Cms: Move element/query recording out of the TemplateCaches service

[brandonkelly]

That way plugins could initiate their own template recorders, and use the resulting collections for their own purposes, unrelated to Craft's own caching system (for example, they could be used as Varnish dependencies).

[brandonkelly]

This is resolved for Craft 3.5. (885912438eb9c8929152552524d632bb0a6b514f)

• Element queries now register cache invalidation tags based on the parameters that are set on them

  https://github.com/craftcms/cms/blob/885912438eb9c8929152552524d632bb0a6b514f/src/elements/db/EntryQuery.php#L1009-L1023

• Element types now define the tags that should be invalidated when they are saved/deleted

  https://github.com/craftcms/cms/blob/885912438eb9c8929152552524d632bb0a6b514f/src/elements/Entry.php#L839-L852

• Anything that wants to start caching things that involve element queries can do so by calling craft\services\Elements::startCollectingCacheTags() before executing the queries, and stopCollectingCacheTags() afterwards, which will return a yii\caching\TagDependency object that can be used as a cache dependency.

We’re using this new system for template caches ({% cache %} tags) and GraphQL query caches. Here’s the GraphQL code, as that’s a simpler example, since it doesn’t have to worry about nested caches like template caches do:

https://github.com/craftcms/cms/blob/885912438eb9c8929152552524d632bb0a6b514f/src/services/Gql.php#L417-L440

https://github.com/craftcms/cms/blob/885912438eb9c8929152552524d632bb0a6b514f/src/services/Gql.php#L478-L488

[Mosnar]

@brandonkelly Great work! Just a heads-up, I was playing with this and if you don't create a query within the cache tag (for example, using the matched element (entry.title) instead, the cache is not automatically invalidated when the corresponding entry saves.

Does not clear on entry save:

{% cache %}
{{ entry.title }}
{% endcache %}

Does clear on entry save:

{% cache %}
    {% set entry = craft.entries.section('homepage').one() %}
    <h1>{{ entry.test }}</h1>
{% endcache %}

[brandonkelly]

@Mosnar I caught that yesterday as well. Should be fixed via decc3313bbbf63249bbf76903ed5f068fe3fd781.