如何在pymongo中获取数组长度？

from pymongo import MongoClient

# 连接MongoDB数据库
client = MongoClient('mongodb://localhost:27017/')
db = client['mydatabase']
collection = db['mycollection']

# 查询包含数组字段的文档，并获取数组长度
result = collection.aggregate([
    {
        '$project': {
            'array_length': {'$size': '$my_array_field'}
        }
    }
])

# 打印结果
for doc in result:
    print(doc['array_length'])