Don't attempt to json encode string types

packages/cli/src/routeGeneration/templates/express.hbs

@@ -208,6 +208,9 @@ export function RegisterRoutes(app: Router) {
         if (data && typeof data.pipe === 'function' && data.readable && typeof data._read === 'function') {
             response.status(statusCode || 200)
             data.pipe(response);
+        } else if (data && typeof data === 'string') {
+            response.type('txt');
+            response.status(statusCode || 200).send(data);
         } else if (data !== null && data !== undefined) {
             response.status(statusCode || 200).json(data);
         } else {

packages/cli/src/routeGeneration/templates/hapi.hbs

@@ -298,7 +298,6 @@ export function RegisterRoutes(server: any) {
         if (h.__isTsoaResponded) {
             return h.__isTsoaResponded;
         }
-
         let response = data !== null && data !== undefined
                     ? h.response(data).code(200)
                     : h.response("").code(204);
@@ -307,6 +306,10 @@ export function RegisterRoutes(server: any) {
             response.header(name, headers[name]);
         });
 
+        if (data && typeof data == 'string') {
+            response.header('content-type', 'text/plain');
+        }
+
         if (statusCode) {
             response.code(statusCode);
         }

tests/fixtures/controllers/getController.ts

@@ -308,6 +308,11 @@ export class GetTestController extends Controller {
     return new ModelService().getModel();
   }
 
+  @Get('StringValue')
+  public async getStringValue(): Promise<string> {
+    return 'FOO';
+  }
+
   @Get('IndexedValue')
   public async getIndexedValue(): Promise<IndexedValue> {
     return 'FOO';

tests/integration/express-server.spec.ts

@@ -244,6 +244,15 @@ describe('Express Server', () => {
     });
   });
 
+  it('returns string responses', () => {
+    return verifyGetRequest(`${basePath}/GetTest/StringValue`, (_err, res) => {
+      expect(res.status).to.equal(200);
+      expect(res.headers['content-type']).to.equal('text/plain; charset=utf-8');
+      expect(res.text).to.equal('FOO');
+      return;
+    });
+  });
+
   it('should reject invalid additionalProperties', () => {
     const invalidValues = ['invalid', null, [], 1, { foo: null }, { foo: 1 }, { foo: [] }, { foo: {} }, { foo: { foo: 'bar' } }];
 

tests/integration/hapi-server.spec.ts

@@ -48,6 +48,14 @@ describe('Hapi Server', () => {
     });
   });
 
+  it('returns string responses', () => {
+    return verifyGetRequest(`${basePath}/GetTest/StringValue`, (_err, res) => {
+      expect(res.get('content-type')).to.eq('text/plain; charset=utf-8');
+      expect(res.text).to.equal('FOO');
+      return;
+    });
+  });
+
   it('can handle get request with collection return value', () => {
     return verifyGetRequest(basePath + '/GetTest/Multi', (_err, res) => {
       const models = res.body as TestModel[];

tests/integration/koa-server.spec.ts

@@ -59,6 +59,14 @@ describe('Koa Server', () => {
     });
   });
 
+  it('returns string responses', () => {
+    return verifyGetRequest(`${basePath}/GetTest/StringValue`, (_err, res) => {
+      expect(res.header['content-type']).to.equal('text/plain; charset=utf-8');
+      expect(res.text).to.equal('FOO');
+      return;
+    });
+  });
+
   it('can handle get request with path and query parameters', () => {
     return verifyGetRequest(basePath + `/GetTest/${1}/true/test?booleanParam=true&stringParam=test1234&numberParam=1234`, (_err, res) => {
       const model = res.body as TestModel;