Locator Service

The locator service goal is to provides an abstraction layer for the different files and folders available across different sprinkles inside UserFrosting. In other words, it is a way of aggregating many search paths together. As you've seen in the previous chapters, each sprinkle can provides multiple resources and sprinkles can have the ability to overwrite a previous sprinkle resources. All of those resources, combined with the overwriting properties of a sprinkle is handled by the locator service. Templates and config files are a good example of those resources.

While the locator can be used to find files inside the sprinkles src/ directory, it can't be directly used to handle PHP Class Inheritance. The Dynamic Class Mapper needs to be used in such cases.

The locator can however be used where it's necessary to list PHP classes used to define objects or usable elements, such as migrations, seeds and Bakery commands related classes.

Streams and Locations

The locator uses the concept of Streams and Locations to represent directories and Sprinkles respectively. Each active sprinkle is registered as a Locator Location on boot. Several streams are registered on boot by the base system and the core sprinkle.

Two types of streams are available within the locator : shared and non-shared streams. The non-shared streams, or normal streams, represent a directory within the Sprinkles folder. Shared streams exists only in . Note that both type can coexist. For example, the bakery stream is defined twice, once shared and once non-shared. This allows to find resources (in this cases Bakery commands), inside each sprinkles as well as inside the system (app/system/) directory.

Default streams

The following streams are defined by default by UserFrosting :

Note that the assets streams will register different paths depending of the current Environment Mode. When in production mode, the compiled assets will be returned. Otherwise, the shared assets as well as the one from each sprinkles will be returned.

Using the locator

The locator provides many public methods for managing streams, locations and resources. But the most important tools provided by the locator is getting resources and listing resources. As stated earlier, this will allows you to find files and directories across multiple sprinkles, while respecting the sprinkle order or priority, without having to manually loop all sprinkles manually.

Getting resources

Whether you want to find a specific file or directory, the getResource and getResources methods will

Those two methods can be used to find paths for the specified URI. While getResource will return the top most file, getResources will return all the resources available for that URI, sorted by priority. For example:

$this->ci->locator->getResources('schema://default.json');

// RESULT :
/*
[
    'app/sprinkles/Core/schema/default.json',
    'app/sprinkles/Account/schema/default.json',
    'app/sprinkles/MySite/schema/default.json',
]
*/

$this->ci->locator->getResource('schema://default.json');

// RESULT :
// 'app/sprinkles/MySite/schema/default.json',

The locator will retuned an instance of the Resource object (or an array of objects). Theses objects can cast as string and will return the absolute path to the resource (file or directory). Further public methods can be used on the Resource object to get more information about the returned resource. For example, to return the sprinkle name where it was found :

$schema = $this->ci->locator->getResource('schema://default.json');
echo $schema->getLocation()->getName();

// RESULT :
// 'MySite'

Note theses methods can also work on directories URI :

$this->ci->locator->getResources('schema://foo');

// RESULT :
/*
[
    'app/sprinkles/Core/schema/foo',
    'app/sprinkles/Account/schema/foo',
    'app/sprinkles/MySite/schema/foo',
]
*/

Listing resources

All available resources in a given directory can be listed using the listResources method. This method will also returns the resources recursively, unlike getResources.

$resources = $this->ci->locator->listResources('schema://');

// RESULT :
/*
[
    'app/sprinkles/Core/schema/develop.json',
    'app/sprinkles/Core/schema/testing.json',
    'app/sprinkles/Account/schema/test/foo.json',
    'app/sprinkles/MySite/schema/default.json',
]
*/

If every sprinkle have a default.json file, only the top most version will be returned. To return all instances of every resources, the all flag can be set to true :

$resources = $this->ci->locator->listResources('schema://', true);

// RESULT :
/*
[
    'app/sprinkles/Core/schema/develop.json',
    'app/sprinkles/Core/schema/testing.json',
    'app/sprinkles/Core/schema/default.json',
    'app/sprinkles/Account/schema/default.json',
    'app/sprinkles/Account/schema/test/foo.json',
    'app/sprinkles/MySite/schema/default.json',
]
*/

Going further

For more information about the locator, you can refer to the detailed documentation, API reference and examples on the locator package repository.

Registering a custom stream

While the sprinkles stream can be used to access pretty much anything inside a sprinkle, sometimes it can be useful to create your own stream. Not only will it create a shorter URI, but you can also accommodate different use case, such as the usage of a shared stream or multiple search path.

To register a new stream, the locator service can't be extended. Fortunately, a new stream can be registered pretty much anywhere. You can register a new location from your sprinkle service provider, or even the sprinkle master class (eg. app/sprinkles/MySite/src/MySite.php).

This later approach is recommended as you won't have to touch a particular service to use the stream or create a service only for this purpose. However, if the stream is tied to a particular service, it could be easier to register the stream at the same time as this service. For example, if a foo service uses the bar stream and all access to the bar stream is done inside the foo service, then it make sense to register the bar stream inside the service.

To register a new service, the locator registerStream method can be used. The first argument is the stream name, the second the prefix and the third one the relative search path (from the root dir for shared stream, from each sprinkle dir for non-shared streams). The fourth parameter can be set to true to indicate a shared stream.

For example :

<?php

namespace UserFrosting\Sprinkle\MySite;

use UserFrosting\System\Sprinkle\Sprinkle;
use Psr\Container\ContainerInterface;

/**
 * Bootstrapper class for the `MySite` sprinkle.
 */
class MySite extends Sprinkle
{
    /**
     * Create a new Sprinkle object.
     *
     * @param ContainerInterface $ci The global container object, which holds all your services.
     */
    public function __construct(ContainerInterface $ci)
    {
        $this->ci = $ci;

        $this->registerStreams();
    }

    /**
     * Register sprinkle locator streams
     */
    protected function registerStreams()
    {
        /** @var \UserFrosting\UniformResourceLocator\ResourceLocator $locator */
        $locator = $this->ci->locator;

        // Register shared streams
        $locator->registerStream('storage', '', 'app/storage/', true);

        // Register sprinkle streams
        $locator->registerStream('storage', '', 'storage/');
        $locator->registerStream('orders', '', 'restaurant/orders/');

    }
}