I'm thinking of using Google's Workbox to pre-cache a bunch of files, and I've been scratching my head as to how to generate unique hashes for files when they change. Something like this:

      url: '/',
      revision: '383676',
      url: '/about',
      revision: 213142,
      town: '/location',
      revision: 742125,

Ideally the revision number would change when the entry or related entries included in the page are changed/saved. I got this working but I'm not sure how to get related content to clear the cache:

// service-worker.js

{%- cache using key 'abc' -%}
      url: {{ craft.entries.id(64).one.uri }},
      revision: {{ random(100000, 999999) }},
{%- endcache -%}

This seems to work when said entry is saved, but I'm not sure how to deal with a related entry being saved. I'm also not sure this is the most performant way to go.

1 Answer 1


So you shouldn't try to come up with a hashed file naming scheme for busting the cache; instead use one of Workbox's Strategies -- I think a great pattern for what you're trying to do is Stale While Revalidate

TL;DR Workbox has strategies for doing what you're trying to do.

  • Thanks Andrew, but this is what I'm wondering: does re-validating mean going back to the server and requesting the page (and querying the DB) even if the page hasn't changed? I'd imagine that with a manifest, if the hashed file hasn't changed, then the SW would simply serve from the cache and stay away from the server until instructed to do so.
    – Paul
    Jun 15, 2019 at 3:17
  • There are many strategies you can adopt... my point is really that Workbox can handle this for you, you're not going to need template logic. Jun 24, 2019 at 18:58
  • It took me a while to wrap my head around all this, but the precache manifest is useful primarily for static assets (js, css...). In my case, stale-while-revalidate is probably the way to go for content, provided I can workout how to refresh the page when new content is available.
    – Paul
    Jun 26, 2019 at 1:22

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