console.log是否省略了一些密钥对？

I'm debugging a NodeJS app where mongodb is being used.

When I console.log keys of a JS object (say booking) using console.log( Object.keys(booking) ) statement, it prints:

[
  '$__',     'isNew',
  'errors',  '_doc',
  '$locals', '$op',
  '$init'
]

But When I directly print the same object using console.log(booking) statement, it prints:

{
  _id: 5eb4fef797bf1e29986e333f,
  user: 5eb413c78a84bc63f0ef83d4,
  event: {
    _id: 5eb4182c45d25b4c981a21ce,
    title: 'Test Event',
    description: 'bla bla bla',
    price: 99.99,
    date: 'Wed Jan 01 2020 05:45:00 GMT+0545',
    creator: 5eb413c78a84bc63f0ef83d4,
    __v: 0
  },
  createdAt: 2020-05-08T06:40:55.905Z,
  updatedAt: 2020-05-08T06:40:55.905Z,
  __v: 0
}

Now if you notice, some keys are missing both times I do console.log. I have no idea what the hell is going on. WHY is that happening?

I'm also using mongoose models. My code is like this:

Booking.findById({_id: args.bookingID}).populate('event').then(booking => {
    console.log( booking )
    console.log( Object.keys(booking) )
});

请询问您是否需要更多信息。

任何帮助将不胜感激 ：）