SolidJS•4w ago

createSignal equals: false on mutable object value

Hi guys, I have a resource source signal with { equals: false } that does not trigger fetching unless I wrap and deep copy the object literal value in the source param. The value itself is a propety of an instance wrapped with createMutable, which I suspect is at the crux of this. But why? I though equals: true would guarantee a truthy source signal on setting?

const muatable = createMutable(myClassInstance)
[...]
const [onSaveSignal, setSaveSignal] = createSignal(mutable.data, { equals: false })
[...]
createResource(
   onSaveSignal,
   (sigObjValue) => {
     fetch...
   }
);

const muatable = createMutable(myClassInstance)
[...]
const [onSaveSignal, setSaveSignal] = createSignal(mutable.data, { equals: false })
[...]
createResource(
   onSaveSignal,
   (sigObjValue) => {
     fetch...
   }
);

Above not working, below working.

createResource(
   () => deepCopy(onSaveSignal()),
   (sigObjValue) => {
     fetch...
   }
);

createResource(
   () => deepCopy(onSaveSignal()),
   (sigObjValue) => {
     fetch...
   }
);

shallow structuredClone also fails.

17 Replies

REEEEE•4w ago

Signals definitions aren't reactive meaning that createSignal(mutable.data) won't be updated with the latest mutable.data when it changes

FlemmingOP•4w ago

Hmm, still the isgnal triggers as I can debug from within { equals: () => { ... })

REEEEE•4w ago

If you're writing to the signal somewhere, it will still fire the equals check

FlemmingOP•4w ago

Yes, that is the case. Therefore I assumed { equals: false } would work.

REEEEE•4w ago

How are you writing to the signal?

FlemmingOP•4w ago

setSaveSignal(mutable.data)

REEEEE•4w ago

Hmm Looks like createResource will memo the source signals

FlemmingOP•4w ago

Sth along those lines would explain it, but reading the documentation, that is excatly what { equals: false } should circumvent?

REEEEE•4w ago

maybe a small change that could work is to do () => ({data: onSaveSignal()}) The memo has it's own equals handling By default it checks via ===

FlemmingOP•4w ago

I tested now, just give me a few sec to double check that I have doen it right... Yes that works with { equals: false }

  const [onFilterListings, setFilterListings] =
    createSignal<FilterSchemaType | null>(null, {
      equals: false
    });

  const [filteredListings, { mutate: mutateFilteredListings }] = createResource(
    // Need a deep-copy for sourcesignal to diff on data-content
    () => ({ filters: onFilterListings() }),
    async ({ filters }) => {
      console.log('onFilterListings', { filters });
      const listings = await listingService.loadListingsByFilters(filters!);
      return listings;
    },
  );

  const [onFilterListings, setFilterListings] =
    createSignal<FilterSchemaType | null>(null, {
      equals: false
    });

  const [filteredListings, { mutate: mutateFilteredListings }] = createResource(
    // Need a deep-copy for sourcesignal to diff on data-content
    () => ({ filters: onFilterListings() }),
    async ({ filters }) => {
      console.log('onFilterListings', { filters });
      const listings = await listingService.loadListingsByFilters(filters!);
      return listings;
    },
  );

But, this should also work without { equals: false } ? Due to shallow comparison?

REEEEE•4w ago

yeah it should but you have to make sure when you set setFilterListings it's a new obj otherwise the signals default equality === will pass

FlemmingOP•4w ago

Hmm, I see what you mean, but then the case is that { equals: false } is a bit misleading? It swithches from deep (?) to shallow checking, or s.th? Nah, the docs explicitly says that it will overrride whatever.

REEEEE•4w ago

{equals: false} is to explicitly make it so no matter what you set the value to (it could literally be the same value again), it will trigger anything that's listening to the signal

FlemmingOP•4w ago

Okay, see your point There is another memo in the resource source *on

REEEEE•4w ago

Memos have the same equals handling but you have to also set that yourself but createResource doesn't expose a way to set that right now In the eyes of the memo for resource, your previous object and your next object are equal so it doesn't rerun Because they're the same obj

FlemmingOP•4w ago

Yup, I understand! Thank you very much for taking the time!

REEEEE•4w ago

No problem!

Gaming

Programming

createSignal equals: false on mutable object value

Did you find this page helpful?