title: Mongoose.js - population and additional fields?
body: <p>I want to add some additional data to <strong>UserModel</strong> like <strong>watchedMovies</strong> and I have following schema:</p>
  
  <pre><code>let userSchema = new Schema({
    watchedMovies: [{
      type: Schema.Types.ObjectId,
      ref: 'Movie'
    }]
  })
  </code></pre>
  
  <p>and:</p>
  
  <pre><code>let movieSchema = new Schema({
    title: String
  })
  </code></pre>
  
  <p>I was wondering is it possible to add any additional fields to <strong>watchedMovies</strong> object and store it along with ObjectId? I would like to add <strong>watchedAt</strong> date so when I'm populating <strong>watchedMovies</strong> with <code>UserModel.find().populate('watchedMovies', 'title').exec(...)</code> I would get something like:</p>
  
  <pre><code>{
    _id: ObjectId(UserId),
    watchedMovies: [{
      _id: ObjectId(...),
      title: 'Some title',
      watchedAt: TimeStamp
    }]
  }
  </code></pre>
  
  <p><strong>watchedAt</strong> attribute specifies when (Date object) reference was added to UserModel</p>
  
  <p><strong>Is it possible with mongoose and how should I change my schema?</strong></p>
  
  <p>Thank You</p>