mongodb - left join with conditions - node.js

Question

I am attempting an left antijoin on these two collections.
I want all users where department is equal to 'IT' that aren't in a meeting that had an endAt time > 175. Either as a creator or receiver.
So essentially whoever hasn't been in a meeting in the last xxx time.
Based on below collections:
John would be retrieved because he is apart of department IT and has not been a receiver or creator after '175'.
Jane has an endAt time after 175 and is in IT so wouldn't be retrieved
Bill is apart of finance so even though he hasn't been it doesn't matter
Bob has an endAt time after 175 and is in IT so wouldn't be retrieved
Mary is in IT and has not been in any meetings so she is retrieved.
Users Collection:
[
{
_id: ObjectId("1"),
name: "john",
department: 'IT'
},
{
_id: ObjectId("2"),
name: "jane",
department: 'IT'
},
{
_id: ObjectId("3"),
name: "bill",
department: 'finance'
},
{
_id: ObjectId("4"),
name: "Bob",
department: 'IT'
},
{
_id: ObjectId("5"),
name: "Mary",
department: 'IT'
}
]
Meetings Collection:
[
{
_id: ObjectId("a"),
endedAt: 100,
creator_id: ObjectId("1"),
receiver_id: ObjectId("2")
},
{
_id: ObjectId("b"),
endedAt: 150,
creator_id: ObjectId("1"),
receiver_id: ObjectId("3")
},
{
_id: ObjectId("c"),
endedAt: 200,
creator_id: ObjectId("4"),
receiver_id: ObjectId("2")
},
{
_id: ObjectId("d"),
endedAt: 250,
creator_id: ObjectId("2"),
receiver_id:
}
]
Output:
[
{
_id: ObjectId("1"),
name: "john",
department: 'IT'
},
{
_id: ObjectId("5"),
name: "Mary",
department: 'IT'
}
]
My approach:
db.users.aggregate([
{
$match:
{
type: 'IT'
}
},
{
$lookup:
{
from: "meetings",
let:
{
userid: "$_id",
},
pipeline: [
{ $match:
{ $expr:
{
$and:[
{
$or: [
{ $eq: ["$receiver_id", "$$userid"] },
{ $eq: ["$creator_id", "$$userid"] },
]
},
{ $gt: ["$endAt", 175] }
]
}
}
}
],
as: "result"
}
},
{
$unwind:
{
path: "$result",
preserveNullAndEmptyArrays: true
}
},
{
$match:
{
result: {$exists:false}
}
}
])

Answer 1

Query
match "IT"
join if >175 AND (userid in any of the 2 (creator/receiver))
*its lookup pipeline, because multiple join creteria
reject those that are joined
Test code here
db.users.aggregate([
{
"$match": {
"department": {
"$eq": "IT"
}
}
},
{
"$lookup": {
"from": "meetings",
"let": {
"userid": "$_id"
},
"pipeline": [
{
"$match": {
"$expr": {
"$and": [
{
"$gt": [
"$endedAt",
175
]
},
{
"$or": [
{
"$eq": [
"$$userid",
"$creator_id"
]
},
{
"$eq": [
"$$userid",
"$receiver_id"
]
}
]
}
]
}
}
},
{
"$project": {
"_id": 1
}
}
],
"as": "meetings"
}
},
{
"$match": {
"$expr": {
"$eq": [
"$meetings",
[]
]
}
}
},
{
"$unset": [
"meetings"
]
}
])

Answer 2

aggregate
db.users.aggregate([
{
"$match": {
department: "IT"
}
},
{
"$lookup": {
"from": "meeting",
"localField": "_id",
"foreignField": "creator_id",
"as": "meeting_creator"
}
},
{
"$lookup": {
"from": "meeting",
"localField": "_id",
"foreignField": "receiver_id",
"as": "meeting_receiver"
}
},
{
"$match": {
"$and": [
{
"meeting_creator.endedAt": {
"$not": {
"$gt": 175
}
}
},
{
"meeting_receiver.endedAt": {
"$not": {
"$gt": 175
}
}
}
]
}
},
{
"$project": {
_id: 1,
name: 1,
department: 1
}
}
])
data
db={
"users": [
{
_id: "1",
name: "john",
department: "IT"
},
{
_id: "2",
name: "jane",
department: "IT"
},
{
_id: "3",
name: "bill",
department: "finance"
},
{
_id: "4",
name: "Bob",
department: "IT"
},
{
_id: "5",
name: "Mary",
department: "IT"
}
],
"meeting": [
{
_id: "a",
endedAt: 100,
creator_id: "1",
receiver_id: "2"
},
{
_id: "b",
endedAt: 150,
creator_id: "1",
receiver_id: "3"
},
{
_id: "c",
endedAt: 200,
creator_id: "4",
receiver_id: "2"
},
{
_id: "d",
endedAt: 250,
creator_id: "2",
receiver_id: ""
}
]
}
result
[
{
"_id": "1",
"department": "IT",
"name": "john"
},
{
"_id": "5",
"department": "IT",
"name": "Mary"
}
]
mongoplayground

Answer 3

This is the solution I came up with that ended up working, does anyone have any details what would be the most efficient?
db.users.aggregate([
{
$match:
{
type: 'IT'
}
},
{
$lookup:
{
from: "meetings",
let:
{
userid: "$_id",
},
pipeline: [
{ $match:
{ $expr:
{
$and:[
{
$or: [
{ $eq: ["$receiver_id", "$$userid"] },
{ $eq: ["$creator_id", "$$userid"] },
]
},
{ $gt: ["$endAt", 175] }
]
}
}
}
],
as: "result"
}
},
{
$unwind:
{
path: "$result",
preserveNullAndEmptyArrays: true
}
},
{
$match:
{
result: {$exists:false}
}
}
])