Pymongo: TypeError: if no direction is specified, key_or_list must be an instance of list

使用pymongo對某一字段進行sort時，報錯 

TypeError: if no direction is specified, key_or_list must be an instance of list

問題代碼：

items = db.symptomAssociation.find({ 'result.pre.0':{'$regex':input_text}}).sort({'result.0.confidence':-1})

更正後：

items = db.symptomAssociation.find({ 'result.pre.0':{'$regex':input_text}}).sort([('result.0.confidence',-1)])