相当于对象.最新()应用内引擎

你最好的办法是实施 latest() classmethod直接打开 MyObject 就这样说吧

latest = MyObject.latest()

Query 班级。

我想我会明白实现这个功能有多难看。这里有一个mixin类,如果你真的想调用它的话,可以使用它 MyObject.all().latest() :

class LatestMixin(object):
    """A mixin for db.Model objects that will add a `latest` method to the
    `Query` object returned by cls.all(). Requires that the ORDER_FIELD
    contain the name of the field by which to order the query to determine the
    latest object."""

    # What field do we order by?
    ORDER_FIELD = None

    @classmethod
    def all(cls):
        # Get the real query
        q = super(LatestMixin, cls).all()
        # Define our custom latest method
        def latest():
            if cls.ORDER_FIELD is None:
                raise ValueError('ORDER_FIELD must be defined')
            return q.order('-' + cls.ORDER_FIELD).get()
        # Attach it to the query
        q.latest = latest
        return q

# How to use it
class Foo(LatestMixin, db.Model):
    ORDER_FIELD = 'timestamp'
    timestamp = db.DateTimeProperty(auto_now_add=True)

latest = Foo.all().latest()

Query class

按时间排序结果:

MyObject.all().order('-time')

MyObject.all().order('-time')[0]

或

MyObject.all().order('-time').fetch(limit=1)[0]