how to select value if key is uuid in mongodb - mongodb-query

Question

the mongodb data like this:
{
"_id": "123dsadasfa454sdsaw",
"hashmap": {
"uuid-12sadsadw5": {
"name": "bob"
},
"uuid-12sadsadwew5": {
"name": "alice"
}
},
"age": 10
}
"hashmap" like java HashMap, the key is uuid like "uuid-12sadsadwew5" and the value is object.
I want to get the data which the name in "hashmap" value is not null. And I use sql :
db.tabl1.find({"hashmap.values.name":{$ne:null}})
but cannot get the right result

Answer 1

You can use this aggregation query:
First use $objectToArray to create an array with values k and v. As we don't know the key (k) we can search by value (v).
Then $unwind array
And $match values where name is not null.
And then regroup and recreate the object using $arrayToObject.
db.collection.aggregate([
{
"$set": {
"hashmap": {
"$objectToArray": "$hashmap"
}
}
},
{
"$unwind": "$hashmap"
},
{
"$match": {
"hashmap.v.name": {
"$ne": null
}
}
},
{
"$group": {
"_id": "$_id",
"hashmap": {
"$push": "$hashmap"
}
}
},
{
"$set": {
"hashmap": {
"$arrayToObject": "$hashmap"
}
}
}
])
Example here