Mongoose findOne to return count of object's sub-array [duplicate]

Question

I have data like this:

{
  "profileID": "123456789",
  "myArray": [
    {
      "read": false
    },
    {
      "read": true
    },
    {
      "read": false
    },
    {
      "read": true
    }
  ]
}

I want to be able to get the count of: myArray where read is false. I need to do this on Mongoose. In the example above, the return I want is 2.

My findOne is like below:

userModel.findOne({'profileID': 123456789}, function(err, myArray) {
    //Code to run here
});

I can manually run through the response and make my count that way but that will be very ineffeciant.

How do I get the count of the user's myArray's unread values on the database level?

Thanks

Robert Seaman · Accepted Answer · 2017-04-16 09:10:20Z

2

You should use aggregate:

> db.bla.insert({
...   "profileID": "123456789",
...   "myArray": [
...     {
...       "read": false
...     },
...     {
...       "read": true
...     },
...     {
...       "read": false
...     },
...     {
...       "read": true
...     }
...   ]
... })
WriteResult({ "nInserted" : 1 })

> db.bla.aggregate([{$match:{"profileID":"123456789"}}, {$unwind:"$myArray"}, {$match:{"myArray.read":false}}, {$count:"unread_mail"}])
{ "unread_mail" : 2 }

You can then $unwind your array to do your count.

answered Apr 16, 2017 at 9:10

Robert Seaman

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1 Comment

Sean Over a year ago

Works like a charm mate! Initially I had an issue with $count but then I looked up the documentation for Mongo that it was introduced in version 3.4 and I was on version 3.2.x So all good after the upgrade. Thanks!

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