cases.ex

defmodule Api.Resource.Cases do
  use PoeApi.Resource
  
  let service = Resource.param(:service)

  let cases = apply(service, :get_all, [Input.get])

  hyper do
    action do
      %{
        "count" => length(cases),
        "collection" => for item <- cases do
          link_to(Resource.param(:read), item: item["sys_id"])
          |> ^Map.merge(item)
        end,
        "create" => link_to(Resource.param(:create))
      }
    end
  end
end

router.ex

defmodule Router do
  get "/change_requests",  {Api.Resource.Cases, ChangeRequests}, service: Api.Service.ChangeRequests,
                                                                 read: {Api.Resource.Cases, ChangeRequests.Read},
                                                                 create: {Api.Resource.Cases, ChangeRequests.Create}
  get "/service_requests",  {Api.Resource.Cases, ServiceRequests}, service: Api.Service.ServiceRequests,
                                                                   read: {Api.Resource.Cases, ServiceRequests.Read},
                                                                   create: {Api.Resource.Cases, ServiceRequests.Create}
end

λ : make
Erlang/OTP 18 [erts-7.2.1] [source] [64-bit] [smp:8:8] [async-threads:10] [hipe] [kernel-poll:false] [dtrace]

Compiled lib/api.ex
lib/api/http.ex:1: warning: the underscored variable "_path" is used after being set. A leading underscore indicates that the value of the variable should be ignored. If this is intended please rename the variable to remove the underscore
Compiled lib/api/http.ex
Compiled lib/api/resource/root.ex

== Compilation error on file lib/api/resource/cases.ex ==
** (Protocol.UndefinedError) protocol String.Chars not implemented for Elixir.Mazurka.Resource.Resource.get_param(Elixir.Mazurka.Resource.Resource.resource_params(), :service)
    (elixir) lib/string/chars.ex:3: String.Chars.impl_for!/1
    (elixir) lib/string/chars.ex:17: String.Chars.to_string/1
    lib/etude/utils.ex:98: Etude.Utils.debug_call/4
    lib/etude/node/call.ex:73: Etude.Node.Etude.Node.Call.compile_exec/4
    lib/etude/node/call.ex:59: Etude.Node.Etude.Node.Call.compile/2
    lib/etude/children.ex:11: anonymous fn/3 in Etude.Children.compile/2
    (elixir) lib/enum.ex:1473: Enum."-reduce/3-lists^foldl/2-0-"/3
    lib/etude/node/assign.ex:21: Etude.Node.Etude.Node.Assign.compile/2

make: *** [start] Error 1