Filter Key

[Max]

Hi,

I'm trying to filter by Key, but it's not working. I have searched in the documents, but there is nothing useful (or understandable for me).

My code is:

class ModificaHandler(webapp.RequestHandler):

def get(self, domain):

appo = self.request.get('domain')

risto = db.Query(RISTORANTI).filter("key =", appo)

self.response.out.write(template.render('risto.html',{'risto':risto}))

I can't understand why. Please help.

Max

[Jeff Schnitzer]

The key field is "__key__" (two underscores on each side).

Jeff

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[Max]

Thanks, but now I have something new.

BadFilterError: BadFilterError: invalid filter: __key__ filter value must be a Key; received  (a str).

I'm taking the key from the domain name:

def main():

application = webapp.WSGIApplication([

('/ristorante', RistoHandler),

(r'/(.*)/modifica', ModificaHandler),

('/.*', MainHandler)],

debug=True)

wsgiref.handlers.CGIHandler().run(application)

Can you help me with this too?

Thanks

Max

[Amy Unruh]

Max,

It looks as though you may be intending to fetch an object based on its key name rather than its key?  If you build an object using a specified key name, e.g.:

  MyModel.get_or_insert(key_name='some_key')

Then you can fetch it like this:

  myobject = MyModel.get_by_key_name('some_key')

or  alternately:

  k = db.Key.from_path('MyModel', 'some_key')

  myobject = db.get(k)

  

 –Amy

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[Max]

I've tried your method but I'm still having an error.

In my template I'm bulding a link by the key:

<a href=\"/{{ elemento.key}}/modifica\">  Modifica/Commenti </a>

then:

def main():

application = webapp.WSGIApplication([

('/ristorante', RistoHandler),

(r'/(.*)/modifica', ModificaHandler),

('/.*', MainHandler)],

debug=True)

wsgiref.handlers.CGIHandler().run(application)

then:

class ModificaHandler(webapp.RequestHandler):

def get(self, domain):

appo = self.request.get('domain')

risto = RISTORANTI.get_by_key_name(appo)

self.response.out.write(template.render('risto.html',{ 'risto':risto}))

The error is:

Traceback (most recent call last):
  File "C:\Program Files\Google\google_appengine\google\appengine\ext\webapp\__init__.py", line 634, in __call__
    handler.get(*groups)
  File "C:\Users\Massimiliano\Desktop\AppEngine Application\Thepietronis\main.py", line 39, in get
    risto = RISTORANTI.get_by_key_name(appo)
  File "C:\Program Files\Google\google_appengine\google\appengine\ext\db\__init__.py", line 1188, in get_by_key_name
    for name in key_names]
  File "C:\Program Files\Google\google_appengine\google\appengine\api\datastore_types.py", line 489, in from_path
    ValidateString(id_or_name, 'name')
  File "C:\Program Files\Google\google_appengine\google\appengine\api\datastore_types.py", line 158, in ValidateString
    raise exception('%s must not be empty.' % name)
BadValueError: name must not be empty.

[Max]

I'm not building the key, but I'm using the given key of the object.

[Max]

Do someone know how to sort it out?

[Amy Unruh]

Max,

It looks like you need to be working with a string-encoded key when you generate the client-side pages, which you can then convert back to a Key server-side as needed.  You can obtain the string-encoded version by passing the Key object to str(). See http://code.google.com/appengine/docs/python/datastore/keyclass.html for details.

 -Amy

On Sun, Oct 23, 2011 at 10:25 PM, Max <massimilia...@gmail.com> wrote:

Do someone know how to sort it out?

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