On Dec 27, 2010, at 5:30 PM, lycovian wrote:
> A models __init__ method works great to setup attributes on the model
> that don't exist in the underlying table when creating a model.
> Unfortunately, if you are retrieving the model though the __init__
> method isn't triggered. Is there something like an event that can be
> hooked such that code can be run when the model is instantiated via
> retrieval from the underlying DB?
>
> I see events in the event system (looking at 0.7b1) but nothing that
> looks to be triggered when the model is loaded into memory.
>
> If there isn't an event for this what would be the recommended way to
> accomplish this? Thanks for any help that can be rendered.
the traditional way to get at this functionality since 0.5 is via
@reconstructor:
http://www.sqlalchemy.org/docs/orm/mapper_config.html?highlight=reconstructor#constructors-and-object-initialization
http://www.sqlalchemy.org/docs/orm/mapper_config.html?highlight=reconstructor#sqlalchemy.orm.reconstructor
The event itself is public in 0.6 as MapperExtension.reconstruct_instance:
http://www.sqlalchemy.org/docs/orm/interfaces.html#sqlalchemy.orm.interfaces.MapperExtension.reconstruct_instance
in 0.7, the new interface publishes this event as "on_load()" and also
introduces "on_refresh()":
http://www.sqlalchemy.org/docs/07/orm/events.html#sqlalchemy.orm.events.InstanceEvents.on_load
>
> Cheers.
>
> Mike
>
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