How to use mongodb

disconnect() {
  if (this.client) {
   this.client.close();
  }
 }

deleteFile(filename) {
  return this._connect().then(database => {
   const gridStore = new _mongodb.GridStore(database, filename, 'r');
   return gridStore.open();
  }).then(gridStore => {
   return gridStore.unlink();
  }).then(gridStore => {
   return gridStore.close();
  });
 }

handleShutdown() {
  if (!this._client) {
   return Promise.resolve();
  }

  return this._client.close(false);
 }

it('auto-escapes symbols in auth information', () => {
  spyOn(MongoClient, 'connect').and.returnValue(Promise.resolve(fakeClient));
  new MongoStorageAdapter({
   uri:
    'mongodb://user!with@+ symbols:password!with@+ symbols@localhost:1234/parse',
  }).connect();
  expect(MongoClient.connect).toHaveBeenCalledWith(
   'mongodb://user!with%40%2B%20symbols:password!with%40%2B%20symbols@localhost:1234/parse',
   jasmine.any(Object)
  );
 });

// Use connect method to connect to the Server
setTimeout(() => {
 client.connect(function(err) {
  if (err) {
   return console.error(err);
  }
  console.log("Connected successfully to database");
  db = client.db(MONGO_DATABASE_NAME);
 });
}, 2000);

app.post('/collect', (req, res) => {
 console.log(req.body);
 const client = new MongoClient(process.env.MONGO_URL);
 client.connect((err) => {
  const db = client.db();
  const collection = db.collection('events');
  collection.insertOne({ timestamp: new Date(), ...req.body }, ((err, result) => {
   client.close();
   res.send('ok');
  }));
 });
});

async deleteFile(filename: string) {
  const bucket = await this._getBucket();
  const documents = await bucket.find({ filename }).toArray();
  if (documents.length === 0) {
   throw new Error('FileNotFound');
  }
  return Promise.all(
   documents.map((doc) => {
    return bucket.delete(doc._id);
   })
  );
 }

beforeEach(async () => {
  const gsAdapter = new GridStoreAdapter(databaseURI);
  const db = await gsAdapter._connect();
  await db.dropDatabase();
 });

it('properly overrides files', async () => {
  const gfsAdapter = new GridFSBucketAdapter(databaseURI);
  await gfsAdapter.createFile('myFileName', 'a simple file');
  await gfsAdapter.createFile('myFileName', 'an overrided simple file');
  const data = await gfsAdapter.getFileData('myFileName');
  expect(data.toString('utf8')).toBe('an overrided simple file');
  const bucket = await gfsAdapter._getBucket();
  const documents = await bucket.find({ filename: 'myFileName' }).toArray();
  expect(documents.length).toBe(2);
  await gfsAdapter.deleteFile('myFileName');
  await expectMissingFile(gfsAdapter, 'myFileName');
 });

_connect() {
  if (!this._connectionPromise) {
   this._connectionPromise = MongoClient.connect(
    this._databaseURI,
    this._mongoOptions
   ).then((client) => {
    this._client = client;
    return client.db(client.s.options.dbName);
   });
  }
  return this._connectionPromise;
 }

async getMetadata(filename) {
  const bucket = await this._getBucket();
  const files = await bucket.find({ filename }).toArray();
  if (files.length === 0) {
   return {};
  }
  const { metadata } = files[0];
  return { metadata };
 }

// For a given config object, filename, and data, store a file
 // Returns a promise


 createFile(filename, data) {
  return this._connect().then(database => {
   const gridStore = new _mongodb.GridStore(database, filename, 'w');
   return gridStore.open();
  }).then(gridStore => {
   return gridStore.write(data);
  }).then(gridStore => {
   return gridStore.close();
  });
 }

handleShutdown() {
  if (!this._client) {
   return Promise.resolve();
  }
  return this._client.close(false);
 }

handleShutdown() {
  if (!this._client) {
   return Promise.resolve();
  }
  return this._client.close(false);
 }

_connect() {
  if (!this._connectionPromise) {
   this._connectionPromise = MongoClient.connect(
    this._databaseURI,
    this._mongoOptions
   ).then(client => {
    this._client = client;
    return client.db(client.s.options.dbName);
   });
  }
  return this._connectionPromise;
 }