Using $$ROOT in aggregation order
-
21-12-2019 - |
Question
I'm try get data from collection with some order:
db.data.aggregate([
{$limit: 1000},
{$group: {
_id: "$service",
count: {$sum: 1},
data: {$push: '$$ROOT'}
}}
]);
But get next error:
Error("Printing Stack Trace")@:0
()@src/mongo/shell/utils.js:37
([object Array])@src/mongo/shell/collection.js:866
@(shell):6
uncaught exception: aggregate failed: {
"errmsg" : "exception: FieldPath field names may not start with '$'.",
"code" : 16410,
"ok" : 0
}
Where did I go wrong?
Solution
So per the comment you need a MongoDB version 2.6 do do this. But of course using 2.6 this works for me:
db.collection.aggregate([
{ "$limit": 1000 },
{ "$group": {
"_id": null,
"count": { "$sum": 1},
"data": { "$push": "$$ROOT" }
}}
])
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