python - 为什么我从 mongoalchemy 得到 ExtraValueException？

Question

这是我的类(class):

class Presentation(db.Document):
    title = db.StringField(max_length=120, required=True)
    author = db.StringField (required=True)
    pages = db.DocumentField(Page, required=False)
    tags = db.StringField(max_length=120, required=False)
    id = db.IntField(required=True)
    currentPage = db.IntField()
def __str__(self):
     return 'Title:%s author:%s  id:%d currentPage:%d' % ( self.title, self.author,self.id,self.currentPage)

当我从 mongo shell 使用它时，一切似乎都很好:

db.Presentation.find({id:2})

{ "_id" : ObjectId("4e9cdddd0ad5c97ee6000000"), 
"author" : "admin", "currentPage" : 3, "id" : 2, 
"pages" : { "content" : "", "pagenum" : 0 }, "title" : "dd" }

但是当我使用 MongoAlchemy 时，

p = query.filter(Presentation.id==2).first()

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "build/bdist.macosx-10.7-intel/egg/mongoalchemy/query.py", line 136, in first
File "build/bdist.macosx-10.7-intel/egg/mongoalchemy/query.py", line 388, in next
File "build/bdist.macosx-10.7-intel/egg/mongoalchemy/document.py", line 318, in unwrap
File "build/bdist.macosx-10.7-intel/egg/mongoalchemy/document.py", line 152, in __init__

mongoalchemy.exceptions.ExtraValueException: currentPage

Answer 1

对于任何其他有 ExtraValueException 的人，如果您在类定义中放置一个额外的逗号，您也会看到此错误。例如，如果您有:

...
pages = db.DocumentField(Page, required=False),
tags = db.StringField(max_length=120, required=False)
...

尝试使用页面或标签会产生 ExtraValueException。

这是我在痛苦中学到的。