Repeated calls to cache.updateQuery do not perform cumulative effects

[codazzo]

Hi! As I mentioned in #1068 (reply in thread) I'm trying to use urql for a scenario where I expect users of a native app to be offline for long enough stretches of time wherein they can perform a number of mutations, each of which would create a "Recommendation" entity.

For this I'm using a custom updater

offlineExchange({
    storage, // <--- I created this using AsyncStorage
    schema,
    updates: {
        Mutation: {
            createRecommendation: (result, args, cache, info) => {
                const recommendation = .... // builds recommendation from args
                const fieldId = ... // gets field Id from args

                cache.updateQuery({ query: QUERY_RECOMMENDATIONS, variables: { fieldId } }, (data) => {
                    data.recommendations.push(recommendation);
                    return data;
                });
            },
        },
    },
    optimistic: {
        createRecommendation: ... // creates a Recommendation entry
    }
});

This works the first time: even if the device is disconnected, I can see the newly-created recommendation if I use the client to query QUERY_RECOMMENDATIONS. Upon following attempts though, keeping the device offline, data.recommendations in the updater function passed to cache.updateQuery does not include any recommendation that was previously created while the device was offline. As a consequence, if I query QUERY_RECOMMENDATIONS after the mutation, I always only see only the latest recommendation that was created offline (plus all of the recommendations that were created while the device was connected).

Is there a way these offline updates can be cumulative, i.e. I could create one recommendation after the other and see them all while the device is offline?

Thanks! 🙏

[kitten]

That's pretty odd! I'm trying to think of what could be causing this, because optimistic updates should always allow you to cumulatively add to a list already. So let's debug this and maybe I can write a new test for our test suite to make sure that this is indeed broken and then subsequently fix it if it's indeed buggy.

So on the second optimistic createRecommendation call of updates.Mutation.createRecommendation, have you verified that it's indeed called, that the list is missing the last recommendation, or whether any other weird behaviour already occurs there?

You said that it's called but lacking the previous recommendation; that's all while the device was offline and only optimistic updates were made, right?

[kitten]

Alright, I've got a fix ready for this. As it turned out we did this on purpose and I'm not sure anymore why we deemed cumulative optimistic updates unsafe, because they shouldn't be. So if you'd like to test these changes I'd be super grateful 🙏 #1074

You can test out this set of changes by using the package that CodeSandbox CI builds for us. It'll give you a link to a temporary package once it's done.

[codazzo]

That's amazing 😍 I will test this right away. I've been running urql via yarn link for a while anyway to poke around the source so it should just be a fetch and checkout away. Will report!

[kitten]

Ok, note that this is a Graphcache issue, so it's not related to urql. Also btw, there may be some issues with duplicate dependencies when you yarn link so make sure you're not seeing weird unrelated issues 😅 Anyway, to test this out you can also install Graphcache in your package.json from https://pkg.csb.dev/FormidableLabs/urql/commit/16c0f581/@urql/exchange-graphcache. So if you set the @urql/exchange-graphcache version to that, you'll get this fix.

[codazzo]

I can confirm that the updates were applied cumulatively and the mutations were performed when the device got back online. Thanks for the stellar support!

[kitten]

This has also just been released! Can't wait to hear more about how you get on! 🙌 https://github.com/FormidableLabs/urql/releases/tag/%40urql%2Fexchange-auth%400.1.1