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4885Re: [Cheetahtemplate-discuss] NameMapper issues with Google App Engine db.Model objects

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  • R. Tyler Ballance
    Aug 14, 2010
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      On Sat, 14 Aug 2010, Chad George wrote:

      > In AppEngine, db.Model objects unfortunately implement a "has_key()"
      > method that checks if a model instance has had a key assigned to it
      > yet.
      >
      > This causes NameMapper.py to determine that it should use dictionary
      > style access instead of getattr().


      I /think/ you can circumvent this functionality by disabling autocalling, I've
      not used AppEngine, but you might try that:

      http://cheetahtemplate.org/docs/users_guide_html_multipage/language.namemapper.autocalling.html




      >
      > I think there are two possible solutions:
      > 1. use hasattr(obj, "keys") instead of hasattr(obj, "has_key")
      > 2. try to use hasattr()/getattr() ... before trying dictionary access
      >
      > I tested #1 and it seems to work...but I'm too new to Cheetah to know
      > if there are unintended consequences
      >
      > For #2 the biggest issue I see is in _valueForName() ... you
      > definitely don't want to hit the exception on every access to a
      > dictionary, so you'd need another call to hasattr() ... which
      > presumably was just done before getting to _valueForName() in the
      > first place.
      >
      > Probably not a big deal either way. I'm not sure if there was a
      > pre-existing design decision to try dictionary access before attribute
      > access.
      >
      > - Chad
      >
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      Cheers,
      -R. Tyler Ballance
      --------------------------------------
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