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Routes for web framework builders

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Forward::Routes - restful routes for web framework developers


Instead of letting a web server like Apache decide which files to serve based on the provided URL, the whole work can be done by your framework using the Forward::Routes module.

Ruby on Rails and Perl's Mojolicious make use of routes. Forward::Routes, in contrast to that, tries to provide the same or even better functionality without the tight couplings with a full featured framework.

Think of routes as kind of simplified regular expressions! First of all, a bunch of routes is defined. Each route contains information on

  • what kind of URLs to match
  • what to do in case of a match

Finally, the request method and path of a users HTTP request are passed to search for a matching route.

1. Routes setup

Each route represents a specific URL or a bunch of URLs (if placeholders are used). The URL path pattern is defined via the add_route command. A route also contains information on what to do in case of a match. A common use case is to provide controller and action defaults, so the framework knows which controller method to execute in case of a match:

    # create a routes root object
    my $routes = Forward::Routes->new;

    # add a new route with a :city placeholder and controller and action defaults
    $routes->add_route('/towns/:city')->defaults(controller => 'World', action => 'cities');

2. Search for a matching route

After the setup has been done, the method and path of a current HTTP request can be passed to the routes root object to search for a matching route.

The match method returns an array ref of Forward::Routes::Match objects in case of a match, or undef if there is no match. Unless advanced techniques such as bridges are used, the array ref contains no more than one match object ($matches->[0]).

    # get request path and method (e.g. from a Plack::Request object)
    my $path   = $req->path_info;
    my $method = $req->method;

    # search routes
    my $matches = $routes->match($method => $path);

The search ends as soon as a matching route has been found. As a result, if there are multiple routes that might match, the route that has been defined first wins.

    # $matches is an array ref of Forward::Routes::Match objects
    my $matches = $routes->match(GET => '/towns/paris');

    # exactly one match object is returned:
    # $match is a Forward::Routes::Match object
    my $match = $matches->[0];

    # $match->params->{controller} is "World"
    # $match->params->{action}     is "cities"
    # $match->params->{city}       is "paris"

Controller and action parameters can be used by your framework to execute the desired controller method, while making default and placeholder values of the matching route available to that method for further use.

If the passed path and method do not match against a defined route, an undefined value is returned. Frameworks might render a 404 not found page in such cases.

    # $matches is undef
    my $matches = $routes->match(get => '/hello_world');

The match object holds two types of parameters:

  • default values of the matching route as defined earlier via the "defaults" method
  • placeholder values extracted from the passed URL path


Add new routes

The add_route method adds a new route to the parent route object (in simple use cases, to the routes root object) and returns the new route object.

The passed parameter is the URL path pattern of the new route object. The URL path pattern is kind of a simplified reqular expression for the path part of a URL and is transformed to a real regular expression internally. It is used later on to check whether the passed request path matches the route.

    $root = Forward::Routes->new;
    my $new_route = $root->add_route('foo/bar');

    my $m = $root->match(get => 'foo/bar');
    # $m->[0]->params is {}

    my $m = $r->match(get => 'foo/hello');
    # $m is undef;


Placeholders start with a colon and match everything except slashes. If the route matches against the passed request method and path, placeholder values can be retrieved from the returned match object.

    $r = Forward::Routes->new;

    $m = $r->match(get => 'hello/there');
    # $m->[0]->params is {foo => 'hello', bar => 'there'};

    $m = $r->match(get => 'hello/there/you');
    # $m is undef

Optional Placeholders

Placeholders can be marked as optional by surrounding them with brackets and a trailing question mark.

    $r = Forward::Routes->new;

    $m = $r->match(get => '2009');
    # $m->[0]->params is {year => 2009}

    $m = $r->match(get => '2009/12');
    # $m is undef

    $m = $r->match(get => '2009/12/10');
    # $m->[0]->params is {year => 2009, month => 12, day => 10}

    $r = Forward::Routes->new;

    $m = $r->match(get => 'hello/world');
    # $m->[0]->params is {}

    $m = $r->match(get => 'hello/world-paris');
    # $m->[0]->params is {city => 'paris'}


Placeholders have to be surrounded with brackets if more than one placeholder is put between slashes (grouping).

    $r = Forward::Routes->new;

    $m = $r->match(get => 'world/us-new_york');
    # $m->[0]->params is {country => 'us', cities => 'new_york'}


By default, placeholders match everything except slashes. The constraints method allows to make placeholders more restrictive. The first passed parameter is the name of the placeholder, the second parameter is a Perl regular expression.

    $r = Forward::Routes->new;

    # placeholder only matches integers
    $r->add_route('articles/:id')->constraints(id => qr/\d+/);
    $m = $r->match(get => 'articles/abc');
    # $m is undef
    $m = $r->match(get => 'articles/123');
    # $m->[0]->params is {id => 123}


The defaults method allows to add default values to a route. If the route matches against the passed request method and path, default values can be retrieved from the returned match object.

    $r = Forward::Routes->new;
      ->defaults(first_name => 'Kevin', last_name => 'Smith');

    $m = $r->match(get => 'articles');
    # $m->[0]->params is {first_name => 'Kevin', last_name => 'Smith'}

Optional Placeholders and Defaults

Placeholders are automatically filled with default values if the route would not match otherwise.

    $r = Forward::Routes->new;
    $r->add_route(':year(/:month)?/:day')->defaults(month => 1);

    $m = $r->match(get => '2009');
    # $m is undef

    $m = $r->match(get => '2009/12');
    # $m->[0]->params is {year => 2009, month => 1, day => 12}

    $m = $r->match(get => '2009/2/3');
    # $m->[0]->params is {year => 2009, month => 2, day => 3};

Shortcut for Action and Controller Defaults

The to method provides a shortcut for action and controller defaults.

    $r = Forward::Routes->new;


    # is a shortcut for
      ->defaults(controller => 'Foo', action => 'bar');

    $m = $r->match(get => 'articles');
    # $m->[0]->params is {controller => 'Foo', action => 'bar'}

Request Method Constraints

The via method sets the HTTP request method required for a route to match. If no method is set, the request method has no influence on the search for a matching route.

    $r = Forward::Routes->new;

    my $m = $r->match(get => 'logout');
    # $m is undef
    my $m = $r->match(post => 'logout');
    # $m->[0] is {}

All child routes inherit the method constraint of their parent, unless the method constraint of the child is overwritten.

Format Constraints

The format method restricts the allowed formats of a URL path. If the route matches against the passed request method and path, the format value can be retrieved from the returned match object.

    $r = Forward::Routes->new;

    $m = $r->match(get => 'hello/there.html');
    # $m->[0]->params is {foo => 'hello', bar => 'there', format => 'html'}

    $m = $r->match(get => 'hello/there.xml');
    # $m->[0]->params is {foo => 'hello', bar => 'there', format => 'xml'}

    $m = $r->match(get => 'hello/there.jpeg');
    # $m is undef

All child routes inherit the format constraint of their parent, unless the format constraint of the child is overwritten. For example, adding a format constraint to the route root object affects all child routes added via add_route.

    my $root = Forward::Routes->new->format('html');

    $m = $root->match(get => 'foo.html');
    # $m is undef;
    $m = $root->match(get => 'foo.xml');
    # $m->[0]->params is {format => 'xml'};

    $m = $root->match(get => 'baz.html');
    # $m->[0]->params is {format => 'html'};

    $m = $root->match(get => 'baz.xml');
    # $m is undef;

If no format constraint is added to a route and the route's parents also have no format constraints, there is also no format validation taking place. This might cause kind of unexpected behaviour when dealing with placeholders:

    $r = Forward::Routes->new;

    $m = $r->match(get => 'hello/there.html');
    # $m->[0]->params is {foo => 'hello', bar => 'there.html'}

If this is not what you want, an empty format constraint can be passed explicitly:

    $r = Forward::Routes->new->format('');

    $m = $r->match(get => 'hello/there.html');
    # $m->[0] is undef

    $m = $r->match(get => 'hello/there');
    # $m->[0]->params is {foo => 'hello', bar => 'there'}


Each route can get a name through the name method. Names are required to make routes reversible (see build_path).

    $r = Forward::Routes->new;

Path Building

Routes are reversible, i.e. paths can be generated through the build_path method. The first parameter is the name of the route. If the route consists of placeholders which are not optional, placeholder values have to be passed as well to generate the path, otherwise an exception is thrown. The build_path method returns a hash ref with the keys "method" and "path".

    $r = Forward::Routes->new;

    my $path = $r->build_path('hello', country => 'us', cities => 'new_york')
    # $path->{path}   is 'world/us-new_york';
    # $path->{method} is 'post';

Path building is useful to build tag helpers that can be used in templates. For example, a link_to helper might generate a link with the help of a route name: link_to('route_name', placeholder => 'value'). In contrast to hard coding the URL in templates, routes could be changed and all links in your templates would get adjusted automatically.


All methods can be chained.

    $r = Forward::Routes->new;
    my $articles = $r->add_route('articles/:id')
      ->defaults(first_name => 'foo', last_name => 'bar')
      ->constraints(id => qr/\d+/)

Nested Routes

New routes cannot only be added to the routes root object, but to any route. Building deep routes trees might result in performance gains in larger projects with many routes, as the amount of regular expression searches can be reduced this way.

    # nested routes
    $root = Forward::Routes->new;
    $nested1 = $root->add_route('foo1');

    $nested2 = $root->add_route('foo2');

    $m = $r->match(get => 'foo2/bar5');
    # 3 regular expression searches performed

    # alternative:
    $root = Forward::Routes->new;
    # 6 regular expression searches performed

Resource Routing

The add_resources method enables Rails like resource routing.

Please look at Forward::Guides::Routes::Resources for more in depth documentation on resourceful routes.

    $r = Forward::Routes->new;
    $r->add_resources('users', 'photos', 'tags');

    $m = $r->match(get => 'photos');
    # $m->[0]->params is {controller => 'Photos', action => 'index'}

    $m = $r->match(get => 'photos/1');
    # $m->[0]->params is {controller => 'Photos', action => 'show', id => 1}

    $m = $r->match(put => 'photos/1');
    # $m->[0]->params is {controller => 'Photos', action => 'update', id => 1}

    my $path = $r->build_path('photos_update', id => 987)
    # $path->{path} is 'photos/987'
    # $path->{method} is 'put'

Resource routing is quite flexible and offers many options for customization: Forward::Guides::Routes::ResourceCustomization

Please look at Forward::Guides::Routes::NestedResources for more in depth documentation on nested resources.


    $r = Forward::Routes->new;
    my $bridge = $r->bridge('admin')->to('Check#authentication');

    $m = $r->match(get => 'admin/foo');
    # $m->[0]->params is {controller => 'Check', action => 'authentication'}
    # $m->[1]->params is {controller => 'My', action => 'stuff'}






Copyright (C) 2011, ForwardEver

This program is free software, you can redistribute it and/or modify it under the terms of the Artistic License version 2.0.


Path matching and path building inspired by Viacheslav Tykhanovskyi's Router module

Concept of nested routes and bridges inspired by Sebastian Riedel's Mojolicious::Routes module

Concept of restful resources inspired by Ruby on Rails

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