populate and select mongoose code example

Example 1: mongoos populate a ref

const storySchema = Schema({
  authors: [{ type: Schema.Types.ObjectId, ref: 'Person' }],
  title: String
});

// Later

const story = await Story.findOne({ title: 'Casino Royale' }).populate('authors');
story.authors; // `[]`

Example 2: populate mongoose array select

User.findById(id).populate({
    path: 'contacts.user',
    select: 'email'
})