google-app-engine - GQL 按日期选择

Question

我有这个模型:

class Entry(db.Model):
    title = db.StringProperty()
    url = db.URLProperty()
    date = db.DateTimeProperty(auto_now=True)
    image = db.URLProperty()
    weight = db.IntegerProperty()
    category = db.StringProperty()
    desc = db.TextProperty()

我每天都有很多条目，如何使用 GGL 只选择今天的条目？因为这样的查询不会返回任何结果(但我知道有结果):

SELECT * FROM Entry WHERE category = 'news' and date = '2012-03-12' ORDER BY weight DESC

Answer 1

它不是保存为字符串，而是保存为类似日期时间的对象。

The right-hand side of a comparison can be one of the following:

• a datetime, date, or time literal, with either numeric values or a string representation, in the following forms:

  DATETIME(year, month, day, hour, minute, second)
  DATETIME('YYYY-MM-DD HH:MM:SS')
  DATE(year, month, day)
  DATE('YYYY-MM-DD')
  TIME(hour, minute, second)
  TIME('HH:MM:SS')

http://code.google.com/appengine/docs/python/datastore/gqlreference.html

所以在您的示例中，使用其中任何一个。

date = DATE('2012-03-12')
date = DATE(2012,03,12)

对于datetime，时间默认设置为00:00，所以相等比较会失败所以你必须使用>来比较

SELECT * FROM Entry WHERE date > DATETIME(yyyy,mm,dd)