How to split string in MongoDB?

Question

The example data is as following:

{"BrandId":"a","Method":"PUT","Url":"/random/widgets/random/state"}
{"BrandId":"a","Method":"POST","Url":"/random/collection/random/state"}
{"BrandId":"b","Method":"PUT","Url":"/random/widgets/random/state"}
{"BrandId":"b","Method":"PUT","Url":"/random/widgets/random/state"}

I need to find all the rows with method=put and Url in a pattern /random/widgets/random/state. "random" is a random string with a fixed length. the expected result is :

{"BrandId":"a","total":1}
{"BrandId":"b","total":2}

I tried to write so code as :

db.accessLog.aggregate([
    {$group: {
        _id: '$BrandId',
        total: {
                $sum:{
                  $cond:[{$and: [ {$eq: ['$Method', 'POST']},
                        {Url:{$regex: /.*\/widgets.*\/state$/}} ]}, 1, 0]
                }
            },
    {$group: {
        _id: '$_id',
       total:{$sum:'$total'}
    }
])

but the regular expression does not work, so I suppose I need to try other way to do it, perhaps split string. And I need to use $cond. please keep it. Thanks!

score 1 · Answer 1 · answered May 14 '15 at 00:34

1

You can use the following query to achieve what you want, I assume the data in a collection named 'products'

db.products.aggregate([
                {$match : {'Method':'PUT','Url':/.*widgets.*\/state$/ }},
                {$group: {'_id':'$BrandId','total':{$sum: 1} }}
        ]);

1. $match: Find all documents that has 'PUT' method and Url in the specified pattern.

2. $group: Group by brand Id and for each entry, count 1

answered May 14 '15 at 00:34

Toan Nguyen

11,263
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Sorry, I need to put the code under $cond as I mentioned. Please let me know if it is possible. – erkpwejropi May 14 '15 at 00:44
Instead of {$regex: /.*\/widgets.*\/state$/}, use /.*widgets.*\/state$/ – Toan Nguyen May 14 '15 at 00:47
I have complicated code, and I need a solution can be used under $cond. and regular expression can not work, that is why I ask this question. – erkpwejropi May 14 '15 at 00:56
1

You can use my code to achieve what you want, it is far more simpler. Other than that, I cannot help – Toan Nguyen May 14 '15 at 01:02
sorry, you code is something I already know. I need to put it under $cond, so I ask this question. – erkpwejropi May 14 '15 at 01:15

score 0 · Answer 2 · edited May 23 '17 at 12:30

0

Greedy matching is the problem.

Assuming non-zero number of 'random' characters (sounds sensible), try a regex of:

/[^\/]+\/widgets\/[^\/]+\/state$/

edited May 23 '17 at 12:30

Community

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1

answered May 13 '15 at 22:49

declension

4,110
22
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Sorry, I suppose regular expression does not work in $cond. as I mentioned that I need another way to do it. – erkpwejropi May 13 '15 at 23:36
Looks like [you can't do that](http://docs.mongodb.org/manual/reference/operator/aggregation/group/#accumulator-operator). Perhaps you should just filter your collection before aggregating, i.e. use a `$match` with `$regex` ([which *is* supported](http://docs.mongodb.org/manual/reference/operator/query/#query-selectors)). – declension May 14 '15 at 08:42

How to split string in MongoDB?

2 Answers2