feat: add handler builder to support ioc

lib/createHandler.ts

@@ -9,6 +9,7 @@ import { parseRequestUrl } from './internals/parseRequestUrl';
  * Prepares a router for the given class.
  *
  * @param cls Router class
+ * @param builder Router instance builder
  *
  * @example
  * ```ts
@@ -24,15 +25,22 @@ import { parseRequestUrl } from './internals/parseRequestUrl';
  * export default createHandler(Events);
  * ```
  */
-export function createHandler(cls: new (...args: any[]) => any): NextApiHandler {
-  const instance = new cls();
+export function createHandler<T extends any>(
+  cls: new (...args: any[]) => T,
+  builder: () => T | Promise<T> = () => new cls()
+): NextApiHandler {
+  let instance: any;
   const [directory, fileName] = getCallerInfo();
 
-  return (req: NextApiRequest, res: NextApiResponse) => {
+  return async (req: NextApiRequest, res: NextApiResponse) => {
     if (!req.url || !req.method) {
       return notFound(req, res);
     }
 
+    if (!instance) {
+      instance = await builder();
+    }
+
     const path = parseRequestUrl(req, directory, fileName);
     const [keys, match, method] = findRoute(cls, req.method, path);
     if (!method) {

package.json

@@ -69,6 +69,7 @@
     "express": "^4.17.1",
     "express-rate-limit": "^6.0.4",
     "husky": "8.0.3",
+    "inversify": "5.1.1",
     "jest": "26.6.3",
     "lint-staged": "13.1.0",
     "multer": "^1.4.2",

test/e2e-ioc.test.ts

@@ -0,0 +1,56 @@
+import 'reflect-metadata';
+import { Container, injectable } from 'inversify';
+import request from 'supertest';
+import { createHandler, Get } from '../lib';
+import { setupServer } from './setupServer';
+
+// Create service
+const container = new Container({
+  autoBindInjectable: true
+});
+
+interface TestData {
+  test: string;
+}
+
+@injectable()
+export class TestService {
+  public getTest(): TestData {
+    return {
+      test: 'successful'
+    };
+  }
+}
+
+// Create handler with injection
+@injectable()
+class TestHandler {
+  public constructor(private readonly service: TestService) {}
+
+  @Get()
+  public testData() {
+    return this.service.getTest();
+  }
+}
+
+describe('E2E - ioc', () => {
+  let server: ReturnType<typeof setupServer>;
+  beforeAll(() => (server = setupServer(createHandler(TestHandler, () => container.get(TestHandler)))));
+  afterAll(() => {
+    if ('close' in server && typeof server.close === 'function') {
+      server.close();
+    }
+  });
+
+  it('Should successfully return data from service', () =>
+    request(server)
+      .get('/')
+      .expect(200)
+      .then(res =>
+        expect(res).toMatchObject({
+          body: {
+            test: 'successful'
+          }
+        })
+      ));
+});

yarn.lock

@@ -4264,6 +4264,11 @@ into-stream@^6.0.0:
     from2 "^2.3.0"
     p-is-promise "^3.0.0"
 
+[email protected]:
+  version "5.1.1"
+  resolved "https://registry.yarnpkg.com/inversify/-/inversify-5.1.1.tgz#6fbd668c591337404e005a1946bfe0d802c08730"
+  integrity sha512-j8grHGDzv1v+8T1sAQ+3boTCntFPfvxLCkNcxB1J8qA0lUN+fAlSyYd+RXKvaPRL4AGyPxViutBEJHNXOyUdFQ==
+
 ip-regex@^4.1.0:
   version "4.3.0"
   resolved "https://registry.yarnpkg.com/ip-regex/-/ip-regex-4.3.0.tgz#687275ab0f57fa76978ff8f4dddc8a23d5990db5"