fix(useTemplateRef): handle useTemplateRef edge case with vFor

[edison1105]

close #12731

the underlying problem is

const elements1 = useTemplateRef('testref') 
// instance.refs['testref'] is a shallowRef
instance.refs['testref'].value = [1]  // value is an array

const elements2 = ref() 
// instance.refs['elements2'] is a ref
instance.refs['elements2'].value = [1]  // value is a reactive array

Summary by CodeRabbit

• Bug Fixes

  • Improved handling of template refs in lists to ensure refs collected with v-for are now reactive arrays, providing more accurate and responsive behavior in dynamic list scenarios.

• Tests

  • Added a new test case to verify that refs collected with v-for are properly managed as reactive arrays.

[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	100 kB (+4 B)	38 kB (+7 B)	34.2 kB (-7 B)
vue.global.prod.js	158 kB (+4 B)	57.8 kB (+3 B)	51.4 kB (-5 B)

Usages

Name	Size	Gzip	Brotli
createApp (CAPI only)	46.4 kB (+32 B)	18.2 kB (+5 B)	16.6 kB (-16 B)
createApp	54.4 kB (+32 B)	21.2 kB (+12 B)	19.3 kB (+13 B)
createSSRApp	58.6 kB (+32 B)	22.9 kB (+4 B)	20.9 kB (+9 B)
defineCustomElement	59.2 kB (+32 B)	22.8 kB (+8 B)	20.7 kB (+8 B)
overall	68.4 kB (+32 B)	26.3 kB (+9 B)	24 kB (-25 B)

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commit: 2336e2a

[skirtles-code]

I'm not sure whether it would be considered a problem, but this change would also impact $refs.

[edison1105]

I'm not sure whether it would be considered a problem, but this change would also impact $refs.

Thanks for your review. Perhaps this cannot be regarded as a problem, because this kind of behavior already exists in PROD.

• open Playground - main branch
• click the button twice, see console.log
• i.refs['elements2'] is a Proxy array in PROD

[skirtles-code]

I would be nervous about drawing any conclusions based on that example. getCurrentInstance() is undocumented, so to hit that edge case using documented APIs you'd need to mix <script setup> and the Options API. Not only is it inconsistent between DEV and PROD, it also behaves differently depending on whether you use ref() or ref([]):

• Playground

It strikes me as an unintentional edge case, rather than something we should be using as precedent.

---

I'm not entirely clear why $refs isn't reactive, but personally I think it's a decision that should be revisited. That might also allow the implementation of useTemplateRef to be simplified too.

But, given $refs currently isn't reactive, I'd be hesitant to introduce partial reactivity in just the v-for case unless we're planning to move towards full reactivity in future.

[coderabbitai]

Walkthrough

A new test verifies that template refs collected via v-for are reactive arrays. The implementation is updated so that string refs assigned to arrays are now wrapped with shallowReactive, ensuring reactivity. No changes were made to exported APIs or public interfaces.

Changes

Files	Change Summary
packages/runtime-core/tests/helpers/useTemplateRef.spec.ts	Added test to verify that refs collected in v-for are reactive arrays.
packages/runtime-core/src/rendererTemplateRef.ts	Updated setRef to wrap array refs with shallowReactive for string refs in template refs.

Sequence Diagram(s)

sequenceDiagram
    participant Component
    participant Renderer
    participant Reactivity

    Component->>Renderer: Render elements with v-for and template ref
    Renderer->>Renderer: Collect refs for each element
    Renderer->>Reactivity: Wrap refs array with shallowReactive
    Reactivity-->>Renderer: Return reactive array
    Renderer->>Component: Assign reactive array to template ref

Loading

Assessment against linked issues

Objective	Addressed	Explanation
Ensure useTemplateRef returns Ref, not ShallowRef, and maintains reactivity (#12731)	✅
Ensure collected refs in v-for are reactive arrays matching documentation (#12731)	✅

Possibly related issues

• useTemplateRef Fails to Populate Ref Array When Slot Content Is Rendered in v-for #12489: The changes make refs collected in a v-for reactive arrays using shallowReactive, directly addressing the issue described.

Poem

A bunny hopped through code so neat,
Making refs in loops reactive and sweet.
With shallowReactive arrays,
Now refs update in all ways—
A hop, a test, and bugs in retreat!
🐇✨

✨ Finishing Touches

• 📝 Generate Docstrings

---

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[coderabbitai]

Actionable comments posted: 0

🔭 Outside diff range comments (1)

packages/runtime-core/src/rendererTemplateRef.ts (1)

126-134: Inconsistent behaviour between string refs and object refs

shallowReactive([refValue]) is created only when _isString is true.
For the _isRef branch a plain array is still assigned (ref.value = [refValue]), meaning that:

<li :ref="myShallowRef" ref_for />

will not receive a reactive array, whereas

<li ref="myKey" ref_for />

will.

Unless there is a deliberate reason to preserve this asymmetry, consider applying the same shallowReactive wrapping to the _isRef path for consistency and to avoid surprising API differences.

-            ref.value = [refValue]
+            ref.value = shallowReactive([refValue])

🧹 Nitpick comments (2)

packages/runtime-core/src/rendererTemplateRef.ts (1)

14-14: Minor: keep import list alphabetised for easier diff-scanning

shallowReactive was inserted between isRef and toRaw, breaking the previous alphabetical order of the imported symbols. A consistent ordering reduces merge-conflicts and makes future diffs easier to read.

packages/runtime-core/__tests__/helpers/useTemplateRef.spec.ts (1)

76-126: Nice coverage – consider asserting isReactive(t1.value) as well

The new test correctly checks that instance.refs['refKey'] is reactive, but it never verifies that t1.value – the value returned by useTemplateRef – is the same reactive proxy. A quick extra assertion would guarantee the public API receives the reactive array you expect:

expect(t1!.value).toBe(currentInstance.refs['refKey'])
expect(isReactive(t1!.value)).toBe(true)

Adding this would catch a future regression where refs stays reactive but useTemplateRef returns a plain array.

📜 Review details

Configuration used: CodeRabbit UI
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📥 Commits

Reviewing files that changed from the base of the PR and between 82da43d and 2336e2a.

📒 Files selected for processing (2)

• packages/runtime-core/__tests__/helpers/useTemplateRef.spec.ts (2 hunks)
• packages/runtime-core/src/rendererTemplateRef.ts (2 hunks)

🧰 Additional context used

🧬 Code Graph Analysis (1)

packages/runtime-core/__tests__/helpers/useTemplateRef.spec.ts (3)

packages/runtime-core/src/component.ts (1)

• currentInstance (708-708)

packages/runtime-core/src/helpers/useTemplateRef.ts (1)

• useTemplateRef (8-40)

packages/runtime-test/src/serialize.ts (1)

• serializeInner (22-33)