Running some code immediately before a Datastore put()?
Nickolas Daskalou
class MyModel(db.Model):
something = db.StringProperty()
something_hash = db.StringProperty()
def generate_hash(self):
self.something_hash = sha1(self.something)
I want generate_hash() to be automatically called just before the entity is put() into the Datastore, without the developer having to explicitly call entity.generate_hash().
I know I can create a put() method that makes such a call and then calls put() on the superclass, but (a) is that the best way to do it, and (b) if the put() is part of a batch put (eg. via db.put(entities)), will the put() method of each model instance still be called?
Nick
Eric Ka Ka Ng
http://code.google.com/appengine/articles/hooks.html
- eric
2010/1/14 Nickolas Daskalou <ni...@daskalou.com>:
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Devel63
I've been faced with your exact situation. I have to say I don't
understand PreCallHook, and maybe that would be the best approach, but
here's what I do know.
Overriding "put" is a bad idea, and as you point out, the override
will not be called in a batch put.
I found that the most elegant solution was to derive a new type of
db.Property, and override its get_value_for_datastore. Then GAE will
automatically do what you want regardless of how the entity is being
put.
On Jan 14, 1:51 am, Eric Ka Ka Ng <ngk...@gmail.com> wrote:
> would a PreCallHook works for your case?
>
> http://code.google.com/appengine/articles/hooks.html
>
> - eric
>
> 2010/1/14 Nickolas Daskalou <n...@daskalou.com>:
Nickolas Daskalou
I'll try and get PreCallHook working because that would allow me to add a "pre_put()" method to my Models, and then using these PreCallHooks I can call pre_put() for each of the entities being put into the Datastore.
Failing that, I'll create a new derived property for my Model and do as Devel63 said.
Nickolas Daskalou
4th code snippet, shouldn't the very first line:
def path_appengine():
be moved to the bottom, just above this line:
apiproxy_stub_map.apiproxy.GetPreCallHooks().Append(....)
?
风笑雪
http://blog.notdot.net/2009/12/Most-popular-metrics-in-App-Engine
2010/1/15 Nickolas Daskalou <ni...@daskalou.com>:
