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Use AllowMultiple as signal for array query parameters#620

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rithwik-01 wants to merge 3 commits into
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rithwik-01:fix-array-query-param-type
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Use AllowMultiple as signal for array query parameters#620
rithwik-01 wants to merge 3 commits into
kubernetes:masterfrom
rithwik-01:fix-array-query-param-type

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@rithwik-01 rithwik-01 commented Jun 27, 2026 •
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Use AllowMultiple() as the signal for emitting type: array in OpenAPI schemas instead of detecting a [] prefix on DataType. When AllowMultiple() is true, the [] prefix is only stripped to derive the element type.

Changes:

  • pkg/builder/openapi.go (v2): array detection via AllowMultiple(), CollectionFormat: "multi" always set for array params
  • pkg/builder3/openapi.go (v3): same, with Style: "form" + Explode: true for array params
  • []byte stays scalar naturally through OpenAPITypeFormat: no special guard needed
  • []string without AllowMultiple intentionally errors as a misconfiguration
  • Tests: table-driven, uses restfuladapter.ParamAdapter (same adapter as runtime)

Relationship to kubernetes/kubernetes#140050

This PR is a necessary precondition for fixing that issue, but does not close it alone. The Kubernetes apiserver's typeToJSON function (staging/src/k8s.io/apiserver/pkg/endpoints/installer.go) explicitly strips []string → "string" and []int32 → "integer" with a TODO referencing the go-restful limitation this PR addresses. A companion PR to remove those cases from typeToJSON is needed to fully resolve the issue.

Refs: kubernetes/kubernetes#140050

@rithwik-01
Detect array query parameter types in OpenAPI builders
b39be9e 
When a restful parameter DataType is prefixed with '[]' (e.g. '[]string',
'[]integer'), emit type: array with the correct items sub-schema instead
of treating it as a scalar type.

This allows upstream callers to pass compound DataType values through
restful plumbing without losing the array semantics, fixing OpenAPI spec
generation for parameters like PodExecOptions.Command []string.

Related: kubernetes/kubernetes#140050
@kubernetes-prow kubernetes-prow Bot requested review from jpbetz and sttts June 27, 2026 05:02
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[APPROVALNOTIFIER] This PR is NOT APPROVED

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@kubernetes-prow kubernetes-prow Bot added the cncf-cla: yes Indicates the PR's author has signed the CNCF CLA. label Jun 27, 2026
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Welcome @rithwik-01!

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@kubernetes-prow kubernetes-prow Bot added the size/M Denotes a PR that changes 30-99 lines, ignoring generated files. label Jun 27, 2026
@rithwik-01

rithwik-01 commented Jun 27, 2026

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@jpbetz / @sttts Can you please review this PR? Happy to provide more context or make changes if needed.

@rithwik-01
fix: guard []byte scalar in array detection, add collectionFormat/Sty…
382bbc2 
…le/Explode for AllowMultiple

- Check OpenAPITypeFormat(dataType) before stripping [] prefix so known
  scalar types like "[]byte" (base64-encoded string) aren't incorrectly
  emitted as array[uint8].
- V2: set CollectionFormat="multi" when array parameter has AllowMultiple.
- V3: set Style="form", Explode=true when array parameter has AllowMultiple.
Jefftree
Jefftree reviewed Jul 6, 2026
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See if you can align to use AllowMultiple instead.

@rithwik-01
fix: use AllowMultiple as signal for array query parameters
881c0f0 
Replace []-prefix-based array detection with AllowMultiple() as the
canonical signal for emitting type: array in OpenAPI schemas. The []
prefix is only stripped to derive the element type.

V2: Always set CollectionFormat="multi" for AllowMultiple params.
V3: Always set Style="form" and Explode=true for AllowMultiple params.
[]string without AllowMultiple is treated as a misconfiguration.
@kubernetes-prow kubernetes-prow Bot added size/L Denotes a PR that changes 100-499 lines, ignoring generated files. and removed size/M Denotes a PR that changes 30-99 lines, ignoring generated files. labels Jul 7, 2026
@rithwik-01

rithwik-01 commented Jul 7, 2026

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@Jefftree Thank you for the suggestion.
Updated to use AllowMultiple() as the sole signal for array detection:

  • AllowMultiple()=true → emits type: array with items; [] prefix is only stripped to derive the element type, not for detection
  • []byte stays scalar naturally through OpenAPITypeFormat — no special guard needed
  • []string without AllowMultiple intentionally errors as a misconfiguration (returns to pre-PR behavior rather than silently masking it)
  • V2: CollectionFormat: "multi" always set for AllowMultiple params
  • V3: Style: "form" + Explode: true always set for AllowMultiple params

@rithwik-01 rithwik-01 requested a review from Jefftree July 7, 2026 02:54
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rithwik-01 commented Jul 7, 2026

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/assign

@rithwik-01 rithwik-01 changed the title Detect array query parameter types in OpenAPI builders Use AllowMultiple as signal for array query parameters Jul 7, 2026
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