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cowboy/examples/echo_get/src/toppage_handler.erl

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Add a GET echo example
2012-07-21 21:46:21 +02:00
%% Feel free to use, reuse and abuse the code in this file.
%% @doc GET echo handler.
-module(toppage_handler).
Unify the init and terminate callbacks This set of changes is the first step to simplify the writing of handlers, by removing some extraneous callbacks and making others optional. init/3 is now init/2, its first argument being removed. rest_init/2 and rest_terminate/2 have been removed. websocket_init/3 and websocket_terminate/3 have been removed. terminate/3 is now optional. It is called regardless of the type of handler, including rest and websocket. The return value of init/2 changed. It now returns {Mod, Req, Opts} with Mod being either one of the four handler type or a custom module. It can also return extra timeout and hibernate options. The signature for sub protocols has changed, they now receive these extra timeout and hibernate options. Loop handlers are now implemented in cowboy_long_polling, and will be renamed throughout the project in a future commit.
2014-09-26 15:58:44 +03:00
-export([init/2]).
Add a GET echo example
2012-07-21 21:46:21 +02:00
Unify the init and terminate callbacks This set of changes is the first step to simplify the writing of handlers, by removing some extraneous callbacks and making others optional. init/3 is now init/2, its first argument being removed. rest_init/2 and rest_terminate/2 have been removed. websocket_init/3 and websocket_terminate/3 have been removed. terminate/3 is now optional. It is called regardless of the type of handler, including rest and websocket. The return value of init/2 changed. It now returns {Mod, Req, Opts} with Mod being either one of the four handler type or a custom module. It can also return extra timeout and hibernate options. The signature for sub protocols has changed, they now receive these extra timeout and hibernate options. Loop handlers are now implemented in cowboy_long_polling, and will be renamed throughout the project in a future commit.
2014-09-26 15:58:44 +03:00
init(Req, Opts) ->
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
Method = cowboy_req:method(Req),
Reverse the order of arguments of match_* functions Wasn't following the same order as the rest of the module.
2014-10-04 13:21:16 +03:00
#{echo := Echo} = cowboy_req:match_qs([echo], Req),
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
Req2 = echo(Method, Echo, Req),
Improve handler interface and documentation This change simplifies a little more the sub protocols mechanism. Aliases have been removed. The renaming of loop handlers as long polling handlers has been reverted. Plain HTTP handlers now simply do their work in the init/2 callback. There is no specific code for them. Loop handlers now follow the same return value as Websocket, they use ok to continue and shutdown to stop. Terminate reasons for all handler types have been documented. The terminate callback is now appropriately called in all cases (or should be). Behaviors for all handler types have been moved in the module that implement them. This means that cowboy_handler replaces the cowboy_http_handler behavior, and similarly cowboy_loop replaces cowboy_loop_handler, cowboy_websocket replaces cowboy_websocket_handler. Finally cowboy_rest now has the start of a behavior in it and will have the full list of optional callbacks defined once Erlang 18.0 gets released. The guide has been reorganized and should be easier to follow.
2014-09-30 20:12:13 +03:00
{ok, Req2, Opts}.
Add a GET echo example
2012-07-21 21:46:21 +02:00
Don't use decode_packet/3 for parsing the request-line First step in making all methods and header names binaries to get rid of many inconsistencies caused by decode_packet/3. Methods are all binary now. Note that since they are case sensitive, the usual methods become <<"GET">>, <<"POST">> and so on.
2012-09-20 06:22:51 +02:00
echo(<<"GET">>, undefined, Req) ->
Rename cowboy_http_req to cowboy_req
2012-08-27 13:28:57 +02:00
cowboy_req:reply(400, [], <<"Missing echo parameter.">>, Req);
Don't use decode_packet/3 for parsing the request-line First step in making all methods and header names binaries to get rid of many inconsistencies caused by decode_packet/3. Methods are all binary now. Note that since they are case sensitive, the usual methods become <<"GET">>, <<"POST">> and so on.
2012-09-20 06:22:51 +02:00
echo(<<"GET">>, Echo, Req) ->
Fix echo_get example
2016-06-08 20:18:09 +02:00
cowboy_req:reply(200, #{
<<"content-type">> => <<"text/plain; charset=utf-8">>
}, Echo, Req);
Add a GET echo example
2012-07-21 21:46:21 +02:00
echo(_, _, Req) ->
%% Method not allowed.
Rename cowboy_http_req to cowboy_req
2012-08-27 13:28:57 +02:00
cowboy_req:reply(405, Req).
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