repository.md

Repository

ProjectionRepositoryInterface

The projection item is projected through a repository which implements ProjectionRepositoryInterface interface.

This holds methods to get, add and delete the projections. The methods are used by passing a projection item object.

interface ProjectionRepositoryInterface
{
    public function add(ProjectionItemInterface $item): void;

    public function addDeferred(ProjectionItemInterface $item): void;

    public function flush(): void;

    public function get(ProjectionItemInterface $item): ?ProjectionItemInterface;

    public function delete(ProjectionItemInterface $item): void;

    public function deleteByTags(Tags $tags): void;
}

• add() method immediately projects the item.
• addDeferred() method sets items to be projected, but they are only projected when flush() is called.
• get() method gets a projected item. If it is not projected, then null is returned.
• delete() method deletes item from projection
• deleteByTags() method deletes all projected items that have at least one of the tags passed as argument

Implementations

SymfonyCacheProjectionRepository

This class implements a repository, which projects the items using Symfony's Tag Aware Cache Pool component.

This means that then when projecting an item, if tags are available for it, the item will also include tags and those items can be invalidated in the cache with the deleteByTags method.

Psr6CacheProjectionRepository

This class implements a repository, which projects the items using any PSR-6 Cache implementation.

Unlike the SymfonyCacheProjectionRepository, no support for tags is available (they will be ignored when projecting) and calling deleteByTags method will throw an exception.

If your PSR-6 implementation supports tags then is up to you to create an implementation of ProjectionRepositoryInterface and make the required changes.

You expand AbstractProjectionRepository and do the required changes to deleteByTags and createCacheItem methods. See SymfonyCacheProjectionRepository which does just that.