MongoDB: How to count number of values in key

use $size to get records with 2 number of type

The $size operator matches any array with the number of elements specified by the argument. For example:

db.collection.find({  type: { "$size": 2 } // match document with type having size 2},  { name: 1 } // projection to get name and _id only  )

arrays json mongodb

To get the length of the array you should use $size operator in $project pipeline stage

So the pipeline $project stage should look like this

{  "$project": {    "name": "$name",    type: {      "$size": "$type"    }  }}

Here is an working example of the same ⇒ https://mongoplayground.net/p/BmS9BGhqsFg

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