Cowboy Rerouter

Cowboy Rerouter is a regular expression based router/dispatcher for Cowboy.

Styled after the Django URL dispatcher, it allows you to build complex URLs not possible with cowboy_router.

For the sake of simplicity it does not allow matching on hostnames, or contraint functions.

Currently it has no support for reversing URLs, but this may be added in the future.

Usage

1. Use cowboy_rerouter:compile/1 instead of cowboy_router:compile/1
2. Add {middlewares, [cowboy_rerouter, cowboy_handler]} to the ProtoOpts argument when starting the cowboy listener.

Your application:start/2 should look something like this:

start(_Type, _Args) ->
    Dispatch = cowboy_rerouter:compile([
        {"^/$", example_home_handler, []},
        {"^/about$", example_about_handler, []},
        {"^/user/(?P<id>\\d+)$", example_user_handler, []}
    ]),
    {ok, _} = cowboy:start_http(http, 100, [{port, 8080}], [
        {env, [{dispatch, Dispatch}]},
        {middlewares, [cowboy_rerouter, cowboy_handler]}
    ]),
    example_sup:start_link().

Route rules

Routes = [Route1, Route2, ... RouteN].

Each route contains a path matching regular-expression, the handler module, and the options that will be given to it on initialization.

Route = {Path, Handler, Opts}.
RouteA = {"^about/$", about_handler, []}.

You can include multiple routes under a prefix using a route_include route.

Route = {Path, [Route1, Route1, ... RouteN]}.
RouteP = {"^wheel/(?P<wheel_id>\\d+)/", [
    {"start$", wheel_start_handler, []},
    {"stop$", wheel_stop_handler, []},
    {"change$", wheel_change_handler, []}
]}.

This is functionally identical to

Routes = [
    {"^wheel/(?P<wheel_id>\\d+)/start$", wheel_start_handler, []},
    {"^wheel/(?P<wheel_id>\\d+)/stop$", wheel_stop_handler, []},
    {"^wheel/(?P<wheel_id>\\d+)/change$", wheel_change_handler, []},
    {"^wheel/(?P<wheel_id>)\\d+/start$", wheel_start_handler, []}
].

Match syntax

Bindings are captured with named groups, the syntax for named regular-expression groups is (?P<name>pattern), where name is the name of the group and pattern is some pattern to match. Bindings are retreived using cowboy_req:binding/{2,3}.