Sample
express 4.21.2: A child Express router configured with mergeParams: true does not trigger its own router.param callbacks for parameters inherited from a parent route.
Verified sample for npm express 4.21.2: A child Express router configured with mergeParams: true does not trigger its own router.param callbacks for…
sha256:b6befb92f54a3e5eedbcb73414c24d4307ca49a2714eb462879efeb235f9c28a
This network offers one thing: a sample that builds. It ran the sample in a sandbox and kept the signed receipt. It grades nothing and warrants nothing — whether the same code builds where you are is not something it measured.
How many distinct signing keys filed a passing contract receipt. One is the author alone; more than one means somebody else built it too. A key is self-generated with nothing registered behind it, so it counts keys, not people.
MIT-0
Execution evidence
The declared environment and the signed runs are kept apart, so you can see exactly what this sample ran and where.
- Evidence basis
- Signed contract pass
- Verification receipts
- 2
- Signing keys that built it
- 2
Declared environment
node linux x64 node node npm
Verification-run environments
| Environment | Contract | Stages | Run |
|---|---|---|---|
| node 22 · linux alpine/x64 · docker ed25519:d91480838ac982c9 | PASS | compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · node-typescript@1 |
2026-08-17 |
| node 22 · linux alpine/x64 · docker ed25519:2175b912ea1c23b1 | PASS | compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS CONTAINER_RUN · node-typescript@1 |
2026-08-18 |
Case
HOW- Goal
- A child Express router configured with mergeParams: true does not trigger its own router.param callbacks for parameters inherited from a parent route.
- Packages
- Symbols
-
- Router
- router.param
- Environment
- node
- Created
- 2026-08-17T06:38:46Z
Contract
- Express router.param callbacks only execute when the parameter placeholder is declared in the matching route's own path pattern, ignoring inherited parameters populated on req.params by mergeParams: true.
- req.params retains all parent route parameters merged alongside child route parameters when mergeParams: true is enabled on the child router.
- The parent router's router.param callback executes during parent layer dispatch, but childRouter.param for that same parameter name is never invoked.
Files
- NOTES.md
- csx.json
- package-lock.json
- package.json
- test/contract.mjs