如何从pymongo聚合中获取结果计数？

Question

I am trying to get the result count of a pymongo aggregate method. The aggregate method returns a command_cursor object but according to the pymongo docs only the cursor object has a count() method. How do I get the count of the result of an aggregate function without using any kind of loop?

Answer 1

I think you should return count from your aggregation:

pipeline = [
     {"$match": YOURQUERY},
     {"$group": {"_id": groupby, "count": {"$sum":1}}}, # this returns count
     {YOUR_PIPELINES}
]
cursor = db.collection.aggregate(pipeline)

Answer 2

You can do:

result = list(db.collection.aggregate([...]))
print(len(result))