/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

13 votes190 views6 answers
React native typescript
TypeScript
4 votes189 views2 answers
When manual testing
TypeScript
0 vote208 views1 answer
@Jaredmiro12
TypeScript
1 vote197 views1 answer
How to send data between components in react with redirect
TypeScript
1 vote201 views1 answer
Typescript assigning parameter is forbidden
TypeScript
7 votes254 views3 answers
Class 'kotlin.Unit' was compiled with an incompatible version of Kotlin. The binary version of its metadata is 1.5.1, expected version is 1.1.15.
TypeScript
0 vote201 views2 answers
List elements not in indices
TypeScript
3 votes183 views1 answer
Empty observable rxjs
TypeScript
1 vote237 views2 answers
How to get all elements of column in pandas dataframe
TypeScript
0 vote209 views1 answer
Nullish Coalescing
TypeScript