错误 TS2304：找不到名称“db”。 同时在 firebase 中推 object

Question

I am trying to push an object using firebase, where angular will act as frontend.
component.html

<h3>Adding an object</h3>
<input type="text" (keyup.enter)="addCourse(course)" #course>

component.ts

import { Component, OnDestroy } from '@angular/core';
import { AngularFireDatabase, AngularFireList } from 'angularfire2/database';
import { Observable, of, Subscription } from 'rxjs';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
export class AppComponent {
  title = 'FirebaseDemo';
  // courses: any[];

  courses$;
  course$;
  author$;
  todos$: AngularFireList<any>;
  // subscription : Subscription;

  constructor(db: AngularFireDatabase) {
    // code to read the courses.
    db.list('/course')
      .valueChanges()
      .subscribe((inp) => {
        this.courses$ = inp;
        console.log(this.courses$);
      });
  }
  addCourse(value: string) {
    db.list('/course/').set('4', value);
  }
}

Here the last instance of db in addCourse(value) function is throwing error called cannot find name db.
How can I access db variable out of constructor or How can I push the object in firebase?

Answer 1

Out of constructor, you can access db by using this.db. Please try the below change in you addCourse function and verify..

addCourse(value: string) {
this.db.list('/course/').set('4', value);}

Also make changes to constructor to make db public/private like:

constructor(public db: AngularFireDatabase)