import { Injectable } from '@angular/core' ; import { Observable , of } from 'rxjs' ; @ Injectable ( ) export abstract class DbService { constructor ( ) { } public createDoc ( collectionName , document ) { } public CreateDocWithoutDocID ( collectionName , document ) { } public setDoc ( collectionName , docId , document , timeStamp ? ) { } public updateDoc ( collectionName , docId , document ) { } public valueChanges ( collectionName , path ? , queryParams ? ) { return of ( ) ; } public createId ( ) { } public getFireStorageReference ( filePath ) { } public getFireStore ( ) { } public getDoc ( collectionName , docId ) { } public upload ( filePath , imageBlob ) { } public deleteDoc ( collectionName , docId ) { } }