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pythongoogle-app-engineexpando

Clone and Expando class object in Python for App Engine


What is a good way to clone (make a copy of) an Expando class object when using Python on Google App Engine?

I came across some code on here, but unless I'm mistaken, it does not work on expando properties: Copy an entity in Google App Engine datastore in Python without knowing property names at 'compile' time

Thanks!


Solution

  • Here's a revised version of Nick's function that includes dynamic properties:

    def clone_entity(e, **extra_args):
      """Clones an entity, adding or overriding constructor attributes.
    
      The cloned entity will have exactly the same property values as the original
      entity, except where overridden. By default it will have no parent entity or
      key name, unless supplied.
    
      Args:
        e: The entity to clone
        extra_args: Keyword arguments to override from the cloned entity and pass
          to the constructor.
      Returns:
        A cloned, possibly modified, copy of entity e.
      """
      klass = e.__class__
      props = dict((k, v.__get__(e, klass)) for k, v in klass.properties().iteritems())
      props.update(dict([(k, getattr(e, k)) for k in e.dynamic_properties()]))
      props.update(extra_args)
      return klass(**props)