我想对.find()
Python中的mongoDB使用这样的代码:
import pymongo
client = pymongo.MongoClient('mongodb://localhost:27000')
db = client['responsi']
cursor = db['produk']
for x in cursor.find({"pricing.pct_savings":{"$gt":25}}).sort({"pricing.pct_savings":-1}):
print(x)
但是,它显示出这样的错误:
Traceback (most recent call last):
File "Find.py", line 7, in <module>
for x in cursor.find({"pricing.pct_savings":{"$gt":25}}).sort({"pricing.pct_savings":-1}):
File "G:\PROGRAM FILES\Python\lib\site-packages\pymongo\cursor.py", line 708, in sort
keys = helpers._index_list(key_or_list, direction)
File "G:\PROGRAM FILES\Python\lib\site-packages\pymongo\helpers.py", line 69, in _index_list
raise TypeError("if no direction is specified, "
TypeError: if no direction is specified, key_or_list must be an instance of list
如何解决这个问题?谢谢!抱歉,我英语成绩不好。
相对于蒙戈外壳,pymongo需要key
和direction
作为参数传递给排序方法(或列表,但这是另一种形式是不相关的,你现在,我会告诉它太)
所以你的查询实际上应该是cursor.find({"pricing.pct_savings":{"$gt":25}}).sort("pricing.pct_savings", pymongo.DESCENDING)
另一种形式是获取字段名称和方向的元组列表,并允许您按多个字段进行排序,例如 collection.find().sort([('my_field_1',pymongo.DESCENDING), ('my_field_2',pymongo.ASCENDING)])
您可以在这里https://api.mongodb.com/python/current/api/pymongo/collection.html#pymongo.ASCENDING找到ASCENDING
和DESCENDING
常量
BTW(与您的原始问题无关)db['produk']
实际上是一个集合,而不是游标,因此最好将其称为集合而不是游标。游标是什么find()
回报
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