I'm looking for a method for join a collection and a external array of strings (with codes), that returns another string array with all codes of first array that aren't included in the collection.
The collection sample:
[{
_id:ObjectId("61bf57bc9d1f93b7ae5fa785"),
"Movie": {
"Code": "123",
"OriginalTitle": "Title 1",
"Year": 2021
}},{
_id:ObjectId("61bf57bc9d1f93b7ae5fa786"),
"Movie": {
"Code": "124",
"OriginalTitle": "Title 2",
"Year": 2021
}},{
_id:ObjectId("61bf57bc9d1f93b7ae5fa787"),
"Movie": {
"Code": "125",
"OriginalTitle": "Title 3",
"Year": 2021
}},{
_id:ObjectId("61bf57bc9d1f93b7ae5fa788"),
"Movie": {
"Code": "126",
"OriginalTitle": "Title 4",
"Year": 2021
}
}]
the external array:
const codes = ["125", "127", "128", "129"];
the aggregation must compare "Movie.Code" with the array and returns another array with the next values:
returnCodes = ["127", "128", "129"];
How can I make it?
Maybe this:
db.collection.aggregate([
{
$group: {
_id: null,
Code: { $push: "$Movie.Code" }
}
},
{
$project: {
returnCodes: {
$filter: {
input: codes ,
cond: { $not: { $in: [ "$$this", "$Code" ] } }
}
}
}
}
]).toArray().shift().returnCodes
Of course, you could do it also in Javascript:
const codes = ["125", "127", "128", "129"];
const coll = db.collection.find({}, { Code: "$Movie.Code" }).toArray().map(x => x.Code);
returnCodes = codes.filter(x => !coll.includes(x));