如何使用mongoose填充嵌套数组

npm install mongoose

const mongoose = require('mongoose');

const parentSchema = new mongoose.Schema({
  name: String,
  children: [{
    type: mongoose.Schema.Types.ObjectId,
    ref: 'Child'
  }]
});

const childSchema = new mongoose.Schema({
  name: String
});

const Parent = mongoose.model('Parent', parentSchema);
const Child = mongoose.model('Child', childSchema);

const child1 = new Child({ name: 'Child 1' });
const child2 = new Child({ name: 'Child 2' });

const parent = new Parent({ 
  name: 'Parent',
  children: [child1, child2]
});

child1.save();
child2.save();

parent.save();

Parent.findOne({ name: 'Parent' })
  .populate('children')
  .exec((err, populatedParent) => {
    if (err) {
      console.error(err);
    } else {
      console.log(populatedParent);
    }
  });