On Mar 31, 8:33 am, Jonathan LaCour <[EMAIL PROTECTED]>
wrote:
> Bud P. Bruegger wrote:
> > Many thanks for the answer.
>
> > Another hopefully quick question:
>
> > Is it possible to select a subset of columns in a query of an
> > Entity subclass? Kind of
>
> > EntitySubClass.query.select([EntitySubClass.c.col1,
> > EntitySubClass.c.col2]).all()
>
> Yes, there are several ways to do it. In addition to the previous
> link to the wiki about setting up deferred column groups, you can
> manually define which columns get deferred/loaded at query time:
>
> from sqlalchemy.orm import defer
>
> ...
>
> class Person(Entity):
> name = Field(String(64))
> age = Field(Integer)
> life_story = Field(Text)
> giant_picture = Field(Binary)
>
> ...
>
> people = Person.query.options(
> defer('life_story'),
> defer('giant_picture')
> ).all()
>
> Alternatively, you can drop down to the table objects themselves,
> and manually create your query:
>
> from sqlalchemy import select
>
> results = select(
> [Person.table.c.name, Person.table.c.age]
> ).execute().fetchall()
>
> for result in results:
> print result[0], result[1]
>
> I hope this helps!
>
> --
> Jonathan LaCourhttp://cleverdevil.org
...snip...
I've amended the wiki page to include this additional information.
http://elixir.ematia.de/trac/wiki/Recipes/DeferredColumns
-jeff
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