Firebase Firestore Angular Service

db.service.ts

import { Injectable } from '@angular/core';
import {
  addDoc, collection, collectionData, CollectionReference,
  deleteDoc, doc, docData, DocumentData, DocumentReference,
  Firestore, query, QueryConstraint, setDoc, updateDoc
} from '@angular/fire/firestore';
import { Observable } from 'rxjs';

@Injectable({
  providedIn: 'root'
})
export class DbService {

  constructor(
    private firestore: Firestore
  ) { }

  // sample query constraint --> const wa:QueryConstraint[] = [where('dir','==','T'), where('day','==',23)]
  queryCollection(collectionPath: string, queryConstriants: QueryConstraint[]): Observable<DocumentData[]> {
    const collectionRef: CollectionReference<DocumentData> = collection(this.firestore, collectionPath);
    const q = query(collectionRef, ...queryConstriants);
    return collectionData(q, { idField: 'id' });
  }

  getCollection(collectionPath: string): Observable<DocumentData[]> {
    const collectionRef: CollectionReference<DocumentData> = collection(this.firestore, collectionPath);
    return collectionData(collectionRef, { idField: 'id' });
  }

  getDocument(collectionPath: string, id: string): Observable<DocumentData> {
    const documentRef = doc(this.firestore, collectionPath, id);
    return docData(documentRef, { idField: 'id' });
  }

  addDocument(collectionPath: string, data: DocumentData, id?: string): Promise<DocumentReference | void> {
    const collectionRef: CollectionReference<DocumentData> = collection(this.firestore, collectionPath);
    if (id) {
      return setDoc(doc(collectionRef, id), data, { merge: true });
    } else {
      return addDoc(collectionRef, data);
    }
  }

  deleteDocument(collectionPath: string, id: string): Promise<void> {
    const documentRef = doc(this.firestore, collectionPath, id);
    return deleteDoc(documentRef);
  }

  updateDocument(collectionPath: string, id: string, data: DocumentData): Promise<void> {
    const documentRef = doc(this.firestore, collectionPath, id);
    return updateDoc(documentRef, data);
  }
}