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Solid v2.0.0-beta.10 batched parent & derived signals manual update is neglected for derived signals #2692
Description
Describe the bug
When updating parent signal and derived signal in one "batch", the derived signal update has no effect independent of update order.
const [original, setOriginal] = createSignal(0);
const [derived, setDerived] = createSignal(original);
function onClick() {
setOriginal(1); // sets both derived signals to 1
setDerived(2); // doesn't do anything
}This happens only for first call of onClick, because on second call original signal already has new value and so doesn't update - this allows derived signal to update.
This can be mitigated right now with flush
function onClick() {
setOriginal(1); // sets both derived signals to 1
flush();
setDerived(2); // sets derived signal to 2
}but flush can't be used in e.g. onSettled
and flushing it at that point makes more updates
Your Example Website or App
Steps to Reproduce the Bug or Issue
- Go to link
- Click the button
- See that both signals have value of 1 instead of 1 and 2
- Click the button again
- See that signals have now values of 1 and 2
Expected behavior
Updates to signals should be applied in call order.
Screenshots or Videos
No response
Platform
- OS: Windows 10
- Browser: Chrome
- Version: Solid v2.0.0-beta.10
Additional context
No response
Activity
[-]Solid v2.0.0-beta.10 batched signals manual update is neglected for derived signals[/-][+]Solid v2.0.0-beta.10 batched parent & derived signals manual update is neglected for derived signals[/+]ryansolid commentedon May 4, 2026
There is still an open question about order. Making order matter would be pretty difficult because things don't evaluate immediately (without flush). So we have to take a side I believe write should override recompute, but order isn't going to matter here I think. Simply write trumps derivation on the same tick.
Derived Stores are trickier. The only way to be consistent is have them similarly cancel. It isn't really possible to enforce ordering and to know the state you are in coming in to either.
fix(signals): preserve manual writes to derived state (#2692)
ryansolid commentedon May 11, 2026
I just went with write beats derived in the same tick. Fixed in beta.11.
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