Routing#

Routing is the process of mapping URL's to Controller and actions.

Routes are defined by setting the rules configuration array on Director. Typically you will add this configuration in a routes.yml file in your application or module's _config folder alongside your other configuration files.

# app/_config/routes.yml
---
Name: approutes
After:
  - '#rootroutes'
  - '#coreroutes'
---
SilverStripe\Control\Director:
  rules:
    'teams//$Action/$ID/$Name': 'App\Control\TeamController'
    'player/': 'App\Control\PlayerController'
    '': 'App\Control\HomeController'

The above declarations will instantiate a new controller with the given class name. If your controller needs some additional setup (e.g. it has constructor parameters or needs some method to be called before handling certain requests) you can set up a service with the injector and tell the Director to use that specific service.

SilverStripe\Control\Director:
  rules:
    'player/': '%$SpecialInjectedController'

See Dependency Injection for more information about the injector configuration syntax and how to define services.

Read the Configuration documentation for more information about the configuration API and syntax in general.

Alternative syntax#

The above example, and other examples in this section, show the controller class or service name as a single value in the array, with the routing rule that applies to it being the key.

If you want to be more explicit in your configuration declaration, you can instead set the value of the array to be another array, where the key is the word "Controller", and the value is again your controller class or service name.

SilverStripe\Control\Director:
  rules:
    'teams//$Action/$ID/$Name':
      Controller: 'App\Control\TeamController'
    'player/':
      Controller: '%$SpecialInjectedController'

Parameters#

SilverStripe\Control\Director:
  rules:
    'teams//$Action/$ID/$Name': 'App\Control\TeamController'

This route has defined that any URL beginning with teams/ should instantiate and be handled by a TeamController.

It also contains 3 parameters (or params for short). $Action, $ID and $Name. These are placeholders which will be filled when the user makes their request. Request parameters are available on the HTTPRequest object and can be pulled out from a controller using $this->getRequest()->param($name).

SilverStripe\Control\Director:
  rules:
    'teams': 'App\Control\TeamController'

Here is what those parameters would look like for certain requests

Accessing the /teams/ route:

$params = $this->getRequest()->params();

// returns the following array:
$params = [
    'Action' => null,
    'ID' => null,
    'Name' => null,
];

Accessing the /teams/players route:

$params = $this->getRequest()->params();

// returns the following array:
$params = [
    'Action' => 'players',
    'ID' => null,
    'Name' => null,
];

Accessing the /teams/players/1 route:

$params = $this->getRequest()->params();

// returns the following array:
$params = [
    'Action' => 'players',
    'ID' => 1,
    'Name' => null,
];

// You can also fetch one parameter at a time:
$id = $this->getRequest()->param('ID');

URL patterns#

The RequestHandler (of which Controller is a subclass) will parse all rules you specify against the following patterns. The most specific rule will be the one followed for the response.

The following is a very common URL handler syntax. For any URL that contains 'teams' this rule will match and hand over execution to the matching controller. The TeamsController is passed an optional action, id, and other id parameters to do any more decision making.

SilverStripe\Control\Director:
  rules:
    'teams//$Action/$ID/$OtherID': 'App\Control\TeamController'

# /teams/
# /teams/players/
# /teams/players/1
# /teams/players/1/13

This next example does the same matching as the previous example, any URL starting with teams will look at this rule but both $Action and $ID are required. Any requests to teams/ will result in a 404 error (or, if an appropriate looser routing rule exists, will match against that) rather than being handed off to the TeamController.

SilverStripe\Control\Director:
  rules:
    'teams//$Action!/$ID!': 'App\Control\TeamController'

Next we have a route that will any URL starting with /admin/help/, but don't include /help/ as part of the action (the shift point is set to start parsing variables and the appropriate controller action AFTER the //).

SilverStripe\Control\Director:
  rules:
    'admin/help//$Action/$ID': 'App\Control\AdminHelpController'

Wildcard URL patterns#

There are two wildcard patterns that can be used. $@ and $*. These parameters can only be used at the end of a URL pattern - anything in the pattern after one of these is ignored.

Inspired by bash variadic variable syntax there are two ways to capture all URL parameters without having to explicitly specify them in the URL rule.

Using $@ will split the URL into numbered parameters ($1, $2, ..., $n). For example:

SilverStripe\Control\Director:
  rules:
    'staff': 'App\Control\StaffController'

namespace App\Control;

use SilverStripe\Control\Controller;
use SilverStripe\Control\HTTPRequest;

class StaffController extends Controller
{
    private static $url_handlers = [
        '$@' => 'index',
    ];

    public function index(HTTPRequest $request)
    {
        // GET /staff/managers/bob
        // "managers"
        $request->latestParam('$1');
        // "bob"
        $request->latestParam('$2');
        // ["managers", "bob"]
        $request->latestParams();
    }
}

Alternatively, if access to the parameters is not required in this way then it is possible to use $* to match all URL parameters but not collect them in the same way:

namespace App\Control;

use SilverStripe\Control\Controller;
use SilverStripe\Control\HTTPRequest;

class StaffController extends Controller
{
    private static $url_handlers = [
        '$*' => 'index',
    ];

    public function index(HTTPRequest $request)
    {
        // GET /staff/managers/bob/hobbies
        // "managers/bob/hobbies"
        $request->remaining();

        // returns "managers", and removes that from the list of remaining params
        $nextParam = $request->shift();

        // returns ["bob", "hobbies"] and removes those from the list of remaining params
        $moreParams = $request->shift(2);
    }
}

URL handlers#

In previous examples the URLs were configured using the Director rules in the routes.yml file. Alternatively you can use this to provide just enough information for the Director to select your controller to handle the request, and specify the rest of the routing rules for your actions directly in your Controller class.

In this case, the routing rule only needs to provide enough information for the framework to choose the desired controller.

SilverStripe\Control\Director:
  rules:
    'teams': 'App\Control\TeamController'

The rest of the routing rule, which tells your controller which action should handle the request, is entered in the $url_handlers configuration array. This array is processed at runtime once the Controller has been matched.

This is useful when you want to provide one action to handle multiple route mappings. Say for instance we want to respond teams/coaches, and teams/staff to the one controller action payroll.

// app/src/Control/TeamController.php
namespace App\Control;

use SilverStripe\Control\Controller;

class TeamController extends Controller
{
    private static $url_segment = 'teams';

    private static $allowed_actions = [
        'payroll',
    ];

    private static $url_handlers = [
        'staff/$ID/$Name' => 'payroll',
        'coach/$ID/$Name' => 'payroll',
    ];

    // ...
}

The $url_handlers array uses the same syntax as the Director.rules configuration, except the value here is an action on the controller rather than the controller class itself. The patterns are relative to the main path that was used to match the controller in the first place.

Now let’s consider a more complex example, where using $url_handlers is mandatory. In this example, the URLs are of the form https://www.example.com/feed/go/, followed by 5 parameters.

The main routing rule to match the controller is simple:

SilverStripe\Control\Director:
  rules:
    'feed': 'App\Control\FeedController'

The PHP controller class specifies the URL pattern in $url_handlers. Notice that it defines 5 parameters.

namespace App\Control;

use SilverStripe\CMS\Controllers\ContentController;
use SilverStripe\Control\HTTPRequest;

class FeedController extends ContentController
{
    private static $url_segment = 'feed';

    private static $allowed_actions = [
        'go',
    ];

    private static $url_handlers = [
        'go/$UserName/$Timestamp/$OutputType/$DeleteMode' => 'go',
    ];

    public function go(HTTPRequest $request)
    {
        $user = $this->getUserByName($this->getRequest()->param('UserName'));
        /* more processing goes here */
    }
}

Root URL handlers#

SilverStripe\Control\Director:
  rules:
    'bread': 'App\Control\BreadAPIController'

In some cases, the Director rule covers the entire URL you intend to match, and you simply want the controller to respond to a 'root' request. This request will automatically direct to an index() method if it exists on the controller, but you can also set a custom method to use in $url_handlers with the '/' key:

namespace App\Control;

use SilverStripe\Control\Controller;

class BreadAPIController extends Controller
{
    private static $allowed_actions = [
        'getBreads',
        'createBread',
    ];

    private static $url_handlers = [
        'GET /' => 'getBreads',
        'POST /' => 'createBread',
    ];
}

Nested request handlers#

Nested RequestHandler routing is used extensively in the CMS and is used to create URL endpoints without YAML configuration. Nesting is done by returning a RequestHandler from an action method on another RequestHandler, usually a Controller.

RequestHandler is the base class for other classes that can handle HTTP requests such as Controller, FormRequestHandler (used by Form) and FormField.

How it works#

Director::handleRequest() begins the URL parsing process by parsing the start of the URL and workng out which request handler to use by looking in routes set in YAML config under Director.rules.

When a request handler matching the first portion of the URL is found, the handleRequest() method on the matched request handler is called. This passes control to the matched request handler and the next portion of the URL is processed.

From there regular request handling occurs and the URL will be checked to see if it matches $allowed_actions on the RequestHandler, possibly routed via $url_handlers. If an $allowed_action (i.e. method on the RequestHandler) is matched and that method returns a request handler, then control will be passed to this nested request handler and the next portion of the URL is processed.

Example of a nested request handler being returned in an action method#

Using the code below, navigating to the URL /one/two/hello will return a response with a body of "hello"

# app/_config/routes.yml
SilverStripe\Control\Director:
  rules:
    'one': 'App\Control\RequestHandlerOne'

// app/src/Control/RequestHandlerOne.php
namespace App\Control;

use SilverStripe\Control\Controller;
use SilverStripe\Control\HTTPRequest;

class RequestHandlerOne extends Controller
{
    // ...
    private static $allowed_actions = [
        'two',
    ];

    public function two(HTTPRequest $request)
    {
        return RequestHandlerTwo::create();
    }
}

// app/src/Control/RequestHandlerTwo.php
namespace App\Control;

use SilverStripe\Control\Controller;
use SilverStripe\Control\HTTPRequest;
use SilverStripe\Control\HTTPResponse;

class RequestHandlerTwo extends Controller
{
    // ...
    private static $allowed_actions = [
        'hello',
    ];

    public function hello(HTTPRequest $request)
    {
        return HTTPResponse::create()->setBody('hello');
    }
}

How RequestHandler and Form work together#

Form does not extend RequestHandler, instead it implements the HasRequestHandler interface which defines a method getRequestHandler(). Form::getRequestHandler() returns a FormRequestHandler which is a subclass of RequestHandler.

Request handlers and implementors of HasRequestHandler are treated the same because they will both end up calling handleRequest() on the appropriate request handler.

The FormRequestHandler.url_handlers configuration property includes an entry 'field/$FieldName!' => 'handleField' which allows it to handle requests to form fields on the form. FormRequestHandler::handleField() will find the form field matching $FieldName and return it. Control is then passed to the returned form field.

FormField extends RequestHandler, which means that form fields are able to handle HTTP requests and they have their own $allowed_actions configuration property. This allows form fields to define their own AJAX endpoints without having to rely on separately routed RequestHandler implementations.

Example of an AJAX form field that uses nested request handlers#

The AJAX request performed by the "Viewer groups" dropdown in asset admin has an endpoint of /admin/assets/fileEditForm/{FileID}/field/ViewerGroups/tree?format=json

That URL ends up passing the request through a series of nested request handlers, which is detailed in the steps below. Unless otherwise stated, the handleRequest() method is called on the class that has control. Control starts with Director.

1. admin matches a rule in the Director.rules YAML configuration property and control is passed to AdminRootController
2. assets matches the AssetAdmin.url_segment property that has a value of assets and control is passed to AssetAdmin
3. fileEditForm/{FileID} matches 'fileEditForm/$ID' => 'fileEditForm' in AssetAdmin.url_handlers so the AssetAdmin::fileEditForm() method is called
4. AssetAdmin::fileEditForm() returns a Form scaffolded for the File matching the ID and control is passed to the returned Form
5. Form::getRequestHandler() will be called on the Form and control is passed to the FormRequestHandler that is returned
6. field/ViewerGroups matches 'field/$FieldName!' => 'handleField' in FormRequestHandler.url_handlers, so FormRequestHandler::handleField() is called
7. FormRequestHandler::handleField() finds the ViewerGroups field in the Form which is a TreeMultiselectField that extends TreeDropdownField and control is passed to the field
8. tree matches tree in TreeDropdownField.allowed_actions, so TreeDropdownField::tree() is called
9. TreeDropdownField::tree() returns an HTTPResponse with its body containing JSON

Related lessons#

• Creating filtered views
• Controller actions / DataObjects as pages

Links#

• Controller API documentation
• Director API documentation
• Example routes: framework
• Example routes: CMS