mongodb:更新元素? [英] mongodb: updating elements?

问题描述

我(和大多数人一样)来自 mySQL 背景，试图切换到 noSQL 和 mongoDB.由于非规范化是 noSQL 的一部分，因为连接是不可能的，所以我将如何设计一个简单的博客:

I am (as most ) coming from a mySQL background trying to switch over to noSQL and mongoDB. Since denormalization is a part of noSQL since joins is impossible, here's how I would design a simple blog:

array (
    blog_title => 'my blogpost',
    'date' => '2010-09-05',
    comments => array (
        '1' => 'Such a good post!!! You deserve a nobel prize'
    )
);

如果我想更新评论，在该数组中添加一个新元素，如果多个用户同时尝试撰写评论，我如何确保完成此操作而不是覆盖整个评论数组?

If I want to update the comments, adding a new element in that array, how can I make sure that this is done and not the whole comments array being overwritten if multiple users are trying to write a comment at the same time?

是我在 mongoDB 中处理的 push 函数吗?

Is it the push function I am looking after in mongoDB?

推荐答案

正确，$push 运算符允许您更新现有数组.您可以使用 $pushAll运算符在单个查询中添加多个值.

Correct, the $push operator allows you to update an existing array. You can use the $pushAll operator to add multiple values in a single query.

要向示例文档添加评论，查询将是:

To add a comment to your example document, the query would be:

db.posts.update({blog_title: "my blogpost"}, {$push: {comments: "New comment"}})

这些操作符是原子的，因此如果多个用户同时添加评论，您不会遇到任何问题.

These operators are atomic, so you won't run into any problems if multiple users add comments simultaneously.

这篇关于mongodb:更新元素?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！