findAndPopulateAsync

import goods from '../controllers/goods'

export default function(app) {
    new goods(app)
}

in goods.js, we write

import proxy from '../proxy'

class Ctrl{
    constructor(app) {
        Object.assign(this, {
            app, 
            model: proxy.goods, 
        })

        this.init()
    }
       ......

then we register goods

    routes() {
        this.app.get('/api/goods/:id', this.get.bind(this))
        this.app.put('/api/goods/:id', this.put.bind(this))
    }

to get resource of specific ID, we pass in req.params.id

    get(req, res, next) {
        const params = {
            query  : {
                _id: req.params.id
            },
            fields : {}, 
            options: {}, 
        }

        const options = {
            path    : 'types', 
            select  : {}, 
        }

        this.model.findOneAndPopulateAsync(params, options)
        .then(doc => {
            if (!doc) return res.tools.setJson(1, '资源不存在或已删除')
            return res.tools.setJson(0, '调用成功', doc)
        })
        .catch(err => next(err))
    }

this.model as defined before , is proxy.goods , so we go to find implementation of

proxy.goods.findOneAndPopulateAsync

import proxy from '../proxy'

means import proxy/index.js, there we find

import goods from '../models/goods'

and in models/goods.js we see

const Schema = mongoose.Schema({
    types   : [{
        type: ObjectId, 
        ref : 'classify',
    }],
    name     : String,

})

so that findOneAndPopulateAsync must be a method
of mongoose class， let us google it

in package.json we find mongoomise

promisify mongoose by any promise library

proxy/index.js -> import RestBase from './RestBase'
-> RestBase.js -> import FeatureBase from './FeatureBase'
-> FeatureBase.js ->import bluebird from 'bluebird'

最后终于找到findAndPopulateAsync 这个函数的实现
在

FeatureBase.js

class FeatureBase{
    /**
     * 关联查询资源列表
     * @param  {Object} params  
     * @param  {Object} options 
     * @return {Function}         
     */
    findAndPopulateAsync(params = {}, options = {})

这里调用的params, options填充的什么数据呢？返回看 controllers/goods.js

        const params = {
            query  : query, 
            fields : {}, 
            options: opts, 
        }

        const options = {
            path    : 'types', 
            select  : {}, 
        }

而在该函数的实现里用到了

第1个参数的各项子属性
params.options
params.query
params.fields

第2个参数options

同样在FeatureBase.js里实现了查找某个id对应资源的方法

findOneAndPopulateAsync(params = {}, options = {})