fix: [MTS-3020] derive content types from OpenAPI 3.0 requestBody/response content

src/gen/js/genOperations.ts

@@ -411,6 +411,15 @@ function renderOperationInfo(
 	if (hasBody && op.contentTypes.length) {
 		lines.push(`${SP}contentTypes: ['${op.contentTypes.join("','")}'],`);
 	}
+	// Only emit `accepts` when it carries real signal (e.g. XML); JSON is the
+	// gateway default, so omitting it keeps JSON clients byte-identical.
+	if (
+		op.accepts &&
+		op.accepts.length &&
+		!(op.accepts.length === 1 && op.accepts[0] === 'application/json')
+	) {
+		lines.push(`${SP}accepts: ['${op.accepts.join("','")}'],`);
+	}
 	lines.push(`${SP}method: '${op.method}'${op.security ? ',' : ''}`);
 	if (op.security && op.security.length) {
 		const secLines = renderSecurityInfo(op.security);

src/spec/operations.ts

@@ -78,6 +78,11 @@ function getPathOperation(
 				description: op.requestBody.description || '',
 			});
 		}
+		// OpenAPI 3.0 encodes the request media type(s) under requestBody.content
+		// (Swagger 2.0 used `consumes`). Propagate them so non-JSON bodies (e.g. XML)
+		// are not defaulted to application/json downstream.
+		const requestContentTypes = Object.keys(content || {});
+		if (requestContentTypes.length) op.contentTypes = requestContentTypes;
 		delete op.requestBody;
 	}
 
@@ -92,6 +97,14 @@ function getPathOperation(
 	delete operation.consumes;
 	delete operation.produces;
 
+	// OpenAPI 3.0 encodes response media types under responses[code].content
+	// (Swagger 2.0 used `produces`). Derive the Accept header from the success
+	// responses so non-JSON responses (e.g. XML) are not defaulted to JSON.
+	if (!op.accepts || !op.accepts.length) {
+		const responseContentTypes = getResponseContentTypes(op.responses);
+		if (responseContentTypes.length) op.accepts = responseContentTypes;
+	}
+
 	if (!op.contentTypes || !op.contentTypes.length)
 		op.contentTypes = spec.contentTypes.slice();
 	if (!op.accepts || !op.accepts.length) op.accepts = spec.accepts.slice();
@@ -121,6 +134,19 @@ function getOperationResponses(op: any): ApiOperationResponse[] {
 	});
 }
 
+function getResponseContentTypes(responses: any[]): string[] {
+	const types: string[] = [];
+	for (const res of responses || []) {
+		if (!res || !res.content) continue;
+		// Only success responses inform the Accept header the client sends.
+		if (!/^2/.test(String(res.code))) continue;
+		for (const type of Object.keys(res.content)) {
+			if (!types.includes(type)) types.push(type);
+		}
+	}
+	return types;
+}
+
 function getOperationSecurity(op: any, spec: any): ApiOperationSecurity[] {
 	let security;
 

test/openapi3.yml

@@ -0,0 +1,59 @@
+openapi: 3.0.0
+info:
+  version: 1.0.0
+  title: Content Type Test
+paths:
+  /xml:
+    post:
+      operationId: xmlEcho
+      tags:
+        - ct
+      requestBody:
+        required: true
+        content:
+          application/xml:
+            schema:
+              type: string
+      responses:
+        '200':
+          description: ok
+          content:
+            application/xml:
+              schema:
+                type: string
+  /json:
+    post:
+      operationId: jsonCreate
+      tags:
+        - ct
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              type: object
+      responses:
+        '201':
+          description: created
+          content:
+            application/json:
+              schema:
+                type: object
+  /mixed:
+    post:
+      operationId: jsonReqXmlResp
+      tags:
+        - ct
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              type: object
+      responses:
+        '200':
+          description: ok
+          content:
+            application/xml:
+              schema:
+                type: string

test/spec/operations.spec.ts

@@ -24,4 +24,34 @@ describe('operations', () => {
 		const resDefault = listPets.responses.find((res) => res.code === 'default');
 		expect(resDefault).not.toBeFalsy();
 	});
+
+	describe('OpenAPI 3.0 content types', () => {
+		let operations: any[];
+		beforeAll(async () => {
+			const spec = await resolveSpec(`${__dirname}/../openapi3.yml`);
+			operations = getOperations(spec);
+		});
+
+		it('derives request contentTypes from requestBody.content (XML)', () => {
+			const op = operations.find((o) => o.id === 'xmlEcho');
+			expect(op.contentTypes).toEqual(['application/xml']);
+		});
+
+		it('derives accepts from the success response content (XML)', () => {
+			const op = operations.find((o) => o.id === 'xmlEcho');
+			expect(op.accepts).toEqual(['application/xml']);
+		});
+
+		it('keeps JSON request/response as application/json', () => {
+			const op = operations.find((o) => o.id === 'jsonCreate');
+			expect(op.contentTypes).toEqual(['application/json']);
+			expect(op.accepts).toEqual(['application/json']);
+		});
+
+		it('derives request and response content types independently', () => {
+			const op = operations.find((o) => o.id === 'jsonReqXmlResp');
+			expect(op.contentTypes).toEqual(['application/json']);
+			expect(op.accepts).toEqual(['application/xml']);
+		});
+	});
 });