如何在Angular 9上实现MongoDB？

npm install mongodb --save

import { Injectable } from '@angular/core';
import { MongoClient, Db, Collection } from 'mongodb';

@Injectable({
  providedIn: 'root'
})
export class MongoDBService {
  private url: string = 'mongodb://localhost:27017'; // MongoDB连接URL
  private dbName: string = 'mydb'; // 数据库名称

  private client: MongoClient;
  private db: Db;

  constructor() {
    this.connect();
  }

  private async connect(): Promise<void> {
    try {
      this.client = await MongoClient.connect(this.url);
      this.db = this.client.db(this.dbName);
      console.log('Connected to MongoDB');
    } catch (error) {
      console.error('Failed to connect to MongoDB', error);
    }
  }

  public getCollection(collectionName: string): Collection {
    return this.db.collection(collectionName);
  }
}

import { Component } from '@angular/core';
import { MongoDBService } from './mongodb.service';

@Component({
  selector: 'app-root',
  template: `
    <button (click)="insertData()">Insert Data</button>
    <button (click)="queryData()">Query Data</button>
  `
})
export class AppComponent {
  constructor(private mongoDBService: MongoDBService) {}

  public async insertData(): Promise<void> {
    const collection = this.mongoDBService.getCollection('users');
    await collection.insertOne({ name: 'John', age: 30 });
    console.log('Data inserted');
  }

  public async queryData(): Promise<void> {
    const collection = this.mongoDBService.getCollection('users');
    const result = await collection.find().toArray();
    console.log('Query result:', result);
  }
}