I have a document with an array field that contains a list of values and I would like to sort by the first element in the array.
{
field1 : "bla",
field2 : "bla",
field3 : "bla",
someArray : [123, 456, 789]
}
I was trying to query like this:
db.testCollection.find({}).sort({"someArray[0]" : 1})
But this does not seem to have any effect and the sort gets ignored.
Is there any way this can be done?
Yes, the way to sort your collection by the first element of someArray in increasing order is:
db.testCollection.find().sort({"someArray.0": 1})
There is no need for the aggregation framework here. You were very close!
It is not ignoring the ascending sort, but it sorts according to min value in the each array.
This thing not possible in directly mongo find query so you should use mongo aggregation as below
db.collectionName.aggregate({"$unwind":"$someArray"},{"$sort":{"someArray":-1}})
but above aggregation takes too much recurssion as it caused performance issue. So I think it should poosible to update someArray in sorting order and then used findquery so it shows results in someArray in sorted manner. Below query update someArray
db.collectionName.update({},{"$push":{"someArray":{"$each":[],"$sort":-1}}},false,true)
last true used for updating multiple documents. When update complete then simple find query as db.collectionName.find().pretty()
