fix(go): validate string enum exclusions by AndreyVMarkelov · Pull Request #25089 · OpenAPITools/openapi-generator

AndreyVMarkelov · 2026-10-01T20:45:55Z

Description

Fix Go client generation for string properties constrained by enum and not: { enum: [...] }.

Previously, generated models could accept values excluded by not: enum during JSON unmarshaling. This could make oneOf variants overlap when they were intended to be mutually exclusive.

This change adds validation during generated model unmarshaling so:

allowed enum values are enforced;
excluded enum values are rejected;
nullable enums preserve null semantics;
optional properties remain optional;
untyped not: enum does not incorrectly force a string type;
JSON property matching follows Go encoding/json case-insensitive field matching.

Existing UnmarshalJSON paths for required and additionalProperties models are preserved.

Related reports: #25065 (Java), #25069 (Python).

Tests

Added focused Go generator coverage for:

allowed and excluded string enum values
nullable allowed and excluded enums
optional properties
quoted string values
typed and untyped not: enum
case-insensitive JSON property names
validating UnmarshalJSON generation

Generated Go code compiles and passes runtime validation with go test ./....

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Prompt for AI agents (unresolved issues)


Check if these issues are valid — if so, understand the root cause of each and fix them. When an issue isn't valid or won't be fixed in this PR, reply in its thread with the reason and then resolve the thread. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="modules/openapi-generator/src/main/resources/go/model_simple.mustache">

<violation number="1" location="modules/openapi-generator/src/main/resources/go/model_simple.mustache:510">
P2: For a required `Foo` with a default, `{"foo":""}` reaches this branch and leaves both `foo` and the defaulted `Foo` in `allProperties`; unmarshalling the marshaled map can let the alias overwrite the default. Remove or normalize the matched alias before adding the canonical default.</violation>
</file>

wing328 · 2026-10-05T07:49:15Z

thanks for the PR

cc Go technical committee: @antihax (2017/11) @grokify (2018/07) @kemokemo (2018/09) @jirikuncar (2021/01) @ph4r5h4d (2021/04) @lwj5 (2023/04)

wing328 · 2026-10-05T08:10:43Z

@@ -0,0 +1,106 @@
+openapi: 3.1.0


with the change in this PR, i generated a go client using this spec but got the following errors when running go test:

.\model_optional_enum_child.go:63:16: o._ undefined (type *OptionalEnumChild has no field or method _) .\model_optional_enum_child.go:70:4: o._ undefined (type *OptionalEnumChild has no field or method _) .\model_optional_enum_child.go:70:16: decoded._ undefined (type struct{Kind *string "json:\"kind,omitempty\""; _ *string "json:\"-,omitempty\""; Label *string "json:\"label,omitempty\""} has no field or method _) .\model_optional_enum_parent.go:77:25: o._ undefined (type *OptionalEnumParent has no field or method _) .\model_optional_enum_parent.go:81:12: o._ undefined (type *OptionalEnumParent has no field or method _) .\model_optional_enum_parent.go:87:25: o._ undefined (type *OptionalEnumParent has no field or method _) .\model_optional_enum_parent.go:90:11: o._ undefined (type *OptionalEnumParent has no field or method _) .\model_optional_enum_parent.go:120:14: o._ undefined (type OptionalEnumParent has no field or method _) .\model_optional_enum_parent.go:121:24: o._ undefined (type OptionalEnumParent has no field or method _) .\model_optional_enum_parent.go:90:11: too many errors

did you encounter similar errors when testing the change locally?

fixing. Agree

Fixed. The - property was only exercising the datatag path and caused the generated Go identifier _, so I replaced it with the regular dash property and removed the now-unnecessary name mapping. The generated sample now compiles successfully, including go test ./... and go test -count=1 ./....

wing328 · 2026-10-05T08:12:32Z

@@ -0,0 +1,40 @@
+package openapi


i believe this file should be put in the auto-generated go client using the test spec oneof-not-enum.yaml, right?

if that's the case, please add a config similar to ./bin/configs/go-regex-test.yaml and update the go github workflow to have it tested moving forward: https://github.com/OpenAPITools/openapi-generator/blob/master/.github/workflows/samples-go-client.yaml#L12

Done. I added a dedicated oneof-not-enum Go sample config and included it in the Go client workflow paths and matrix. The runtime test is now generated into the sample as oneof-not-enum_test.go

wing328 · 2026-10-05T09:45:24Z

        return objs;
    }

+    @Override


suggestion would be nice to add more comments in the new code block (line 606 - 708)

Added concise comments around the non-obvious parts of the new logic: scoping allowed-enum checks to the affected oneOf variants, handling inherited allOf properties, and matching the case-insensitive JSON field behavior used by encoding/json.

wing328 · 2026-10-05T09:45:55Z

+        return objs;
+    }
+
+    private static Map<String, CodegenProperty> effectiveVars(CodegenModel model) {


please add docstrings to newly-created functions effectiveVars, stringEnumComparison

Added Javadocs for both effectiveVars and stringEnumComparison, describing the effective/inherited property handling and the generated string/null enum comparison behavior.

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AndreyVMarkelov · 2026-10-05T16:27:57Z

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cubic-dev-ai · 2026-10-05T16:28:03Z

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The sample on master is out of date after OpenAPITools#25064 and OpenAPITools#25089 were merged concurrently, which fails the "Samples up-to-date" check.

…#25138) * [Java][webclient/restclient/resttemplate] Simplify generated API code - Only null-check optional header, cookie and form parameters (and use braces); required parameters are already validated to be non-null - Pass the request body to invokeAPI directly instead of through a redundant postBody local variable - Use the diamond operator for generic instantiations; for anonymous ParameterizedTypeReference classes only when targeting Java 17 - Set the java17 flag for resttemplate when using Jakarta EE and use it to select the Java version in its pom.xml and build.gradle (which also removes duplicated source/target elements with Spring Boot 4) * Update stale go-oneof-not-enum sample The sample on master is out of date after #25064 and #25089 were merged concurrently, which fails the "Samples up-to-date" check.

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AndreyVMarkelov force-pushed the andreymarkelov/fix-go-not-enum branch from 21e3c5e to 74d4a3f Compare October 1, 2026 21:52

This was referenced Oct 1, 2026

[BUG][Go] String enum constraints are not enforced during JSON unmarshaling #25090

Closed

[BUG][typescript-fetch] not: enum constraints are ignored by generated type guards #25092

Closed

AndreyVMarkelov force-pushed the andreymarkelov/fix-go-not-enum branch from 74d4a3f to 5a21506 Compare October 3, 2026 17:25

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Comment thread modules/openapi-generator/src/main/resources/go/model_simple.mustache Outdated

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Comment thread modules/openapi-generator/src/test/resources/3_1/go/oneof-not-enum.yaml Outdated

AndreyVMarkelov added 6 commits October 4, 2026 09:19

fix(go): validate string enum exclusions

047bc2b

chore(go): regenerate samples

026b1dd

fix(go): align enum validation with JSON field matching

786b3a5

fix(go): validate inherited string enums

dbafad3

fix(go): preserve optional inherited JSON field tags

9d6cec6

fix(go): reuse field tags in flattened enum decoder

10b5284

AndreyVMarkelov force-pushed the andreymarkelov/fix-go-not-enum branch from 2bbd9d8 to 10b5284 Compare October 4, 2026 16:20

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fix(go): scope enum validation to affected oneOf models

c958155

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AndreyVMarkelov added 2 commits October 4, 2026 22:32

fix(go): address remaining enum validation review findings

c1b1b92

fix(go): normalize matched alias before required default

a890b52

wing328 added Client: Go Issue: Bug labels Oct 5, 2026

wing328 reviewed Oct 5, 2026

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test(go): add not-enum generated sample

c9b1d26

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Comment thread modules/openapi-generator/src/main/resources/go/model_simple.mustache

Comment thread samples/client/others/go/oneof-not-enum/model_nullable_enum_without_null_value.go

Comment thread samples/client/others/go/oneof-not-enum/model_enum_null_union.go

wing328 added this to the 7.26.0 milestone Oct 5, 2026

wing328 merged commit 9a3fb0a into OpenAPITools:master Oct 5, 2026
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ondrej-simon mentioned this pull request Oct 6, 2026

[Java][webclient/restclient/resttemplate] Simplify generated API code #25138

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wing328 commented Oct 5, 2026

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AndreyVMarkelov commented Oct 1, 2026 •

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