在MongoDB中，如何根据一个字符串字段是否包含另一个字符串字段来执行查询 [英] In MongoDB, how to perform query based on if one string field contains another

问题描述

您好，请帮助我. 在mongodb中，我有一个这样的集合:

Hello please help me with this. In mongodb, I have a collection like this:

data1= {
    "string1":"abc",
    "string2":"abcde"
}

data2= {
    "string1":"abc",
    "string2":"ftgr"
}

查询后，我只想返回data1，因为它的string2属性包含其string1属性的内容.我该如何进行这项工作?我应该使用$ where还是使用正则表达式?如果有人可以给小费，我将非常感激.

After the query I only want to return data1 because it's string2 property contains the contents of it's string1 property. How can I make this work? Should I use $where or using regex? Very very appreciated if someone can point a tip.

推荐答案

您可以通过为string1创建一个RegExp然后针对string2对其进行测试，来对$where进行此操作:

You can do this with $where by creating a RegExp for string1 and then testing it against string2:

db.test.find({$where: 'RegExp(this.string1).test(this.string2)'})

但是，如果您使用的是MongoDB 3.4+，则可以使用

However, if you're using MongoDB 3.4+ you can do this more efficiently by using the $indexOfCP aggregation operator:

db.test.aggregate([
    // Project  the index of where string1 appears in string2, along with the original doc.
    {$project: {foundIndex: {$indexOfCP: ['$string2', '$string1']}, doc: '$$ROOT'}},
    // Filter out the docs where the string wasn't found
    {$match: {foundIndex: {$ne: -1}}},
    // Promote the original doc back to the root
    {$replaceRoot: {newRoot: '$doc'}}
])

或更直接使用$redact:

db.test.aggregate([
    {$redact: {
        $cond: {
            if: { $eq: [{$indexOfCP: ['$string2', '$string1']}, -1]},
            then: '$$PRUNE',
            else: '$$KEEP'
        }
    }}
])

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