fix(signals): keep computed values in sync in withPreviousValueOnLoading and withValueOnLoading - #5225
Open
gregorycode wants to merge 3 commits into
Open
fix(signals): keep computed values in sync in withPreviousValueOnLoading and withValueOnLoading#5225gregorycode wants to merge 3 commits into
gregorycode wants to merge 3 commits into
Conversation
Read `isLoading` in a tracked context in the `value` proxy of `withPreviousValueOnLoading`. Previously, `isLoading` was read with `untracked`, so a computed that first read `value()` while loading recorded no dependencies and stayed stuck on the cached value after the request resolved. Closes ngrx#5224 Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
✅ Deploy Preview for ngrx-io ready!Built without sensitive environment variables
To edit notification comments on pull requests, go to your Netlify project configuration. |
rainerhahnekamp
requested changes
Sep 22, 2026
rainerhahnekamp
left a comment
rainerhahnekamp
left a comment
Contributor
There was a problem hiding this comment.
I suggested an alternative approach where we only track the value and not also the isLoading signal. Let me know what you think.
| await resolveWithValue([1, 2, 3]); | ||
| expect(value()).toEqual([1, 2, 3]); | ||
| }); | ||
|
|
Contributor
There was a problem hiding this comment.
Could we also cover a loading-only change? A consumer of value() should not recompute when reload() starts and the value stays the same, but it should recompute when a new value arrives. This test passes locally with the implementation suggested below.
Suggested change
| it('does not recompute consumers when only the loading state changes', async () => { | |
| const { resource, initLoading, reload, resolveWithValue } = | |
| createTestResource<number[]>(); | |
| withPreviousValueOnLoading().apply(resource); | |
| initLoading(); | |
| await resolveWithValue([1, 2, 3]); | |
| const readValue = vi.fn(() => resource.value()); | |
| const value = computed(readValue); | |
| expect(value()).toEqual([1, 2, 3]); | |
| expect(readValue).toHaveBeenCalledTimes(1); | |
| reload(); | |
| expect(resource.isLoading()).toBe(true); | |
| expect(value()).toEqual([1, 2, 3]); | |
| expect(readValue).toHaveBeenCalledTimes(1); | |
| await resolveWithValue([4, 5]); | |
| expect(value()).toEqual([4, 5]); | |
| expect(readValue).toHaveBeenCalledTimes(2); | |
| }); | |
Comment on lines
41
to
42
| if (!resource.isLoading()) { | ||
| value = Reflect.apply(target, thisArg, args); |
Contributor
There was a problem hiding this comment.
Could we always read the value signal and keep isLoading untracked? Please also retain the untracked import.
Suggested change
| if (!resource.isLoading()) { | |
| value = Reflect.apply(target, thisArg, args); | |
| const currentValue = Reflect.apply(target, thisArg, args); | |
| if (!untracked(resource.isLoading)) { | |
| value = currentValue; |
Always read the underlying `value` signal in the `value` proxy and keep `isLoading` untracked. Consumers of `value()` no longer recompute when only the loading state changes, but still recompute when a new value arrives.
rainerhahnekamp
approved these changes
Sep 22, 2026
rainerhahnekamp
left a comment
rainerhahnekamp
left a comment
Contributor
There was a problem hiding this comment.
seems ok to me. thanks
gregorycode
changed the title
gregorycode
changed the title
This branch has not been deployed
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
The issue: when a resource is extended with
withPreviousValueOnLoading(), a computed that first readsresource.value()while the resource is loading staysundefinedafter the request resolves.With this fix, the
valueproxy always reads the underlyingvaluesignal while keepingisLoadinguntracked, so consumers stay in sync and the previousvalueis still returned while loading.PR Checklist
Please check if your PR fulfills the following requirements:
PR Type
What kind of change does this PR introduce?
What is the current behavior?
Closes #5224
What is the new behavior?
Does this PR introduce a breaking change?
Other information