Cowboy HTTP POST handlers

Question

I'm started learing Erlang. I want to write simple cowboy-based HTTP server, which can receive files sending via HTTP POST. So I create simple handler:

-module(handler).
-behaviour(cowboy_http_handler).
-export([init/3,handle/2,terminate/3]).

init({tcp, http}, Req, _Opts) ->
  {ok, Req, undefined_state}.

handle(Req, State) ->
  Body = <<"<h1>Test</h1>">>,
  {ok, Req2} = cowboy_req:reply(200, [], Body, Req),
  {ok, Req2, State}.

terminate(_Reason, _Req, _State) ->
  ok.

This code can handle GET request. But how can I process HTTP POST request?

Answer 1

Your code handles requests with any HTTP methods. If you want to handle particular HTTP request method you have to test the method name in callback handle/2. Here you can see a simple example:

handle(Req, State) ->
    {Method, Req2} = cowboy_req:method(Req),
    case Method of
        <<"POST">> ->
            Body = <<"<h1>This is a response for POST</h1>">>;
        <<"GET">> ->
            Body = <<"<h1>This is a response for GET</h1>">>;
        _ ->
            Body = <<"<h1>This is a response for other methods</h1>">>
    end,
    {ok, Req3} = cowboy_req:reply(200, [], Body, Req2),
    {ok, Req3, State}.

To get a content of POST request you can use function cowboy_req:body_qs/2 for example. There are other functions for handling body of HTTP requests in cowboy. Check the documentation and choose the way which is convenient for you.