fix(websub): handle empty channels map in mapWebSubAPIModelToAPI

[SAY-5]

Purpose

Resolves #1995.

mapWebSubChannelsModelToAPI returned a nil *map for empty or nil input, and the caller in mapWebSubAPIModelToAPI then dereferenced that nil pointer when assigning to api.WebSubAPI.Channels (a value-type map). Any Get, List, or Update return path panicked for a WebSub API stored with an empty channels map. The bug was originally noted in #1992 (review comment).

Goals

Make the conversion safe for empty/nil channel inputs and have it always produce a usable (non-nil) map suitable for direct assignment to the value-type Channels field.

Approach

mapWebSubChannelsModelToAPI now returns map[string]api.WebSubChannel directly instead of *map[string]api.WebSubChannel. For empty/nil input it returns an empty (non-nil) map. The call site in mapWebSubAPIModelToAPI drops the * indirection.

User stories

N/A (defect fix).

Documentation

N/A — internal helper behavior, no user-facing API change.

Automation tests

• Unit tests
  • TestWebSubAPI_MapModelToAPI_EmptyChannelsDoesNotPanic exercises mapWebSubAPIModelToAPI with a nil channel map and an empty channel map, asserting it does not panic and that the resulting Channels map is non-nil and empty. On main both subtests fail with "runtime error: invalid memory address or nil pointer dereference"; with this fix they pass.
  • TestWebSubAPI_MapChannelsModelToAPI_NeverReturnsNil pins the helper contract that nil and empty inputs both yield a non-nil map.
• Existing TestWebSubAPI_* tests in platform-api/src/internal/service/websub_api_test.go continue to pass.

$ go test ./internal/service/ -count=1 -timeout 180s
ok  	platform-api/src/internal/service	0.418s

Security checks

• Followed secure coding standards in http://wso2.com/technical-reports/wso2-secure-engineering-guidelines? yes
• Ran FindSecurityBugs plugin and verified report? N/A (no security-relevant change)
• Confirmed that this PR doesn't commit any keys, passwords, tokens, usernames, or other secrets? yes

Samples

N/A.

Related PRs

• Add platform API changes for WebBroker APIs #1992 — change that introduced the call site; this PR addresses the review comment referenced in Fix nil-pointer dereference when mapping WebSub API channels in mapWebSubAPIModelToAPI #1995.

Test environment

• Go 1.26.2 (matches platform-api-pr-check.yml), macOS arm64 locally.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 41929be2-88d3-43d5-aa54-aa4f152f98ce

📥 Commits

Reviewing files that changed from the base of the PR and between f7a2827 and d2d5911.

📒 Files selected for processing (2)

• platform-api/src/internal/service/websub_api.go
• platform-api/src/internal/service/websub_api_test.go

---

📝 Walkthrough

Summary

This PR fixes a runtime panic that occurred during Get, List, and Update operations on WebSub APIs that were stored with empty or nil channel maps.

Root Cause

The mapping helper mapWebSubChannelsModelToAPI previously returned a pointer to a map (*map[string]api.WebSubChannel) and would return nil when the input map was empty or nil. The caller would then dereference this potentially nil pointer when assigning to the value-typed api.WebSubAPI.Channels field, causing a panic.

Changes Made

platform-api/src/internal/service/websub_api.go:

• Changed mapWebSubChannelsModelToAPI return type from *map[string]api.WebSubChannel to map[string]api.WebSubChannel
• Removed the early nil check that returned nil for empty maps; the function now always returns a (possibly empty) non-nil map
• Updated the call site in mapWebSubAPIModelToAPI to remove the pointer dereference: *mapWebSubChannelsModelToAPI(...) → mapWebSubChannelsModelToAPI(...)
• Added documentation comments explaining that the helper always returns a non-nil map to safely support value-type map fields

platform-api/src/internal/service/websub_api_test.go:

• Added TestWebSubAPI_MapModelToAPI_EmptyChannelsDoesNotPanic to verify that mapping with nil or empty channel maps does not cause a panic and produces a non-nil, empty Channels map
• Added TestWebSubAPI_MapChannelsModelToAPI_NeverReturnsNil to pin the helper contract and ensure it always returns a non-nil map

Impact

• Fixes panics in Get, List, and Update operations for WebSub APIs with empty channel maps (fixes issue #1995)
• All changes are to unexported helper functions; no public API modifications
• Existing tests continue to pass

Walkthrough

This pull request fixes a nil-pointer dereference in the WebSub API channel mapping layer. The mapWebSubChannelsModelToAPI function was refactored to return a non-nil map[string]api.WebSubChannel instead of a nullable pointer. The corresponding caller mapWebSubAPIModelToAPI was updated to use the direct return value. Two new unit tests validate the fix: one ensures the top-level mapper handles empty channels without panicking, and the other verifies the channel mapper always returns a non-nil map.

Suggested reviewers

• VirajSalaka
• renuka-fernando
• malinthaprasan
• AnuGayan
• senthuran16
• tharindu1st
• RakhithaRR

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main fix: handling an empty channels map in mapWebSubAPIModelToAPI to prevent nil-pointer dereference.
Description check	✅ Passed	The description is comprehensive and follows the template structure, covering purpose, goals, approach, documentation, automation tests, security checks, and test environment details.
Linked Issues check	✅ Passed	The PR addresses issue #1995 by changing mapWebSubChannelsModelToAPI to return a non-nil map and updating the call site in mapWebSubAPIModelToAPI, eliminating the nil-pointer dereference when mapping empty channels.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to fixing the nil-pointer dereference issue: the helper function signature change, the map return logic, the call site update, and supporting unit tests.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 golangci-lint (2.12.2)

level=error msg="[linters_context] typechecking error: pattern ./...: directory prefix . does not contain modules listed in go.work or their selected dependencies"

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}