Searching value in 2 different fields mongodb + node.js - node.js

Question

I am newbie. But I try to learn the most logical ways to write the queries.
Assume I have collection which is as;
{
"id" : NumberInt(1),
"school" : [
{
"name" : "george",
"code" : "01"
},
{
"name" : "michelangelo",
"code" : "01"
}
],
"enrolledStudents" : [
{
"userName" : "elisabeth",
"code" : NumberInt(21)
}
]
}
{
"id" : NumberInt(2),
"school" : [
{
"name" : "leonarda da vinci",
"code" : "01"
}
],
"enrolledStudents" : [
{
"userName" : "michelangelo",
"code" : NumberInt(25)
}
]
}
I want to list occurence of a key with their corresponding code values.
As an example key : michelangelo
To find the occurence of the key, I wrote two differen aggregation queries as;
db.test.aggregate([
{$unwind: "$school"},
{$match : {"school.name" : "michelangelo"}},
{$project: {_id: "$id", "key" : "$school.name", "code" : "$school.code"}}
])
and
db.test.aggregate([
{$unwind: "$enrolledStudents"},
{$match : {"enrolledStudents.userName" : "michelangelo"}},
{$project: {_id: "$id", "key" : "$enrolledStudents.userName", "code" : "$enrolledStudents.code"}}
])
the result of these 2 queries return what I want as;
{ "_id" : 1, "key" : "michelangelo", "code" : "01" }
{ "_id" : 2, "key" : "michelangelo", "code" : 25 }
One of them to search in enrolledStudents, the other one is searching in school field.
Can these 2 queries reduced into more logical query? Or is this the only way to do it?
ps: I am aware that database structure is not logical, but I tried to simulate.
edit
I try to write a query with find.
db.test.find({$or: [{"enrolledStudents.userName" : "michelangelo"} , {"school.name" : "michelangelo"}]}).pretty()
but this returns the whole documents as;
{
"id" : 1,
"school" : [
{
"name" : "george",
"code" : "01"
},
{
"name" : "michelangelo",
"code" : "01"
}
],
"enrolledStudents" : [
{
"userName" : "elisabeth",
"code" : 21
}
]
}
{
"id" : 2,
"school" : [
{
"name" : "leonarda da vinci",
"code" : "01"
}
],
"enrolledStudents" : [
{
"userName" : "michelangelo",
"code" : 25
}
]
}

Answer 1

Mongo 3.4
$match - This stage will keep all the school array and enrolledStudents where there is atleast one embedded document matching both the query condition
$group - This stage will combine all the school and enrolledStudents array to 2d array for each _id in a group.
$project - This stage will $filter the merge array for matching query condition and $map the array to with new labels values array.
$unwind - This stage will flatten the array.
$addFields & $replaceRoot - This stages will add the id field and promote the values array to the top.
db.collection.aggregate([
{$match : {$or: [{"enrolledStudents.userName" : "michelangelo"} , {"school.name" : "michelangelo"}]}},
{$group: {_id: "$id", merge : {$push:{$setUnion:["$school", "$enrolledStudents"]}}}},
{$project: {
values: {
$map:
{
input: {
$filter: {
input: {"$arrayElemAt":["$merge",0]},
as: "onef",
cond: {
$or: [{
$eq: ["$$onef.userName", "michelangelo"]
}, {
$eq: ["$$onef.name", "michelangelo"]
}]
}
}
},
as: "onem",
in: {
key : { $ifNull: [ "$$onem.userName", "$$onem.name" ] },
code : "$$onem.code"}
}
}
}
},
{$unwind: "$values"},
{$addFields:{"values.id":"$_id"}},
{$replaceRoot: { newRoot:"$values"}}
])
Sample Response
{ "_id" : 2, "key" : "michelangelo", "code" : 25 }
{ "_id" : 1, "key" : "michelangelo", "code" : "01" }
Mongo <= 3.2
Replace last two stages of above aggregation with $project to format the response.
{$project: {"_id": 0 , id:"$_id", key:"$values.key", code:"$values.code"}}
Sample Response
{ "_id" : 2, "key" : "michelangelo", "code" : 25 }
{ "_id" : 1, "key" : "michelangelo", "code" : "01" }
You can use $redact instead of $group & match and add $project with $map to format the response.
$redact to go through a document level at a time and perform $$DESCEND and $$PRUNE on the matching criteria.
The only thing to note is usage of $ifNull in the first document level for id so that you can $$DESCEND to embedded document level for further processing.
db.collection.aggregate([
{
$redact: {
$cond: [{
$or: [{
$eq: ["$userName", "michelangelo"]
}, {
$eq: ["$name", "michelangelo"]
}, {
$ifNull: ["$id", false]
}]
}, "$$DESCEND", "$$PRUNE"]
}
},
{
$project: {
id:1,
values: {
$map:
{
input: {$setUnion:["$school", "$enrolledStudents"]},
as: "onem",
in: {
key : { $ifNull: [ "$$onem.userName", "$$onem.name" ] },
code : "$$onem.code"}
}
}
}
},
{$unwind: "$values"},
{$project: {_id:0,id:"$id", key:"$values.key", code:"$values.code"}}
])