Fix OpenAPI enum schema for non-body parameters with naming policy

[mikekistler]

Summary

Fixes #65026

When a global JsonStringEnumConverter with a naming policy (e.g. KebabCaseLower) is configured via ConfigureHttpJsonOptions, the OpenAPI spec can emit naming-policy-transformed enum values (e.g. my-value) for non-body parameters. However, query/path/header/form parameter binding use Enum.TryParse, which only accepts the original C# member names (e.g. MyValue). This causes clients following the spec to send values that the server rejects with 400.

Changes

JsonNodeSchemaExtensions.ApplyParameterInfo — For non-body enum parameters (query, path, header, and form), replaces the naming-policy-transformed enum values with Enum.GetNames() so the schema matches what Enum.TryParse accepts.

OpenApiSchemaService.GetOrCreateSchemaAsync — When a naming policy transforms enum values, skips schema componentization for non-body enum parameters and returns an inline schema instead. This prevents the shared component (which retains naming-policy values for body serialization) from overwriting the corrected parameter schema.

These two changes work together so that:

• Query/path/header/form params show PascalCase enum values (matching Enum.TryParse behavior)
• Body params/responses keep naming-policy-transformed values (matching JSON serialization)
• Enums with attribute-level converters (no global naming policy) are unaffected

Tests

• GetOpenApiParameters_EnumWithGlobalNamingPolicy_UsesOriginalMemberNames — verifies query param enum values are PascalCase when a global KebabCaseLower policy is configured
• GetOpenApiParameters_EnumWithGlobalNamingPolicy_HandlesQueryAndBodyUsage — verifies the same enum type produces PascalCase for query params and kebab-case for body responses
• GetOpenApiRequestBody_EnumFormFieldWithGlobalNamingPolicy_UsesOriginalMemberNames — verifies [FromForm] enum values stay in their original C# member form

All 222 OpenApiSchemaServiceTests pass.

[Copilot]

Pull request overview

Fixes an OpenAPI/spec mismatch where global JsonStringEnumConverter naming policies were being applied to non-body parameters (query/path/header), even though runtime binding uses Enum.TryParse and only accepts the original C# enum member names.

Changes:

• Adjust enum parameter schemas for non-body parameters to emit original enum member names.
• Avoid schema componentization for affected non-body enum parameters to prevent shared component schemas (used for body serialization) from overwriting corrected parameter schemas.
• Add tests covering query-parameter enums with a global naming policy, including mixed query + response usage of the same enum.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Shared/SharedTypes.cs	Adds a new test enum (Priority) used for global-naming-policy scenarios.
src/OpenApi/test/Microsoft.AspNetCore.OpenApi.Tests/Services/OpenApiSchemaService/OpenApiSchemaService.ParameterSchemas.cs	Adds coverage ensuring query parameter enums use original member names while response bodies keep naming-policy output.
src/OpenApi/src/Services/Schemas/OpenApiSchemaService.cs	Skips componentization for affected non-body enum parameters when naming policy transforms enum values.
src/OpenApi/src/Extensions/JsonNodeSchemaExtensions.cs	Rewrites enum values for applicable parameter schemas to match Enum.TryParse expectations.

[BrennanConroy]

Do we also need to consider the default/x-ref-default values that will still be kebab-case?

[BrennanConroy]

Are the enum values always going to line up with the member names if they are the 'correct' case already?

[BrennanConroy]

AI doesn't like this as there might be a count mismatch if names have the same value. e.g. enum E { A = 0, B = 1, C = 1} It says schema generation usually collapses duplicate values so you'd get ["A", "B"] but be comparing against ["A", "B", "C"].

I'm not sure how true that is, but we might want to test and handle that?

[dotnet-policy-service]

Looks like this PR hasn't been active for some time and the codebase could have been changed in the meantime.
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