This solution works great and it's quick:
from sqlalchemy.sql.expression import func
def ascii(arg):
return func.to_ascii(func.convert_to(arg, "'latin2'"), "'latin2'")
Thanks Michael!
On Jul 17, 5:20 pm, Michael Bayer <[email protected]> wrote:
> On Jul 17, 2009, at 4:54 AM, [email protected] wrote:
>
>
>
>
>
> > Hi.
>
> > I want to create a function or operator, that will convert column or
> > string from utf-8 encoding to ascii.
> > I'm not sure, how function / operators work in SA. So let's start from
> > the beginnig:
> > 1) using postgresql 8.3, sqlalchemy 0.5.3
>
> > 2) had created function in pgsql:
> > CREATE FUNCTION to_ascii(bytea, name)
> > RETURNS text AS 'to_ascii_encname' LANGUAGE internal RETURNS NULL ON
> > NULL INPUT;
>
> > 3) converting from utf-8 to ascii:
> > to_ascii(convert_to('čačašaša','latin2'), 'latin2')
> > result: cacasasa
>
> > 4) using it like this:
> > ... WHERE to_ascii(convert_to(<column_name>,'latin2'), 'latin2') ILIKE
> > to_ascii(convert_to(<non_ascii_str>,'latin2'), 'latin2')
>
> > 5) my vision is to use it like this:
> > session
> > .query(Client).filter( ascii(Client.name).ilike(ascii(name)).all
> > ()
> > or
> > session.query(Client).filter( ascii(Client.name).ascii_ilike(name).all
> > ()
> > or something other :)
>
> if you can make just a single "ascii()" stored procedure, then you can
> say:
>
> query(Client).filter(func.ascii("foo") == "bar")
>
> or you can combine those
>
> def ascii(arg):
> return func.to_ascii(func.convert_to(arg, "latin2"))
>
> otherwise you can use ext.compiler:
>
> from sqlalchemy.sql.expression import Function
> from sqlalchemy.ext.compiler import compiles
>
> class ascii_op(Function):
> def __init__(self, val, enc='latin2'):
> self.val = val
> self.enc = enc
>
> @compiles(ascii_op)
> def compile_ascii_op(element, compiler, **kw):
> return "to_ascii(convert_to(%(val)s,'%(enc)s'), '%(enc)s')" %
> element.__dict__
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