MongoDB正则表达式匹配问题 [英] MongoDB regex matching trouble

问题描述

这是我的MongoDB Shell会话；

Here is my MongoDB shell session;

> db.foo.save({path: 'a:b'})
WriteResult({ "nInserted" : 1 })

> db.foo.findOne()
{ "_id" : ObjectId("58fedc47622e89329d123ee8"), "path" : "a:b" }

> db.foo.save({path: 'a:b:c'})
WriteResult({ "nInserted" : 1 })

> db.foo.find({path: /a:[^:]+/})
{ "_id" : ObjectId("58fedc47622e89329d123ee8"), "path" : "a:b" }
{ "_id" : ObjectId("58fedc57622e89329d123ee9"), "path" : "a:b:c" }

> db.foo.find({path: /a:[a-z]+/})
{ "_id" : ObjectId("58fedc47622e89329d123ee8"), "path" : "a:b" }
{ "_id" : ObjectId("58fedc57622e89329d123ee9"), "path" : "a:b:c" }

很显然，正则表达式/a:[^:]+/和/a:[a-z]+/不应与字符串'a:b:c'匹配，但看起来Mongo在此正则表达式上失败了，有人知道这里发生了什么吗?

Clearly the regex /a:[^:]+/ and /a:[a-z]+/ shouldn't match string 'a:b:c', but looks like Mongo failed on this regex, does anyone know what happened here?

它已作为Bug票证提交给MongoDB Jira， MongoDB查询结构中的错误?

It was submitted to MongoDB Jira, as a bug ticket, so is it a bug within MongoDB querying structure?

推荐答案

问题在于部分匹配，因为您没有限制整个单词的正则表达式，所以a:b:c中存在的部分匹配就是会导致您获得该文档.

The trouble is with the partial matching, since you are not restricting the regex for the whole word, the partial match that exists in a:b:c that is a:b is resulting in you getting that document.

将下面的正则表达式与^$一起使用，它们是表示单词开头和结尾的锚点；

Use the following regex with ^$ that are anchors to represent beginning and the end of the word;

db.foo.find({path: /^a:[^:]+$/})
db.foo.find({path: /^a:[a-z]+$/})

这将使正则表达式适用于整个字符串，并忽略上述部分匹配.有关正则表达式锚点的更多信息，请单击此处.

This will make the regex apply for the whole string, and ignore the partial matches as explained above. For more on regex anchors, click here.

因此，总而言之，没有错误，只是正则表达式的误用.

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