如何使用ReferenceProperty按日期排序？

Question

我有一个简单的一对多的结构是这样的：

class User(db.Model): 
    userEmail = db.StringProperty() 

class Comment(db.Model): 
    user = db.ReferenceProperty(User, collection_name="comments") 
    comment = db.StringProperty() 
    date = db.DateTimeProperty() 

我从他的电子邮件获取一个用户：

q = User.all() # prepare User table for querying 
q.filter("userEmail =", "[email protected]") # apply filter, email lookup 
results = q.fetch(1) # execute the query, apply limit 1 
the_user = results[0] # the results is a list of objects, grab the first one 

this_users_comments = the_user.comments # get the user's comments 

如何订购日期用户的意见，并限制它对10条评论？

Answer 1

你将要使用内置sorted功能，并使用“日期”属性的key关键字参数的关键：

import operator 
sorted_comments = sorted(this_users_comments, key=operator.attrgetter("date")) 
# The comments will probably be sorted with earlier comments at the front of the list 
# If you want ten most recent, also add the following line: 
# sorted_comments.reverse() 
ten_comments = sorted_comments[:10] 

Answer 2

该查询获取用户。你需要的意见做另一个查询： this_users_comments.order（“日期”）的限制（10） 在this_users_comments评论： ...