how to count number of keys in embedded mongodb document - sql

Question

I have a mongodb query: (Give me the settings where account='test')
db.collection_name.find({"account" : "test1"}, {settings : 1}).pretty();
where I get the following sample output:
{
"_id" : ObjectId("49830ede4bz08bc0b495f123"),
"settings" : {
"clusterData" : {
"us-south-1" : "cluster1",
"us-east-1" : "cluster2"
},
},
What I'm looking for now, is to give me the account where the clusterData has more than 1 key.
I'm only interested in listing those accounts with (2) or more keys.
I've tried this: (but this doesn't work)
db.collection_name.find({'settings.clusterData.1': {$exists: true}}, {account : 1}).pretty();
Is this possible to do with the current data structure? I don't have the option to redesign this schema.

Answer 1

Your clusterData field is not an array which is why you cannot just filter the number of elements it has. There is a way, though, to get what you want via the aggregation framework. Try this:
db.collection_name.aggregate({
$match: {
"account" : "test1"
}
}, {
$project: {
"settingsAsArraySize": { $size: { $objectToArray: "$settings.clusterData" } },
"settings.clusterData": 1
}
}, {
$match: {
"settingsAsArraySize": { $gt: 1 }
}
}, {
$project: {
"_id": 0,
"settings.clusterData": 1
}
}).pretty();