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cowboy/examples/rest_stream_response/src/toppage_handler.erl

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Add a REST example that streams its response
2013-02-10 13:54:51 -06:00
%% Feel free to use, reuse and abuse the code in this file.
%% @doc Streaming handler.
-module(toppage_handler).
-export([init/3]).
-export([rest_init/2]).
-export([content_types_provided/2]).
-export([streaming_csv/2]).
init(_Transport, _Req, _Table) ->
{upgrade, protocol, cowboy_rest}.
rest_init(Req, Table) ->
{ok, Req, Table}.
content_types_provided(Req, State) ->
{[
{{<<"text">>, <<"csv">>, []}, streaming_csv}
], Req, State}.
streaming_csv(Req, Table) ->
Breaking update of the cowboy_req interface Simplify the interface for most cowboy_req functions. They all return a single value except the four body reading functions. The reply functions now only return a Req value. Access functions do not return a Req anymore. Functions that used to cache results do not have a cache anymore. The interface for accessing query string and cookies has therefore been changed. There are now three query string functions: qs/1 provides access to the raw query string value; parse_qs/1 returns the query string as a list of key/values; match_qs/2 returns a map containing the values requested in the second argument, after applying constraints and default value. Similarly, there are two cookie functions: parse_cookies/1 and match_cookies/2. More match functions will be added in future commits. None of the functions return an error tuple anymore. It either works or crashes. Cowboy will attempt to provide an appropriate status code in the response of crashed handlers. As a result, the content decode function has its return value changed to a simple binary, and the body reading functions only return on success.
2014-09-23 16:43:29 +03:00
N = cowboy_req:binding(v1, Req, 1),
Add a REST example that streams its response
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MS = [{{'$1', '$2', '$3'}, [{'==', '$2', N}], ['$$']}],
Breaking update of the cowboy_req interface Simplify the interface for most cowboy_req functions. They all return a single value except the four body reading functions. The reply functions now only return a Req value. Access functions do not return a Req anymore. Functions that used to cache results do not have a cache anymore. The interface for accessing query string and cookies has therefore been changed. There are now three query string functions: qs/1 provides access to the raw query string value; parse_qs/1 returns the query string as a list of key/values; match_qs/2 returns a map containing the values requested in the second argument, after applying constraints and default value. Similarly, there are two cookie functions: parse_cookies/1 and match_cookies/2. More match functions will be added in future commits. None of the functions return an error tuple anymore. It either works or crashes. Cowboy will attempt to provide an appropriate status code in the response of crashed handlers. As a result, the content decode function has its return value changed to a simple binary, and the body reading functions only return on success.
2014-09-23 16:43:29 +03:00
{{stream, result_streamer(Table, MS)}, Req, Table}.
Add a REST example that streams its response
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result_streamer(Table, MS) ->
fun (Socket, Transport) ->
Convert the REST streaming example to a release
2013-09-08 19:50:31 +02:00
send_records(Socket, Transport, ets:select(Table, MS, 1))
Add a REST example that streams its response
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end.
send_records(Socket, Transport, {[Rec], Cont}) ->
timer:sleep(500),
send_line(Socket, Transport, Rec),
send_records(Socket, Transport, ets:select(Cont));
send_records(_Socket, _Transport, '$end_of_table') ->
ok.
send_line(Socket, Transport, [Key, V1, V2]) ->
Transport:send(Socket,
[Key, $,, integer_to_list(V1), $,, integer_to_list(V2), $\r, $\n]).
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