Template
single collection
multiple collections
mgodatagen
update
indexe
explain
Stage
Database
bson
mgodatagen
[{"name":1,"array":[1,2,3]},{"name":2,"array":[]}]
Query
db.collection.aggregate([{$addFields:{date:{$cond:[{$gt:[{$size:"$array"},0]},"$$NOW","$$REMOVE"]}}}])
Result