Mongoose聚合时忽略空字段

const mongoose = require('mongoose');

const Schema = mongoose.Schema;

// 创建Schema
const mySchema = new Schema({
  name: String,
  age: Number,
  address: String
});

// 创建Model
const MyModel = mongoose.model('MyModel', mySchema);

// 聚合操作
MyModel.aggregate([
  {
    $match: {
      address: { $exists: true } // 忽略空字段
    }
  },
  {
    $group: {
      _id: '$name',
      totalAge: { $sum: '$age' }
    }
  }
])
.then(result => {
  console.log(result);
})
.catch(error => {
  console.error(error);
});