想要在 mongodb 中获取最后 30 条收集结果记录，但不是从零开始? [英] Hot to get last 30 records of collection result in mongodb, but not from zero?

问题描述

我尝试使用 .sort({_id:1}).limit(30) 但结果它们显示从 0 到 30，而不是从 40 到 70(例如)，这意味着我看到所有消息都为 30，并且比 30 新 - 不显示.我如何从 db.collection('messages') 中找出 30 条消息?

I try to make this with .sort({_id:1}).limit(30) but in result they are showing from 0 to 30, but not from 40 to 70 (for example), that's mean i see all messages to 30, and newer than 30 - not showing. How i can find out actually 30 messages from db.collection('messages') ?

推荐答案

您可以通过调用 skip() 在光标上:

You can set the first document to be included in the results by calling skip() on the cursor:

.sort({_id: 1}).skip(40).limit(30)

将提供按_id排序后的41到70个文档.

Would provide the 41 through 70 documents after sorting by _id.

如果您想获得 最后 30 个，同时保持它们按升序排列，请反转您的排序，然后使用 Array#reverse:

If you want to get the last 30 while keeping them in ascending order, reverse your sort, and then reverse the results using Array#reverse:

coll.find().sort({_id: -1}).limit(30).toArray((err, docs) => {
    docs.reverse();    
});

这篇关于想要在 mongodb 中获取最后 30 条收集结果记录，但不是从零开始?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！