Menu
I'm try get data from collection with some order:
db.data.aggregate([
{$limit: 1000},
{$group: {
_id: "$service",
count: {$sum: 1},
data: {$push: '$$ROOT'}
}}
]);
But get next error:
Error("Printing Stack Trace")@:0
()@src/mongo/shell/utils.js:37
([object Array])@src/mongo/shell/collection.js:866
@(shell):6
uncaught exception: aggregate failed: {
"errmsg" : "exception: FieldPath field names may not start with '$'.",
"code" : 16410,
"ok" : 0
}
Where did I go wrong?
542
$replaceRoot. Replaces the input document with the specified document. The operation replaces all existing fields in the input document, including the _id field. You can promote an existing embedded document to the top level, or create a new document for promotion (see example).
In MongoDb, the aggregation is assisted by several methods and operators that can perform different tasks. Among those operators, the $sort operator helps to sort the documents and return the documents in an organized order. And for group sorting in MongoDB, the $group operator is used with the $sort operator.
Definition. Evaluates a boolean and returns the opposite boolean value; i.e. when passed an expression that evaluates to true , $not returns false ; when passed an expression that evaluates to false , $not returns true . For more information on expressions, see Expressions.
So per the comment you need a MongoDB version 2.6 do do this. But of course using 2.6 this works for me:
db.collection.aggregate([
{ "$limit": 1000 },
{ "$group": {
"_id": null,
"count": { "$sum": 1},
"data": { "$push": "$$ROOT" }
}}
])
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
