node.js更新mongodb数组字段可以参考官方指南
http://docs.mongodb.org/manual/reference/operator/update/positional/#up._S_
提供一个小的案例代码:
var conditions = {_id: suggestID,"replies":{ $elemMatch:{rid:rid,replyname:'1100100'}}};
var update = {$set: {"replies.$.replycontent": replynewcontent,"replies.$.reply_at":new Date()}};
SuggestMongooseModel.findOneAndUpdate(conditions, update, {upsert: false}, function (err, suggest) {
。。。。。。
});