[AngularFire2] Build a Custom Node Backend Using Firebase Queue

In this lesson we are going to learn how to build a custom Node process for batch processing of Firebase data using the Firebase queue library.

From UI, we create a request to add ‘queue/tasks‘ node in database which contains the data to be deleted by queue later.

Controller:

  requestLessonDeletion() {
    this.courseService.deleteLEssonById(
      this.lesson.$key,
      this.lesson.courseId
    )
      .then(() => alert("lesson delete successfully"))
      .catch((err) => console.error(err));
  }

Service:

this.rootDb = fb.database().ref()  

...

deleteLEssonById(lessonId: string, courseId) {
    return this.rootDb.child(‘queue/tasks‘)
      .push({
        lessonId,
        courseId
      })
  }

Then we will build a node server to do the deletion:

package.json:

"batch-server": "./node_modules/.bin/ts-node ./batch-server.ts",

Install:

npm install --save-dev ts-promise firebase-queue

import {firebaseConfig} from "./src/environments/firebase.config";
import {initializeApp, auth,database} from ‘firebase‘;
const Queue = require(‘firebase-queue‘);
import Promise from "ts-promise";

console.log(‘Running batch server ...‘);

initializeApp(firebaseConfig);

auth()
  .signInWithEmailAndPassword(‘[email protected]‘, ‘youdon‘tknow‘)
  .then(runConsumer)
  .catch(onError);

function onError(err) {
  console.error("Could not login", err);
  process.exit();
}

function runConsumer() {

  console.log("Running consumer ...");

  const lessonsRef = database().ref("lessons");
  const lessonsPerCourseRef = database().ref("lessonsPerCourse");

  const queueRef = database().ref(‘queue‘);

  const queue = new Queue(queueRef, function(data, progress, resolve, reject) {

    console.log(‘received delete request ...‘,data);

    const deleteLessonPromise = lessonsRef.child(data.lessonId).remove();

    const deleteLessonPerCoursePromise =
      lessonsPerCourseRef.child(`${data.courseId}/${data.lessonId}`).remove();

    Promise.all([deleteLessonPromise, deleteLessonPerCoursePromise])
      .then(
        () => {
          console.log("lesson deleted");
          resolve();
        }
      )
      .catch(() => {
        console.log("lesson deletion in error");
        reject();
      });
  });
}

Run ‘npm run batch-server‘, then the data inside "lessons" & "lessonsPreCourse" & "queue/tasks" will all be deleted.

{
  "rules": {
    ".read": "auth != null",
    ".write": "auth != null",
      "courses": {
        ".indexOn": ["url"]
       },
    "lessons": {
      ".indexOn": ["url"]
    },
      "queue": {
        "tasks": {
          ".indexOn": ["_state"]
        }
      }
  }
}

Need to add "queue" to the firebase ruels to get rid of error message.

Github