Extension points

phil/references-bundle

What an application implements, configures or relies on. References are phil/resource's.

Ports

`ReferenceCollector`

Phil\ReferencesBundle\Application\ReferenceCollector — finds what one kind of source links to. A service implementing it is tagged phil_references.collector by autoconfiguration. See Collectors and targets.

Method	Contract
`supports(object $source): bool`	Whether it reads this source
`sourceOf(object $source): ResourceReference`	The source's own reference, read before a deletion empties its identifier
`collect(object $source): iterable<Link>`	Each link, with the field it is in — a property, or a path into a JSON document

`ReferenceTarget`

Phil\ReferencesBundle\Application\ReferenceTarget — one kind of resource others use. A service implementing it is tagged phil_references.target by autoconfiguration. Without one, a kind is never refused a deletion nor checked for broken links.

Method	Contract
`kind(): string`	The kind it knows
`exists(string $id): bool`	Whether that resource still exists
`referenceOf(object $resource): ?ResourceReference`	The reference of an object of its kind, `null` for another object

`UsageRepository`

Phil\ReferencesBundle\Domain\Repository\UsageRepository — the table of usages, a public alias of DbalUsageRepository on connection. A store of the application's own keeps replace() writing only what changed and usagesOfAll() reading many targets at once.

Configuration

Option	What it extends
`connection`	The Doctrine connection that keeps the usages, and whose entities are tracked
`track_entities`	Whether the usages of Doctrine entities are kept up to date at each flush
`block_deletion`	Whether deleting an entity still used aborts the flush

Services

References — usagesOf(), assertUnused(), broken(), refresh(), forget() — is what the application calls: before a deletion, to show a message rather than a rolled-back flush, and for sources that are not Doctrine entities. See Usages.