/TypeScript/Mongodb count based on array of ids

Mongodb count based on array of ids

Mongo count elements in array

> db.mycollection.insert({'foo':[1,2,3,4]})
> db.mycollection.insert({'foo':[5,6,7]})

> db.mycollection.aggregate([{$project: { count: { $size:"$foo" }}}])
{ "_id" : ObjectId("5314b5c360477752b449eedf"), "count" : 4 }
{ "_id" : ObjectId("5314b5c860477752b449eee0"), "count" : 3 }

Source: stackoverflow.com

Mongo count elements in array

{ $size: <expression> }

Source: docs.mongodb.com

Mongodb count based on array of ids

db.collection.aggregate([
    { $unwind: "$connects" },

    // count all occurrences
    { "$group": { "_id": {skill: "$skill", parser_id: "$connects.parser_id"}, "count": { "$sum": 1 } }},

    // sum all occurrences and count distinct
    { "$group": { "_id": "$_id.skill", "quantity": { "$sum": 1 } }},

    // (optional) rename the '_id' attribute to 'skill'
    { $project: { 'skill': '$_id', 'quantity': 1, _id: 0 } }
])

Source: stackoverflow.com

Similar codes

0 vote177 views1 answer
Angular Workspace
TypeScript
0 vote164 views1 answer
Make foreign key sql in exists row
TypeScript
3 votes183 views1 answer
/C:/flutter/packages/flutter/lib/src/widgets/localizations.dart:413:17: Context: Found this candidate, but the arguments don't match.
TypeScript
1 vote219 views1 answer
Main concepts in asp.net core
TypeScript
1 vote211 views1 answer
Conditional (click) action angular
TypeScript
0 vote171 views2 answers
Python remove all double elements from list
TypeScript
5 votes176 views2 answers
How to create empty object typescript
TypeScript
0 vote173 views1 answer
How to make game objects spread in a specific vector
TypeScript
0 vote206 views1 answer
How to add 2 bind events on one button tkinteer
TypeScript
19 votes209 views4 answers
Number of digits in a number python
TypeScript