将范围传递给db.collection.group

是否有可能传递一个全局上下文db.collection.group的keyf ？

 {MongoClient} = require 'mongodb' GLOBAL_VAR = 1 reducer = (obj, prev) -> prev.count += GLOBAL_VAR initial = {count:0} MongoClient.connect 'mongodb://localhost:27017/test', (err, db) -> throw err if err db.collection('orders').group [], {}, initial, reducer, (err, result) -> throw err if err console.log result 

我得到以下错误

 MongoError: exception: ReferenceError: GLOBAL_VAR is not defined at $group reduce setup:2 

Answer 1

你可以通过variables作为初始状态

 {MongoClient} = require 'mongodb' GLOBAL_VAR = 1 reducer = (obj, prev) -> prev.count += prev.GLOBAL_VAR initial = {count: 0, GLOBAL_VAR} MongoClient.connect 'mongodb://localhost:27017/test', (err, db) -> throw err if err db.collection('orders').group [], {}, initial, reducer, (err, result) -> throw err if err console.log result