Mongo: filter documents from multiple collections and merge - node.js

Question

I am new to mongo and NodeJS and have a use case where I want to get filtered results from multiple collection.
Advance apologies for the long post.
for ex:
collectionA
{
"_id" : "foo#gmail.com",
"name" : "Foo",
"location" : {
"coordinates" : [
-122.420170,
37.780080
],
"type" : "Point"
}
},
{
"_id" : "bar#gmail.com,
"name" : "Bar",
"location" : {
"coordinates" : [
-122.420060,
37.780180
],
"type" : "Point"
}
}
collectionB: Some attributes are not present for all the documents and hence optional
{
"_id" : "foo#gmail.com"
"AttributeA" : [
{
"name" : "AttA_Name",
"val" : "Coll_B_AttA_Val_Foo"
},
{
"name" : "AttA_Name1",
"val" : "Coll_B_AttA_Val_Foo"
}]
},
{
"_id" : "bar#gmail.com"
"AttributeA" : [
{
"name" : "AttA_Name",
"val" : "Coll_B_AttA_Val_Bar"
},
{
"name" : "AttA_Name2",
"val" : "Coll_B_AttA_Val_Bar"
}
],
"AttributeB" : [
{
"name" : "AttB_Name",
"val" : "Coll_B_AttB_Val_Bar"
}
]
}
CollectionC: Some attributes are not present for all the documents and hence optional
{
"_id" : "foo#gmail.com"
"AttributeA" : [
{
"name" : "Coll_C_AttA_Name",
"val" : "Coll_C_AttA_Val_Foo"
}]
},
{
"_id" : "bar#gmail.com"
"AttributeA" : [
{
"name" : "Coll_C_AttA_Name",
"val" : "Coll_C_AttA_Val_Bar"
}
],
"AttributeB" : [
{
"name" : "Coll_C_AttB_Name",
"val" : "Coll_C_AttB_Val_Bar"
}
]
}
I know Collection B and C schema looks the same but the purpose is different and they have to be different. DB design is not the question so I would appreciate if do not put all the focus on it.
Query:
Assume there is another user (Alan) with same attributes present as Bar that exist in the collection but is not living nearby the location of Bar.
The query I am trying to build on top of these is,
Find people living nearby from CollectionA
And Collection B, if AttributeA exist and have an element with name: AttA_Name
And in Collection C, if AttributeA exist and have an name: Coll_C_AttA_Name
In the above case I am expecting a result as
{
"_id" : "foo#gmail.com",
"name" : "Foo",
"location" : {
"coordinates" : [
-122.420170,
37.780080
],
"type" : "Point"
},
"collectionB_AttributeA" : [
{
"name" : "AttA_Name",
"val" : "Coll_B_AttA_Val_Foo"
},
{
"name" : "AttA_Name1",
"val" : "Coll_B_AttA_Val_Foo"
}]
,
"collectionC_AttributeA" : [
{
"name" : "Coll_C_AttA_Name",
"val" : "Coll_C_AttA_Val_Foo"
}]
},
{
"_id" : "bar#gmail.com,
"name" : "Bar",
"location" : {
"coordinates" : [
-122.420060,
37.780180
],
"type" : "Point"
},
"collectionB_AttributeA":[
{
"name" : "AttA_Name",
"val" : "Coll_B_AttA_Val_Bar"
},
{
"name" : "AttA_Name2",
"val" : "Coll_B_AttA_Val_Bar"
}
],
"collectionC_AttributeA":[
{
"name" : "Coll_C_AttA_Name",
"val" : "Coll_C_AttA_Val_Bar"
}
]
}
There is one way of doing is in parts:
query Collection A and get the nearby people
Loop through the result of 1 and find in CollectionB if they have AttributeA and an element with name AttA_Name and eliminate if they don't match.
Loop through the filtered results from 2 and find in CollectionC if they have AttributeA and and element with name Coll_C_AttA_Name and if they don't eliminate such documents.
Is there a way I can use aggregate to build this query as one? I tried reading and trying the aggregate but seems like my understanding is incomplete.
let result = await CollectionASchema.aggregate([
{
$geoNear: {
near: { type: "Point", coordinates: [ Number(long) , Number(lat) ] },
distanceField: "dist.calculated",
minDistance: 0,
maxDistance: radiusinmetres,
spherical: true
}
},
{
$lookup:
{
from: 'collectionB',
pipeline: [
{ $match : { $and: [{ AttributeA :{$exists: true}}, { [category]: { $elemMatch: { name: “AttA_Name” } } }] }},
{ $project: { AttributeA: 0 } }
],
as: "collectionB_AttributeA"
}
}
])
If you can explain if this is possible or let me know off this is the right approach that would be helpful.