Rescue Phoenix.MissingParamError and return json

Phoenix Forum Questions / Help
1

In my controller action i have two scrub_params clauses:

  plug :scrub_params, "account"
  plug :scrub_params, "studio"

When one of params is not present Phoenix raises Phoenix.MissingParamError. Is there any way to rescue this error and return some json message for user?

2 
plug MyApp.ScrubParams, "account"

defmodule MyApp.ScrubParams do
  def init(key), do: key
  def call(conn, key) do
    Phoenix.Controller.scrub_params(conn, key)
  rescue
    Phoenix.MissingParamError ->
      conn
      |> Plug.Conn.put_status(:bad_request)
      |> Phoenix.Controller.render(MyApp.ErrorView, "bad_params.json", key: key)
      |> Plug.Conn.halt()
  end
end
2 Likes
3

Shouldn’t there be a try somewhere? I’ve never seen rescue for def.

Heh, here it is https://hexdocs.pm/elixir/Kernel.html#def/2-rescue-catch-after.

1 Like
4

Function bodies support rescue, catch and after as SpecialForms.try/1 does

:slight_smile:

3 Likes
5

whaaaaaaaaaaaaaaaaaaaaaat

I can’t believe I’ve missed this!

2 Likes