如何查找文档，哪个字段是特定字符串的子字符串？ [英] How to find documents, which field is a substring to the specific string?

问题描述

有什么方法可以在MongoDB集合中找到文档，哪个字段是我的 string 的子字符串？

Is there any way to find a document in MongoDB collection, which field is a substring to my "string"?

只是小例子。假设我有这个集合：

Just a little example. Suppose I have this collection:

{"str": "pho", ...},
{"str": "sma", ...},
{"str": "goa", ...},
{"str": "aba", ...},
{"str": "gag", ...}
...

例如，我的字符串 是智能手机。因此查询的结果应为：

And my "string" is "smartphone" for example. So the result of the query should be:

{"str": "pho", ...}
{"str": "sma", ...}

现在我使用此正则表达式来解决我的问题：

For now I use this regex to solve my problem:

^[smartphone]+$

可以，但是也可以匹配 { str： ophms，...} 这样的文档 str不是 smartphone的子字符串。

That works, but it'll also match documents like {"str": "ophms", ...} which "str" is not a substring of "smartphone".

我知道，我的问题与＃2123738 ，但这与sql数据库有关，查询方法有所不同

I know, my question is exact like a #2123738, but that's about sql databases, which querying methods differents a lot.

推荐答案

您可以使用 $ indexOfCP 查找一个字符串是另一个的子字符串，如果是，它将返回起始索引，否则返回 -1

You can use $indexOfCP to find a string is a substring of other, if yes it will return the starting index otherwise -1

{$expr : {$gte : [{$indexOfCP: ["smartphone","$str"]},0]}}

收藏

> db.t60.find()
{ "_id" : ObjectId("5c44c5cc9d56bf65be5ab2de"), "str" : "pho" }
{ "_id" : ObjectId("5c44c5cc9d56bf65be5ab2df"), "str" : "sma" }
{ "_id" : ObjectId("5c44c5cc9d56bf65be5ab2e0"), "str" : "goa" }
{ "_id" : ObjectId("5c44c5cc9d56bf65be5ab2e1"), "str" : "aba" }

结果

> db.t60.find({$expr : {$gte : [{$indexOfCP: ["smartphone","$str"]},0]}})
{ "_id" : ObjectId("5c44c5cc9d56bf65be5ab2de"), "str" : "pho" }
{ "_id" : ObjectId("5c44c5cc9d56bf65be5ab2df"), "str" : "sma" }

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