node.js 如何在 $match 内的 mongodb 聚合查询中使用 $regex
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How to use $regex in mongodb aggregation query within $match
提问by Amol M Kulkarni
I am trying to use the $regexwithin $match, its not returning the matching documents.
我正在尝试使用$regexinside $match，它不返回匹配的文档。
db.collection('MyCollection', function (err, collection) {
collection.aggregate([
{ $match: { 'Code': 'Value_01', 'Field2': { $regex: '/Value_2/g' } } },
{ $project: {
_id: 1,
CodeNumber: '$Code',
FieldName2: '$Field2'
}
}
], function (err, Result_doc) {
console.log(Result_doc);
}
});
Can anyone tell me where its going wrong or the correct syntax?
谁能告诉我哪里出了问题或正确的语法？
我什至尝试更换
'Field2': { $regex: /Value_2/g }
回答by JohnnyHK
As it says in the $regexdocs you linked to, the two ways to do this are:
正如$regex您链接到的文档中所说，执行此操作的两种方法是：
Field2: /Value_2/g
OR
或者
Field2: { $regex: 'Value_2', $options: 'g' }
But I also tried your second attempt of 'Field2': { $regex: /Value_2/g }and that worked as well.
但我也尝试了你的第二次尝试，结果'Field2': { $regex: /Value_2/g }也很好。
BTW, the gregex option doesn't make sense in this context as you just need one match anyway. Note that it isn't even listed in the $regexdocs.
顺便说一句，g正则表达式选项在这种情况下没有意义，因为无论如何您只需要一个匹配项。请注意，它甚至没有在$regex文档中列出。
回答by Amol M Kulkarni
I got it working with the following code:
我用下面的代码让它工作：
var Value_match = new RegExp('Value_2');
db.collection('MyCollection', function (err, collection) {
collection.aggregate([
{ $match: { Code: 'Value_01', Field2: { $regex: Value_match } } },
{ $project: {
_id: 1,
CodeNumber: '$Code',
FieldName2: '$Field2'
}
}
], function (err, Result_doc) {
console.log(Result_doc);
}
});
On pushing the object content to console using console.dir(Value_match)it prints out '/Value_2/'
使用console.dir(Value_match)它将对象内容推送到控制台时会打印出来'/Value_2/'
