Finding all docs that match minimum amount of array values - mongodb

Question

First time I am writing MongoDB query and managed up to certain point for now but stuck at the moment. I looked into the match property but not sure if it is relevant.
The query below will return all the user documents that contain at least one given role.
roles := []string{"admin", "super_admin", "manager", "student"}
a.db.Collection("users").Find(ctx, bson.M{"roles": bson.M{"$in": roles}})
// db.users.find({roles: { $in: ["admin", "super_admin", "manager", "student"] }})
What I need now is that, specify the minimum matching criteria. For example, the user document must match at least 2 given roles (doesn't matter which ones they are). I will need to use something like EQ, GTE, GT, LT, LTE operators.
Update
It is ok to just handle minimum match so happy to ignore all the listed operators above.

Answer 1

I am not sure there are any other easy way to achieve this, you can use aggregation operators in find if you are using MongoDB v4.4 or you can use aggregate(), I don't know about go syntax but I can do it in MongoDB driver query,
$reduce to iterate loop of roles array, se initial value to 0, check condition if current role is in you input role then add one in initial value otherwise return existing initial value,
check expression with $gte that return number is greater than 2
db.users.find({
$expr: {
$gte: [
{
$reduce: {
input: "$roles",
initialValue: 0,
in: {
$cond: [
{ $in: [$$this", ["admin","super_admin","manager","student"]] },
{ $add: ["$$value", 1] },
"$$value"
]
}
}
},
2 // input your number
]
}
})
Playground
Using aggregate():
Playground

Answer 2

Follows up to accepted answer, this is the Go version of it. Just for those who might need some reference.
filter := bson.M{
"$expr": bson.M{
"$gte": []interface{}{
bson.M{
"$reduce": bson.M{
"input": "$roles",
"initialValue": 0,
"in": bson.M{
"$cond": []interface{}{
bson.M{
"$in": []interface{}{
"$$this",
roles, // This is your []string slice
},
},
bson.M{
"$add": []interface{}{
"$$value",
1,
},
},
"$$value",
},
},
},
},
minMatch, // This is the limit
},
},
}