Define selection constants (select all 1) by sfc-gh-dmatthews · Pull Request #13794 · streamlit/streamlit

sfc-gh-dmatthews · 2026-02-03T09:14:36Z

Describe your changes

This introduces two constants that will be used to create a select-all feature for st.multiselect. This is not functionally connected and not available to the frontend. This will be implemented in the next PR in the stack.

Screenshot or video (only for visual changes)

GitHub Issue Link (if applicable)

Testing Plan

Explanation of why no additional tests are needed
Unit Tests (JS and/or Python)
E2E Tests
Any manual testing needed?

Contribution License Agreement

By submitting this pull request you agree that all contributions to this project are made under the Apache 2.0 license.

snyk-io · 2026-02-03T09:14:47Z

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github-actions · 2026-02-03T09:14:53Z

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sfc-gh-dmatthews · 2026-02-03T09:14:57Z

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github-actions · 2026-02-03T09:24:51Z

📉 Frontend coverage change detected

The frontend unit test (vitest) coverage has decreased by 0.0600%

Current PR: 86.9500% (14013 lines, 1828 missed)
Latest develop: 87.0100% (13997 lines, 1817 missed)

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github-actions · 2026-02-03T09:54:45Z

Summary

This PR introduces two constants (SELECT_ALL_ID and SELECT_MATCHES_ID) and handler logic for a future "select all" feature in the Multiselect widget. The changes are part of a stacked PR series where this is the foundational plumbing work. The constants define special option IDs that will be used to identify "Select All" and "Select X Matches" dropdown options.

Files changed:

frontend/lib/src/components/shared/Dropdown/VirtualDropdown.tsx - Added constant definitions
frontend/lib/src/components/shared/Dropdown/index.ts - Exported the new constants
frontend/lib/src/components/widgets/Multiselect/Multiselect.tsx - Added handler logic and a ref for filtered matches

Code Quality

The code follows TypeScript and React best practices:

Constants naming: Well-named with double underscore prefix (__SELECT_ALL__, __SELECT_MATCHES__) to clearly indicate internal/special IDs that won't conflict with user data.
Proper exports: Constants are correctly exported through the index barrel file for clean imports.
Handler logic (Multiselect.tsx:148-174): The generateNewState function properly handles the new special IDs with:
- Correct filtering of unselected values
- Proper respect for maxSelections limit
- Clean, readable code with helpful comments
Dependency array update (Multiselect.tsx:184): The useCallback dependency array is correctly updated to include element.maxSelections and element.options.
Ref naming: The new ref follows the naming convention with Ref suffix (selectMatchesRef).

Minor observation: The selectMatchesRef is initialized but never populated in this PR. This is intentional per the PR description ("This will be implemented in the next PR in the stack"), so currently if SELECT_MATCHES_ID were triggered, it would add an empty array. This is acceptable given the stacked PR approach.

Test Coverage

The PR adds functional handler logic in generateNewState but no unit tests are included. While the PR description states "This is not functionally connected and not available to the frontend," the handler logic is present and could be tested independently.

Recommendation: Consider adding unit tests for the new handler logic in Multiselect.test.tsx:

Test that SELECT_ALL_ID adds all unselected options
Test that SELECT_ALL_ID respects maxSelections limit
Test that SELECT_MATCHES_ID uses values from the ref
Test that SELECT_MATCHES_ID respects maxSelections limit

Example test structure:

describe("generateNewState with special selection IDs", () => {
  it("selects all unselected options when SELECT_ALL_ID is selected", async () => {
    // Setup and verify all options are selected
  })

  it("respects maxSelections when SELECT_ALL_ID is selected", async () => {
    // Verify only remaining slots are filled
  })
})

However, given this is explicitly part 1 of a multi-PR feature stack and the UI to trigger these IDs isn't exposed yet, deferring tests to subsequent PRs is a reasonable approach.

Backwards Compatibility

No breaking changes. The changes are purely additive:

New constants added (no impact on existing code)
New ref added (no impact on existing behavior)
Handler logic only triggers for specific new IDs that don't exist in current dropdown options
Existing generateNewState behavior for "remove", "clear", and regular "select" is unchanged

Security & Risk

No security concerns identified:

Constants are client-side only and used for UI logic
The double underscore prefix ensures these won't conflict with user-provided option values
No user input is directly used in security-sensitive operations

Low regression risk:

Changes are isolated to the Multiselect component
Existing functionality is not modified
The special IDs are not yet exposed through the UI

Recommendations

Consider adding unit tests for the new generateNewState handler logic, even if the full feature isn't connected yet. This ensures the foundational logic is correct before building on top of it. (Optional for this PR, could be addressed in subsequent PRs)
Minor code suggestion: The remainingSlots calculation appears twice with identical logic. Consider extracting to a helper:

const getRemainingSlots = (): number => 
  element.maxSelections > 0 ? element.maxSelections - value.length : Infinity

// Then use: unselectedValues.slice(0, getRemainingSlots())

This is a minor suggestion and not required for approval.

Verdict

APPROVED: The code is well-structured, follows best practices, and correctly implements the foundational plumbing for a select-all feature. The lack of tests is noted but acceptable given this is part of a stacked PR workflow where the feature isn't yet exposed to users. The changes are backwards compatible with no security or regression risks.

This is an automated AI review using opus-4.5-thinking. Please verify the feedback and use your judgment.

Copilot

Pull request overview

This PR introduces foundational constants and logic for a select-all feature in the multiselect widget. It defines two special option IDs (SELECT_ALL_ID and SELECT_MATCHES_ID) and implements the selection logic for these options within the generateNewState callback, including proper handling of maxSelections limits.

Changes:

Defines two constants (SELECT_ALL_ID, SELECT_MATCHES_ID) for special dropdown options
Implements selection logic for "select all" and "select matches" functionality with maxSelections support
Adds a ref (selectMatchesRef) to store filtered matches for future use
Updates dependency array to include element.maxSelections and element.options

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
`frontend/lib/src/components/shared/Dropdown/VirtualDropdown.tsx`	Defines two special constants for select-all option IDs
`frontend/lib/src/components/shared/Dropdown/index.ts`	Exports the new constants alongside VirtualDropdown
`frontend/lib/src/components/widgets/Multiselect/Multiselect.tsx`	Imports constants, adds ref for filtered matches, implements select-all logic in generateNewState with maxSelections handling

Copilot · 2026-02-03T18:42:38Z

frontend/lib/src/components/widgets/Multiselect/Multiselect.tsx

+
+            // Respect maxSelections limit
+            if (element.maxSelections > 0) {
+              const remainingSlots = element.maxSelections - value.length
+              return [...value, ...filteredValues.slice(0, remainingSlots)]
+            }
+
+            return [...value, ...filteredValues]


The logic for SELECT_MATCHES_ID doesn't filter out already-selected values, which could result in duplicate values in the returned array. The filteredValues from the ref should be filtered to exclude values already in the current selection.

Compare with the SELECT_ALL_ID case on lines 150-152, which correctly filters to get only unselected values. The SELECT_MATCHES_ID case should follow the same pattern:

const unselectedMatches = filteredValues.filter(opt => !value.includes(opt))

Then use unselectedMatches instead of filteredValues when building the return value.

Suggested change

// Respect maxSelections limit

if (element.maxSelections > 0) {

const remainingSlots = element.maxSelections - value.length

return [...value, ...filteredValues.slice(0, remainingSlots)]

}

return [...value, ...filteredValues]

const unselectedMatches = filteredValues.filter(

opt => !value.includes(opt)

)

// Respect maxSelections limit

if (element.maxSelections > 0) {

const remainingSlots = element.maxSelections - value.length

return [...value, ...unselectedMatches.slice(0, remainingSlots)]

}

return [...value, ...unselectedMatches]

This seems like a legitimate bug. Have you had a chance to investigate this @sfc-gh-dmatthews ?

I think this is just an imperfect separation of the backend and frontend logic. In the next PR, the filtered options are initialized from an already filtered list that excludes selected items.

frontend/lib/src/components/widgets/Multiselect/Multiselect.tsx

Copilot · 2026-02-03T18:42:39Z

frontend/lib/src/components/widgets/Multiselect/Multiselect.tsx

+              const remainingSlots = element.maxSelections - value.length
+              return [...value, ...unselectedValues.slice(0, remainingSlots)]


When maxSelections is set and value.length equals maxSelections, remainingSlots will be 0. However, if there's a bug where value.length somehow exceeds maxSelections, remainingSlots becomes negative, and slice(0, negativeNumber) would still return values (slice with negative end index counts from the end of the array).

Consider adding a Math.max guard to ensure remainingSlots is never negative:

const remainingSlots = Math.max(0, element.maxSelections - value.length)

This same issue exists on lines 156 and 169.

sfc-gh-dmatthews · 2026-02-16T21:33:44Z

Merge activity

Feb 16, 9:33 PM UTC: A user started a stack merge that includes this pull request via Graphite.
Feb 16, 9:34 PM UTC: Graphite couldn't merge this PR because it had merge conflicts.
Feb 16, 11:04 PM UTC: A user started a stack merge that includes this pull request via Graphite.
Feb 16, 11:05 PM UTC: @sfc-gh-dmatthews merged this pull request with Graphite.

## Describe your changes This introduces two constants that will be used to create a select-all feature for `st.multiselect`. This is not functionally connected and not available to the frontend. This will be implemented in the next PR in the stack. ## Screenshot or video (only for visual changes) ## GitHub Issue Link (if applicable) ## Testing Plan - Explanation of why no additional tests are needed - Unit Tests (JS and/or Python) - E2E Tests - Any manual testing needed? --- **Contribution License Agreement** By submitting this pull request you agree that all contributions to this project are made under the Apache 2.0 license.

sfc-gh-dmatthews changed the title ~~Define selection constants~~ Define selection constants for select-all feature Feb 3, 2026

sfc-gh-dmatthews changed the title ~~Define selection constants for select-all feature~~ Define selection constants (select all 1) Feb 3, 2026

sfc-gh-dmatthews added security-assessment-completed impact:internal PR changes only affect internal code change:feature PR contains new feature or enhancement implementation ai-review If applied to PR or issue will run AI review workflow labels Feb 3, 2026

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sfc-gh-bnisco approved these changes Feb 3, 2026

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sfc-gh-bnisco force-pushed the 02-02-multiselect-selection-plumbing branch from 8096ee9 to 7132679 Compare February 3, 2026 17:11

sfc-gh-dmatthews force-pushed the 02-02-multiselect-selection-plumbing branch from 7132679 to 44abccb Compare February 3, 2026 18:38

sfc-gh-dmatthews marked this pull request as ready for review February 3, 2026 18:39

Copilot AI review requested due to automatic review settings February 3, 2026 18:39

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sfc-gh-dmatthews force-pushed the 02-02-multiselect-selection-plumbing branch 2 times, most recently from 93808e8 to 0adf09d Compare February 3, 2026 23:55

sfc-gh-dmatthews force-pushed the 02-02-multiselect-selection-plumbing branch 10 times, most recently from 7336765 to f184585 Compare February 6, 2026 02:15

sfc-gh-dmatthews mentioned this pull request Feb 6, 2026

Select all or select all matches in st.multiselect (plus drop down styling) #13015

Closed

sfc-gh-dmatthews force-pushed the 02-02-multiselect-selection-plumbing branch 5 times, most recently from de31a73 to 904afcb Compare February 13, 2026 06:35

sfc-gh-dmatthews force-pushed the 02-02-multiselect-selection-plumbing branch from 904afcb to ab76d8e Compare February 15, 2026 04:33

Define selection constants

9465966

sfc-gh-dmatthews force-pushed the 02-02-multiselect-selection-plumbing branch from ab76d8e to 9465966 Compare February 16, 2026 21:53

sfc-gh-dmatthews merged commit 351cfb6 into develop Feb 16, 2026
43 checks passed

sfc-gh-dmatthews deleted the 02-02-multiselect-selection-plumbing branch February 16, 2026 23:05

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		const remainingSlots = element.maxSelections - value.length
		return [...value, ...unselectedValues.slice(0, remainingSlots)]

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Summary

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