Max and min in mongodb

Question

I have the a collection of entries as follows:

{
  company:"C3",
  model:"M3",
  price:55600,
  discount:9,
  ...
}

and there are more than 2000 entries.

I am trying to find out max and min prices in the whole collection.

Maybe with something along the lines of:

db.collection.find({ max: { $max: "$price" }, min: { $min: "$price" } });

I'd like the output as { max: 2000, min: 5000 }.

Answer 1

You need to use the .aggregate() method for it to work.

db.collection.aggregate([ 
    { "$group": { 
        "_id": null,
        "max": { "$max": "$price" }, 
        "min": { "$min": "$price" } 
    }}
])

The _id field is mandatory in the $group stage and to find the max/min values for price for the hole collection not for special group it needs to be set to null otherwise the query will only return max/min for each group