Andy (Zenom) wrote:
> I got the server side one created in schema cms, function name is
> slugify.
>
> I am trying to figure out how to let sqlalchemy know about the
> function and the schema its in. On postgresql I can do like SELECT
> cms.slugify(title) FROM cms.tablename, and it returns the slugified
> title, but to get that in sqlalchemy? Sorry should have been more
> clear. I was "assuming" I needed to somehow create my own sqlalchemy
> function, but havn't found the right answer yet.
so that's column_property(func.cms.slugify(title)) .
>
> On Feb 2, 10:50 am, "Michael Bayer" <mike...@zzzcomputing.com> wrote:
>> Andy (Zenom) wrote:
>> > The one thing that is frustrating is it is re-querying the database.
>> > So if I create a simple server side function how would I do that? I am
>> > currently using trunk.
>>
>> how to create the server side function or how to use it from SQLA ? the
>> column_property() thing is where you'd use func.foo().
>>
>>
>>
>>
>>
>> > On Feb 2, 8:57 am, Andy <andy.hol...@belator.com> wrote:
>> >> Thanks, that worked like a charm. Look forward to your PyCon
>> >> presentation.
>>
>> >> On Feb 2, 12:56 am, Michael Bayer <mike...@zzzcomputing.com> wrote:
>>
>> >> > On Feb 1, 2010, at 9:24 PM, Andy (Zenom) wrote:
>>
>> >> > > I don't know if my terminology is correct etc. But the basic idea
>> is
>> >> > > the following.
>>
>> >> > > In my model I have something like
>>
>> >> > > from mylib.helpers import slugify
>>
>> >> > > class MyModel(Base):
>> >> > > __tablename__ = "testing"
>>
>> >> > > id = Column(Integer, primary_key)
>> >> > > title = Column(Unicode)
>> >> > > description = Column(Unicode)
>>
>> >> > > @property
>> >> > > def slug(self):
>> >> > > return slugify(self.title)
>>
>> >> > > Now I want to be able to do something like.
>> >> > > session.query(MyModel.id, MyModel.title, MyModel.slug).all()
>>
>> >> > > The table obviously doesn't have a slug column, I just want to
>> >> return
>> >> > > my title as a "pseudo-column" named slug, with it passed through
>> my
>> >> > > slugify method first.
>>
>> >> > > I tried to do something like the following:
>>
>> >> > > @synonym_for("title")
>> >> > > @property
>> >> > > def slug(self):
>> >> > > return slugify(self.title)
>>
>> >> > > And this did not work. It seems to just return another column
>> just
>> >> > > like title (not sent through slugify first). Any idea how I can
>> do
>> >> > > what I am looking for?
>>
>> >> > part of the approach depends on if "slugify" can be defined as a
>> SQL
>> >> function or if it must be executed in Python. If the latter, you
>> >> probably want MyModel.slug to resolve into a column that also defines
>> >> a custom type.
>>
>> >> > Assuming its a Python function, note that your column can't be used
>> >> effectively in a comparison operation, like "MyModel.slug == 'foo'",
>> >> since the slugify() operation would have to be applied in aggregate.
>>
>> >> > Anyway assuming non-SQL function, here's a hack I came up with that
>> >> will do it:
>>
>> >> > from sqlalchemy import *
>> >> > from sqlalchemy.orm import *
>> >> > from sqlalchemy.ext.declarative import declarative_base
>> >> > from sqlalchemy.sql.expression import _UnaryExpression
>> >> > from sqlalchemy.types import UserDefinedType
>>
>> >> > Base = declarative_base()
>>
>> >> > def slugify(text):
>> >> > return "SLUG !" + text
>>
>> >> > class MySlugType(UserDefinedType):
>> >> > def result_processor(self, dialect, coltype):
>> >> > return slugify
>>
>> >> > class MyModel(Base):
>> >> > __tablename__ = "testing"
>>
>> >> > id = Column(Integer, primary_key=True)
>> >> > title = Column(Unicode)
>> >> > description = Column(Unicode)
>>
>> >> > slug = column_property(_UnaryExpression(title,
>> >> type_=MySlugType()))
>>
>> >> > engine = create_engine('sqlite://', echo=True)
>> >> > Base.metadata.create_all(engine)
>> >> > session = sessionmaker(engine)()
>>
>> >> > session.add(MyModel(title=u'title', description=u'description'))
>> >> > session.commit()
>>
>> >> > print session.query(MyModel.title, MyModel.slug).all()
>>
>> >> > > --
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