MongoDB using skip and distinct in a query based on values inside an array - database

Question

So I have document that is structure like this
_id: ObjectId('62bbe17d8fececa06b91873d')
clubName: 'test'
staff:[
'62bbe47f8fececa06b9187d8'
'624f4b56ab4f5170570cdba3' //IDS of staff members
]
A single staff can be assigned to multiple clubs so what I'm trying to achieve is to get all staff that has been assigned to at least one club and display them on a table on the front end, I followed this solution since distinct and skip can't be used on a single query but it just returned this:
[
{ _id: [ '624f5054ab4f5170570cdd16', '624f5054ab4f5170570cdd16' ] } //staff from club 1,
{ _id: [ '624f5054ab4f5170570cdd16', '624f9194ab4f5170570cded1' ] } //staff from club 2,
{ _id: [ '624f4b56ab4f5170570cdba3' ]} //staff from club 3
]
my desired outcome would be like this:
[ _id : ['624f5054ab4f5170570cdd16', '624f9194ab4f5170570cded1', '624f4b56ab4f5170570cdba3'] ]
here's my query:
const query = this.clubModel.aggregate(
[{ $group: { _id: '$staff' } }, { $skip: 0}, { $limit: 10}],
(err, results) => {
console.log(results);
},
);
the values returned are not distinct at all, is there an operation that can evaluate the value inside an array and make them distinct?
Here's my new query after adding the 'createdAt' field in my document structure:
const query = this.clubModel.aggregate([
{ $sort: { createdAt: -1 } },
{
$unwind: '$drivers',
},
{
$project: {
isActive: true,
},
},
{
$group: {
_id: 'null',
ids: {
$addToSet: '$drivers',
},
},
},
{
$project: {
_id: 0,
},
},
{
$skip: skip,
},
{
$limit: limit,
},
]);

Answer 1

Does this works for you, first UNWIND the staff array, and then group on "_id" as null and add staff values using $addToSet:
db.collection.aggregate([
{
"$unwind": "$staff"
},
{
"$group": {
"_id": "null",
"ids": {
"$addToSet": "$staff"
}
}
},
{
"$project": {
"_id": 0,
}
},
{
$skip: 0
},
{
$limit: 10
}
])
Here's the working link.