How to call a cloud function which is an express app?

Question

I need to call a cloud function which itself is an express app via AngularFire. If I call a "normal" function like:

BACKEND

export const myTestFunction = functions.https.onCall((data, context) => {
  return { msg: data.coolMsg.toUpperCase(), date: new Date().getTime() };
});

FRONTEND-ANGULAR

callCloudFunction() {
      const callable = this.functions.httpsCallable('myTestFunction');
      const obs = callable({ coolMsg: 'Hello backend' });
      obs.subscribe(async res => {
           console.log(res);
      });
  }

The above function gets executed properly. Now if the function is an express app, I want to call a route inside it for example: api/v1/user/profile , which will return the user profile data.

BACKEND

// main is the entire express app which you access as api/v1/<your_route>
export const api = functions.https.onRequest(main);

the express app is working properly. I have checked everything with postman.

So how should I call the route? is it possible or should I do it "manually"?

Answer 1

In this instance, you won't use the angularfire api to call your http function.
Use the HttpClientModule, inject the HttpClient service in your component constructor and call your function with an http request:

    const headers = new HttpHeaders();
    headers.append('Content-Type', 'application/json');
    const url = `/api/v1/user/profile`;
    return this.http.get(url, { headers });

Do not forget to rewrite your routes in your firebase.json to map your app and your express server to the same origin:

{
  "target": "app",
  "public": "/dist",
  "rewrites": [
     {
       "source": "/api/v1/**",  // ==> call cf for every request matching the source path
       "function": "api"
     }
  ]
}

To test it, use the firebase:emulator. It won't work with localhost using ng serve.