Question

我有一个简单的一对多结构，如下所示：

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

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

我通过他的电子邮件获取用户：

q = User.all() # prepare User table for querying
q.filter("userEmail =", "az@example.com")  # 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

如何按日期订购用户的评论，并将其限制为10条评论？

Answer 1

您需要使用内置key函数的sorted关键字参数，并使用“date”属性作为键：

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

该查询提取用户。您需要对注释执行另一个查询： this_users_comments.order（ '日期'）。极限（10）在this_users_comments中发表评论： ...

使用ReferenceProperty时如何按日期订购？

2 个答案: