UnhandledPromiseRejectionWarning: TypeError: con.db is not a function connect-mongo 连接数据库方法

// Basic usage
app.use(session({
  store: MongoStore.create({ mongoUrl: 'mongodb://localhost/test-app' })
}));

// Advanced usage
app.use(session({
  store: MongoStore.create({
    mongoUrl: 'mongodb://user12345:foobar@localhost/test-app?authSource=admin&w=1',
    mongoOptions: advancedOptions // See below for details
  })
}));

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