Ally with an Elixir Problem

Question

I am using elli https://github.com/knutin/elli in my Elixir app.

An example code is given below. It is quite simple, every time it starts, I get only "Internal server error". I'm not sure what I'm doing wrong. Can anyone help?

defmodule Client.TestHttp do
  @behaviour :elli_handler

  def handle(_Req,_Args) do
    handle(:elli_request.method(Req), :elli_request.path(Req),Args)
  end

  def handle_event(_,_,_)do
    :ok
  end

  def handle(:GET,[],_)do
    {:ok, [], "OkGet"}
  end
end

This is how I perform

{:ok,pid}=:elli.start_link [callback: Client.TestHttp, port: 2020]

Answer 1

It looks like you haven't completely translated the Erlang code from the example and still use variables starting with an uppercase letter.

Change handle to:

  def handle(req, args) do
    handle(:elli_request.method(req), :elli_request.path(req), args)
  end

. Elixir snake_case CamelCase. (_), _var , , .

Req Args - Elixir, :

Req == :'Elixir.Req' # true

Answer 2

@Gazier ( , ), -. :

def handle(_Req,_Args) do
    handle(:elli_request.method(Req), :elli_request.path(Req),Args)
end

:elli_request.method _Req, :elli_request.path _Req _Args. , , ( ), :

 def handle(_Req,_Args) do
        handle(:elli_request.method(_Req), :elli_request.path(_Req),_Args)
    end

, .

Answer 3

, knutin/elli Elixir. , , elixir.

• @behaviour :elli_handler

  /. :

  # lib/elli_handler.ex
  defmodule ElliHandler do
    @behaviour :elli_handler
    alias :elli_request, as: Request
  
    def handle(req, args) do
      handle(Request.method(req), Request.path(req), req, args)
    end
  
    def handle(:GET, _, req, args) do
      # do something with the request.
      # e.g. you can use Request.get_arg/2 to fetch a query param
      say = Request.get_arg("say", req)
      # Return a tuple with 3 elements
      # status code, list of header tuples, response body
      {200, [], "echo, #{say}"}
    end
  
    # Here you can react to all kinds of events of the full connection/request/response cycle
    # You must implement this, otherwise elli wont function properly, as it evaluates
    # the return value of handle_event/3.
    def handle_event(event, args, config) do
      # Here would be a good point to handle logging.
      # IO.inspect([event, args, config])
      :ok
    end
  
  end
  

• , elli

  # lib/elli_supervisor.ex
  defmodule ElliSupervisor do
    use Supervisor
  
    def start_link(ref, options) do
      Supervisor.start_link(__MODULE__, options, name: ref)
    end
  
    def init(options) do
      children = [
        worker(:elli, [options], id: :elli_http_server)
      ]
      supervise(children, strategy: :one_for_one)
    end
  
    def shutdown(ref) do
      case Supervisor.terminate_child(ref, :elli_http_server) do
        :ok -> Supervisor.delete_child(ref, :elli_http_server)
        err -> err
      end
    end
  end
  
  # lib/app.ex
  defmodule App do
    use Application
  
    def start(_type, _args) do
      import Supervisor.Spec, warn: false
      # lets start our elli supervisor, setting its options
      # callback should be set to the elli handler that implements the elli_handler behaviour
      # port will be the port elli is listening on, defaults to 8080
      ElliSupervisor.start_link(__MODULE__, callback: ElliHandler, port: 3000)
    end
  
  end
  
  # in mix.exs
  def application do
    [
      mod: {App, []}
    ]
  end
  

• elli mix.exs

  mix get.deps, . mix run --no-halt , iex -S mix.

  # in mix.exs
  defp deps do
    [
      # elli is our web server layer
      {:elli, github: "knutin/elli"}
    ]
  end