如何使用猫鼬填充2个模型的mongodb？

Question

我有2个MODELS（不是模型和非模型模式）。

例如：

model1.js

const mongoose = require('mongoose')

const model1Schema = new mongoose.Schema({
    serviceCenterId: {type: mongoose.Schema.ObjectId, required: true}, 
    testId: {type: mongoose.Schema.ObjectId, required: true}
    somethingElse: {...} 
}, {timestamps: true})


module.exports = mongoose.model('Model1', model1Schema);

models2.js

const mongoose = require('mongoose')

const model2Schema = new mongoose.Schema({
    //id of serviceCenterId is same as the MODEL1's serviceCenterId
    //testId , same as testId of MODEL1
    serviceCenterId: {type: mongoose.Schema.ObjectId, required: true},
    testId: {type: mongoose.Schema.ObjectId, required: true},
    //dummy datas....
}, {timestamps: true})

module.exports = mongoose.model('Model2', model2Schema);

我想在查询Model1时填充Model2（这些是模型，而不仅仅是模式）。 最好的方法是什么？