[erlang-questions] [erlang-question][cowboy] Why got 415 unsupported media type when using POST method

[寂寂]

Dear All,

If I use GET method the REST API work properly, but when I change to POST, got 415 error

My code:

-export([init/2]).
-export([allowed_methods/2, content_types_provided/2]).
-export([to_json/2]).
init(Req, Opts) ->
    {cowboy_rest, Req, Opts}.

allowed_methods(Req, State) ->
    {[<<"POST">>], Req, State}.

content_types_provided(Req, State) ->
    {[
      {<<"application/json">>, to_json}
     ], Req, State}.

to_json(Req, State) ->
     .....

when I test the REST API I:
curl http://192.168.1.103:8080/cloud_init -v -XPOST -H"Content-Type: application/json" -d '{"client_id": "4342jltj3i"}'

got :
* Hostname was NOT found in DNS cache
*   Trying 192.168.1.103...
* Connected to 192.168.1.103 (192.168.1.103) port 8080 (#0)
> POST /cloudbox_init HTTP/1.1
> User-Agent: curl/7.37.1
> Host: 192.168.1.103:8080
> Accept: */*
> content-type: application/json
> Content-Length: 28
> 
* upload completely sent off: 28 out of 28 bytes
< HTTP/1.1 415 Unsupported Media Type
< connection: keep-alive
* Server Cowboy is not blacklisted
< server: Cowboy
< date: Fri, 10 Apr 2015 00:56:15 GMT
< content-length: 0
< content-type: application/json
< 
* Connection #0 to host 192.168.1.103 left intact
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