How to get minimum value in pyMongo

I have a collection with several fields, and I'd like to get the minimum value from one. I know a command for getting the max value:

collection.find_one(sort=[("myfield", -1)])["myfield"]

but not one for getting the min. Is there a way to do this?

You can reverse the sort direction to get the minimum instead of the maximum value:

# Sort by myfield (ascending value) and return first document
 collection.find_one(sort=[("myfield", 1)])["myfield"]

This example assumes that:

• myfield is a numeric value (so the sort order makes sense to determine a minimum or maximum)

• myfield exists in the matching document returned (otherwise Python will report a KeyError when trying to reference a non-existent field).

• all documents in the collection have a myfield value (documents that have do not have a myfield value will sorted before the minimum numeric values)

To ensure your sort is based on documents that actually have a myfield value you can add $exists to the query criteria:

collection.find_one({"myfield": {"$exists": True}}, sort=[("myfield", 1)])["myfield"]

For more information on sorting see:

• Use Indexes to Sort Query Results

• What is the compare order for BSON types?

StackExchange Database Administrators Q#108113, answer score: 11