Add filter() method to PCollection in TypeScript SDK by junaiddshaukat · Pull Request #37408 · apache/beam

junaiddshaukat · 2026-01-24T06:11:47Z

Description:

Adds a filter() method to the PCollection class in the TypeScript SDK, addressing a TODO from README-dev.md.

Fixes #37407

Changes

Added filter() method to PCollection class in pvalue.ts
Added 5 test cases for the filter functionality in primitives_test.ts

Usage Examples

// Basic filtering
const evens = pcoll.filter(x => x % 2 === 0);

// Filter with context
const filtered = pcoll.filter((x, threshold) => x > threshold, 5);

// Filter strings
const aWords = words.filter(s => s.startsWith('a'));

Implementation Details

Follows the same pattern as existing map() and flatMap() methods
Uses parDo internally with a process function that returns [element] or []
Supports optional context parameter for side inputs, counters, etc.
Added proper TypeScript constraint (ContextT extends Object | undefined) to match parDo signature

Tests Added

Test Case	Description
`runs a filter`	Basic even number filtering
`runs a filter with predicate returning false for all`	Empty result case
`runs a filter with predicate returning true for all`	All elements pass
`runs a filter with context`	Context parameter support
`runs a filter on strings`	Non-numeric type support

Checklist

Tests added and passing (297 tests total)
Follows existing code patterns (map, flatMap)
Documentation added (JSDoc comments with examples)
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- Add filter() method following same pattern as map() and flatMap() - Add 5 test cases covering various filtering scenarios - Support optional context parameter for side inputs

gemini-code-assist · 2026-01-24T06:12:02Z

Summary of Changes

Hello @junaiddshaukat, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the TypeScript SDK by introducing a filter() method to the PCollection class. This addition provides a familiar and powerful way to selectively process data within a pipeline, allowing users to easily retain only the elements that meet specific criteria. The implementation is robust, leveraging existing primitives and supporting flexible predicate functions, including those that require additional context.

Highlights

New filter() method for PCollection: A filter() method has been added to the PCollection class in the TypeScript SDK, allowing users to filter elements based on a provided predicate function. This addresses a TODO item from README-dev.md and mirrors the functionality of JavaScript's Array.filter().
Internal Implementation using parDo: The filter() method is implemented internally using the existing parDo primitive. It leverages a process function that returns the element wrapped in an array if the predicate is true, or an empty array if false, effectively filtering the PCollection.
Context Parameter Support: The new filter() method supports an optional context parameter, allowing the predicate function to access side inputs, counters, or other contextual data, aligning with the parDo signature.
Comprehensive Test Coverage: Five new test cases have been added to primitives_test.ts to validate the filter() functionality. These tests cover basic filtering, cases where all or no elements pass, filtering with context, and filtering on string types.
Documentation and Code Patterns: The filter() method includes JSDoc comments with usage examples. Its implementation follows the established patterns of existing map() and flatMap() methods within the SDK.

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junaiddshaukat · 2026-01-24T06:17:20Z

Hi @damccorm

This PR adds a filter() method to PCollection, addressing the TODO in README-dev.md. It follows the same pattern as map() and flatMap() with 5 test cases covering various scenarios.

Fixes #37407

Would appreciate your review when you have time. Thanks!

github-actions · 2026-01-24T06:45:48Z

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damccorm · 2026-01-26T18:24:24Z

/gemini review

gemini-code-assist

Code Review

This pull request introduces a filter() method to the PCollection class in the TypeScript SDK, which is a great and much-needed addition. The implementation correctly follows the pattern of existing methods like map() and flatMap(), and it's backed by a comprehensive set of test cases that cover various scenarios including edge cases and context usage.

I have one suggestion to refine the implementation by using a generator function. This would align it more closely with the map() method's implementation and could offer a minor performance benefit by avoiding unnecessary array allocations.

Overall, this is a solid contribution. Well done!

sdks/typescript/src/apache_beam/pvalue.ts

damccorm

Thanks, LGTM

- Add filter() method following same pattern as map() and flatMap() - Add 5 test cases covering various filtering scenarios - Support optional context parameter for side inputs

Add filter() method to PCollection in TypeScript SDK

9d2edd6

- Add filter() method following same pattern as map() and flatMap() - Add 5 test cases covering various filtering scenarios - Support optional context parameter for side inputs

github-actions bot added the typescript label Jan 24, 2026

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gemini-code-assist bot reviewed Jan 26, 2026

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damccorm approved these changes Jan 26, 2026

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damccorm merged commit 911ec6a into apache:master Jan 26, 2026
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Add filter() method to PCollection in TypeScript SDK#37408

Add filter() method to PCollection in TypeScript SDK#37408
damccorm merged 1 commit intoapache:masterfrom
junaiddshaukat:add-filter-method-typescript-sdk

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junaiddshaukat commented Jan 24, 2026

Description:

Changes

Usage Examples

Implementation Details

Tests Added

Checklist

GitHub Actions Tests Status (on master branch)

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