Mongo aggregate query group using regex

Question

I'm trying write a script and get data from collections added in year and particular month.

And also get the records where 'Name' field matches my given regex.

Is it possible to use regex group in aggregate? Something like this :

collection1.aggregate([
     {"$match": {"$expr":{"$and":[{"$eq":[{"$year":"$updated_time"}, year]}, {"$eq":[{"$month":"$updated_time"}, month]}]}}},
{$group : {_id : {"Name": {"$regex": '^ABC', "$options": "i"} },count: { $sum: 1 }}
}]

Or which is the best way to get it? how do i modify this query to get count of regex match in that time frame

Ashh · Accepted Answer · 2019-01-08 19:15:45Z

3

You can use $regex inside the $match itself and then use $count to get the number of matched document

collection1.aggregate([
  { "$match": {
    "$expr": {
      "$and": [
        { "$eq": [{ "$year": "$updated_time" }, year] },
        { "$eq": [{ "$month": "$updated_time" }, month] }
      ]
    },
    "Name": { "$regex": "^ABC", "$options": "i" }
  }},
  { "$count": "count" }
])

or either by $group as well

collection1.aggregate([
  { "$match": {
    "$expr": {
      "$and": [
        { "$eq": [{ "$year": "$updated_time" }, year] },
        { "$eq": [{ "$month": "$updated_time" }, month] }
      ]
    },
    "Name": { "$regex": "^ABC", "$options": "i" }
  }},
  { "$group": {
    "_id": null,
    "count": { "$sum": 1 }
  }}
])

edited Jan 8, 2019 at 19:15

answered Jan 8, 2019 at 15:53

Ashh

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6 Comments

Rachel Over a year ago

Thank you that works !! Had another query im trying to output the data to another collection by grouping as below : { "$group": {"_id": null,"count": { "$sum": 1 }},"updated_time":{ "$push": "$updated_time" }}, { "$out" : "new_Coll" }.. But this is adding updates times as per count value. I want update_time only once in new collection

Ashh Over a year ago

It will add count and the update_time array nothing else

Rachel Over a year ago

Yeah update_time is added multiple times if the count is 5 updated_time is added 5 times. Is my push statement incorrect ?

Ashh Over a year ago

Yes it will add 5 time as the number of documents are also 5.

Rachel Over a year ago

is it possible to add only once ?

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