fix(python): missing field_validator import for UUID properties with pattern

[timonrieger]

When an OpenAPI schema property has both format: uuid and a pattern constraint, the Python client generator emits a @field_validator decorator in the generated model but fails to add the corresponding from pydantic import field_validator import. This causes a NameError at runtime.

Root cause: In AbstractPythonCodegen, the PydanticType.fromCommon() type dispatch is an exclusive if/else chain. UUID is checked before string, so uuidType() is called (which doesn't handle patterns) and stringType() (which adds the field_validator import for patterns) is never reached. Meanwhile, the mustache template emits @field_validator based on the x-regex vendor extension, which is set independently for any property with a pattern.

Fix: Add a type-independent pattern != null check in fromCommon() before the type dispatch, ensuring field_validator is imported for any property type that has a pattern constraint.

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cc @cbornet (2017/09) @tomplus (2018/10) @krjakbrjak (2023/02) @fa0311 (2023/10) @multani (2023/10)

---

Summary by cubic

Fix missing pydantic field_validator import in generated Python models when a UUID property also has a pattern, preventing a runtime NameError.

• Bug Fixes
  • Always import field_validator when a property has a pattern, regardless of type (added check in fromCommon).
  • Added a test with a UUID + pattern schema to confirm the import is present.

^{Written for commit c666f03. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 3 files

[timonrieger]

alternatively, to be less defensive and only apply that to UUID types instead of all types with regex pattern

private PythonType uuidType(IJsonSchemaValidationProperties cp) {
    moduleImports.add("uuid", "UUID");
    if (cp.getPattern() != null) {
        moduleImports.add("pydantic", "field_validator");
    }
    return new PythonType("UUID");
}