擅长:python、mysql、java
<p>也许您想添加一个计算属性:</p>
<p><a href="https://developers.google.com/appengine/docs/python/ndb/properties#computed" rel="nofollow">https://developers.google.com/appengine/docs/python/ndb/properties#computed</a></p>
<blockquote>
<p>Computed properties (ComputedProperty) are read-only properties whose
value is computed from other property values by an
application-supplied function. The computed value is written to the
Datastore so that it can be queried and displayed in the Datastore
viewer, but the stored value is ignored when the entity is read back
from the Datastore; rather, the value is recomputed by calling the
function whenever the value is requested.</p>
</blockquote>
<pre><code>class SomeEntity(ndb.Model):
name = ndb.StringProperty()
name_lower = ndb.ComputedProperty(lambda self: self.name.lower())
x = SomeEntity(name='Nick')
</code></pre>
<p>因此,您需要某种类型的函数,而不是上面的lower(),它计算并更新模型中新的LatFloat,longfoat。因此,您可以将数据保存为两个浮点和一个字符串。我相信你只需添加这个,你现有的数据不会受到影响,相反,当你试图阅读或搜索这些数据时,它会被计算并返回。在</p>