Yaws REST API sample

gistfile1.erl

-module(rest).

-include("/opt/local/lib/erlang/lib/stdlib-1.18.2/include/qlc.hrl").
-include("/opt/local/lib/yaws/include/yaws_api.hrl").

-export([out/1, addAirport/4, handle/2 ]).

-define(RECORD_TYPE, airport).
-define(RECORD_KEY_FIELD, code).

-record(?RECORD_TYPE, {?RECORD_KEY_FIELD, city, country, name}).


out(Arg) ->
    Method = method(Arg),
    io:format("~p:~p ~p Request ~n", [?MODULE, ?LINE, Method]),
    handle(Method, Arg).

method(Arg) ->
    Rec = Arg#arg.req,
    Rec#http_request.method.


convert_to_Json(Lines) ->
    Data = [{obj,
	     [{airport, Line#?RECORD_TYPE.code},
	      {city,    Line#?RECORD_TYPE.city},
	      {country, Line#?RECORD_TYPE.country},
	      {name,    Line#?RECORD_TYPE.name}]}
	    || Line <- Lines],
    JsonData = {obj, [{data, Data}]},
    rfc4627:encode(JsonData).

addAirport(Code, City, Country, Name) ->
    NewRec = #?RECORD_TYPE{
		 ?RECORD_KEY_FIELD = Code,
		 city = City,
		 country = Country,
		 name = Name},
    io:format("~p:~p Adding Airport ~p~n", [?MODULE, ?LINE, NewRec]),
    Add = fun() ->
		  mnesia:write(NewRec)
	  end,
    {atomic, _Rec} = mnesia:transaction(Add),
    NewRec.

handle('GET', _Arg) ->
    io:format("~n ~p:~p GET Request ~n", [?MODULE, ?LINE]),
    Records = do(qlc:q([X || X <- mnesia:table(?RECORD_TYPE)])),
    Json = convert_to_Json(Records),
    io:format("~n ~p:~p GET Request Response ~p ~n", [?MODULE, ?LINE, Json]),
    {html, Json};

handle('POST', Arg) ->
    {ok, Json, _} = rfc4627:decode(Arg#arg.clidata),
    io:format("~n~p:~p POST request ~p~n", [?MODULE, ?LINE, Json]),
    Airport = rfc4627:get_field(Json, "airport", <<>>),
    City = rfc4627:get_field(Json, "city", <<>>),
    Country = rfc4627:get_field(Json, "country", <<>>),
    Name = rfc4627:get_field(Json, "country", <<>>),
    _Status = addAirport(Airport, City, Country, Name),
    [{status, 201}, {html, Arg#arg.clidata}];

handle('PUT', Arg) ->
    [IndexValue,_] = string:tokens(Arg#arg.pathinfo),
    {ok, Json, _} = rfc4627:decode(Arg#arg.clidata),
    io:format("~p:~p PUT request ~p ~p~n", [?MODULE, ?LINE, IndexValue, Json]),
    Airport = rfc4627:get_field(Json, "airport", <<>>),
    City = rfc4627:get_field(Json, "city", <<>>),
    Country = rfc4627:get_field(Json, "country", <<>>),
    Name = rfc4627:get_field(Json, "country", <<>>),

    NewRec = #?RECORD_TYPE{
		 ?RECORD_KEY_FIELD = Airport,
		 city = City,
		 country = Country,
		 name = Name},
    
    io:format("~p:~p Renaming ~p", [?MODULE, ?LINE, NewRec]),
    ChangeName = fun() ->
			 mnesia:delete({?RECORD_KEY_FIELD, IndexValue}),
			 mnesia:write(NewRec)
		 end,
    {atomic, _Rec} = mnesia:transaction(ChangeName),
    [{status, 200}, 
     {html, IndexValue}];

handle('DELETE', Arg) ->
    [IndexValue, _] = string:tokens(Arg#arg.pathinfo),
    io:format("~p:~p DELETE request ~p", [?MODULE, ?LINE, IndexValue]),
    Delete = fun() ->
		     mnesia:delete({?RECORD_KEY_FIELD, IndexValue})
	     end,
    Resp = mnesia:transaction(Delete),
    case Resp of
	{atomic, ok} ->
	    [{status, 204}];
	{_, Error} ->
	    io:format("~p:~p Error ~p ", [?MODULE, ?LINE, Error]),
	    [{status, 400}, {html, Error}]
    end;

handle(Method,_) ->
    [{error, "Unknown method " ++ Method },
     {status, 405},
     {header, "Allow: GET, HEAD, POST, PUT, DELETE"}
     ].

do(Q) ->
    F = fun() ->
		qlc:e(Q)
	end,
    {atomic, Value} = mnesia:transaction(F),
    Value.