fix(utils): 🐛 Handle single-element oneOf without union

Author: adrianhdezm

src/utils/json-schema-to-typed-dict.ts

@@ -97,6 +97,9 @@ export function convertToTypedDict(name: string, schema: OpenAPI.SchemaObject |
         typingImports.add('Any');
         return 'Any';
       }
+      if (s.oneOf.length === 1) {
+        return toType(s.oneOf[0] as any, className);
+      }
       typingImports.add('Union');
       const parts = s.oneOf.map((sub, idx) => toType(sub as any, `${className}Option${idx}`)).join(', ');
       return `Union[${parts}]`;
@@ -107,6 +110,9 @@ export function convertToTypedDict(name: string, schema: OpenAPI.SchemaObject |
         typingImports.add('Any');
         return 'Any';
       }
+      if (s.anyOf.length === 1) {
+        return toType(s.anyOf[0] as any, className);
+      }
       typingImports.add('Union');
       const parts = s.anyOf.map((sub, idx) => toType(sub as any, `${className}Option${idx}`)).join(', ');
       return `Union[${parts}]`;

src/utils/json-schema-to-zod.ts

@@ -33,6 +33,9 @@ export function convertSchema(schema: OpenAPI.SchemaObject | OpenAPI.ReferenceOb
       if (items.length === 0) {
         return 'z.any()';
       }
+      if (items.length === 1) {
+        return walk(items[0]!);
+      }
       const parts = items.map((sub) => walk(sub)).join(', ');
       return `z.union([${parts}])`;
     }
@@ -42,6 +45,9 @@ export function convertSchema(schema: OpenAPI.SchemaObject | OpenAPI.ReferenceOb
       if (items.length === 0) {
         return 'z.any()';
       }
+      if (items.length === 1) {
+        return walk(items[0]!);
+      }
       const parts = items.map((sub) => walk(sub)).join(', ');
       return `z.union([${parts}])`;
     }

tests/__snapshots__/json-schema-to-typed-dict.spec.ts.snap

@@ -39,6 +39,11 @@ class Place(TypedDict, total=False):
     location: Required[PlaceLocation]"
 `;
 
+exports[`generate-python-dict > handles oneOf with a single ref 1`] = `
+"from typing import TypedDict
+MessageSingle = A"
+`;
+
 exports[`generate-python-dict > handles oneOf with refs 1`] = `
 "from typing import TypedDict, Union
 Message = Union[A, B]"

tests/json-schema-to-typed-dict.spec.ts

@@ -126,6 +126,29 @@ describe('generate-python-dict', () => {
     expect(content).toMatchSnapshot();
   });
 
+  it('handles oneOf with a single ref', () => {
+    const doc: OpenAPI.Document = {
+      openapi: '3.1.0',
+      info: { title: 't', version: '1' },
+      paths: {},
+      components: {
+        schemas: {
+          A: { type: 'object', properties: { id: { type: 'string' } } },
+          MessageSingle: { oneOf: [{ $ref: '#/components/schemas/A' }] }
+        }
+      }
+    };
+    const schemas = extractSchemas(doc, null);
+    const { definition, typingImports } = convertToTypedDict('MessageSingle', schemas.MessageSingle as OpenAPI.SchemaObject);
+    const typingLine = `from typing import ${Array.from(typingImports).join(', ')}`;
+    const content = [typingLine, '', definition, ''].filter(Boolean).join('\n');
+    const tmp = path.join(__dirname, 'tmp_oneof_single.py');
+    fs.writeFileSync(tmp, content);
+    child_process.execSync(`python3 -m py_compile ${tmp}`);
+    fs.unlinkSync(tmp);
+    expect(content).toMatchSnapshot();
+  });
+
   it('handles inline object properties', () => {
     const doc: OpenAPI.Document = {
       openapi: '3.1.0',

tests/json-schema-to-zod.spec.ts

@@ -63,6 +63,15 @@ describe('convertSchema', () => {
     expect(imports.has('B')).toBe(true);
   });
 
+  it('handles oneOf with a single ref', () => {
+    const schema = {
+      oneOf: [{ $ref: '#/components/schemas/A' }]
+    } as OpenAPI.SchemaObject;
+    const { zodString, imports } = convertSchema(schema);
+    expect(zodString).toBe('A');
+    expect(imports.has('A')).toBe(true);
+  });
+
   it('converts inline object properties', () => {
     const schema = {
       type: 'object',