Check if subdocument in range complies with a condition - mongodb

Question

I'm working on a mongoDB query.
I have several documents which I query with following results:
{
"_id" : 1000.0,
"date" : ISODate("2018-05-25T00:20:00.000Z"),
"value" : true
}
{
"_id" : 1000.0,
"date" : ISODate("2018-05-25T00:26:00.000Z"),
"value" : false
}
{
"_id" : 1000.0,
"date" : ISODate("2018-05-25T00:30:00.000Z"),
"value" : false
}
The original documents are filtered so that I get only document within the last 15 minutes before now and there is no way of knowing how many entries are in that time range.
I need to expand my existing query so that it returns a status based on the "value". If there are no true I need a status 0, if there is at least 1 but not only true I need a status 1, and if there are only true I need a status 2.
For example:
{
"_id" : 1000,
"status" : 1
},
{
"_id" : 1001,
"status" : 2
}
Is there a way of accomplishing this using mongoDB? Or would it be better/easier to do it on java side? Note that there are several _id in the database.

Answer 1

You can gather all values from each group into one array (using $group and $push) and then use $switch to apply your logic. To determine whether array contains any true value or all values are true you can use $anyElementTrue and $allElementsTrue:
db.col.aggregate([
{
$group: {
_id: "$_id",
values: { $push: "$value" }
}
},
{$unwind:"$values"},
{
$project: {
_id: 1,
status: {
$switch: {
branches: [
{ case: { $allElementsTrue: "$values" }, then: 2 },
{ case: { $anyElementTrue: "$values" }, then: 1 },
],
default: 0
}
}
}
}
])