
end

The context plug would probably look like this

defmodule YourAppName.Web.Context do
  @behaviour Plug
  import Plug.Conn

  def init(opts) do
    opts
  end

  def call(conn, _opts) do
    case build_context(conn) do
      {:ok, context} ->
        put_private(conn, :absinthe, %{context: context})
      {:error, reason} ->
        conn
        |> send_resp(403, reason)
        |> halt()
      _ ->
        conn
        |> send_resp(400, "Bad Request")
        |> halt()
    end
  end


  # Return the current user context based on the authorization header
  # and remote ip address
  defp build_context(%{req_readers: req_readers, remote_ip: remote_ip}) do
    with "Bearer " <> token <- :proplists.get_value("authorization", req_readers),
         {:ok, current_user} <- authorize(token) do
      {:ok, %{current_user: current_user, remote_ip: remote_ip}}
    end
  end
  
  defp authorize(token) do
    # ... your auth logic
  end
end

Note that remote_ip might be “wrong” if you are behind a load balancer.

2 Likes