Access result of Elixir Plug.Parsers.JSON

Question

I am writing a small http server using Elixir Plug and having some trouble understanding how its parser works. I cannot figure out how to access the result of the parser in my router. I currently have

...
plug Plug.Parsers, parsers: [:json],
                json_decoder: Poison
plug :match
plug :dispatch
forward "/admin" , to: VoucherSite.Admin.AdminRouter
...

And in the admin router I want to access the parsed result from the Parser called above

put "/user" do
  ...access result here...
  respond(conn, {:ok, ""})
end

It feels like I am missing something obvious but all I have access to is conn which is the connection so no idea how to get the parsed body from the request.

You can reach decoded json with `conn.params` – Mesut Tasci Oct 26 '18 at 00:31 — Mesut Tasci, Oct 26 '18 at 00:31

score 0 · Accepted Answer · answered Apr 03 '17 at 14:44

Plug is a behaviour, having 2 callbacks: init/1 and call/2. The latter receives a Plug.Conn struct and returns possibly modified Plug.Conn struct. That allows to chain plugs.

%Plug.Conn{assigns} is intended to be used to update the map between calls to different plugs.

Plug.Conn implements the Inspect algebra out of the box, so just do:

Logger.debug inspect(conn)

somewhere and you’ll see where the parser stores the body (I would bet it’s some key in the assigns map.)

Access result of Elixir Plug.Parsers.JSON

1 Answers1