Gotcha. Thanks Michael. Once I get the code working I'll post it here. Off to bed now, though.
Cheers, Tony On Thursday, February 13, 2014 8:49:14 PM UTC-5, Michael Bayer wrote: > > everything in python is ultimately in a namespace, the names are strings, > the values are the objects. > > like if you had “myapp.model” as a module, and in that module were Study > and Site, you could say: > > from myapp import model > Study = getattr(model, “Study”) > > same thing. > > If you want to poke into the registry of class names in declarative, you > can look inside of Base._decl_class_registry: > > def query(clsname, colname): > cls = Base._decl_class_registry[clsname] > col = getattr(cls, colname) > > q = query(cls).filtert(cls.foo == ‘bar’).order_by(col) > > > this kind of thing is very easy in Python once you get the central idea > that everything in Python is the same kind of object each with a name. > > > > On Feb 13, 2014, at 7:56 PM, Tony Garcia <tny...@gmail.com <javascript:>> > wrote: > > Actually, now I see that your suggestion would get me the column object > (not a string), but it would still restrict me to the study table. > > > On Thu, Feb 13, 2014 at 7:53 PM, Tony Garcia <tny...@gmail.com<javascript:> > > wrote: > >> Oops -- disregard the [start:end] at the end of the query and replace >> that with .all() >> >> >> On Thu, Feb 13, 2014 at 7:50 PM, Tony Garcia <tny...@gmail.com<javascript:> >> > wrote: >> >>> Hmm.. I see what you're saying, but the column can be from any of the >>> tables queried from, not just the Study table. So it could be >>> Study.study_id, System.system_name, Site.site_id, etc. Also won't that >>> getattr() call just return a string? I was under the impression that you >>> had to pass a column object to order_by(). So if implemented the solution >>> for dynamic sort direction given in the stackoverflow link above (which >>> takes advantage of the fact that you can access the .asc() or .desc() >>> methods >>> as attributes on the column object), I have this: >>> >>> def my_query(sort_direction='asc'): >>> column_sorted = getattr(Study.study_id, sort_direction)() >>> >>> query = Study.query.options( >>> db.joinedload(Study.system), >>> db.joinedload(Study.site)).\ >>> filter(System.system_id==41).\ >>> order_by(column_sorted)[start:end] >>> return query >>> >>> How can I modify this so that it doesn't just sort on Study.study_id and >>> my method signature would be my_query(sort_column, sort_direction)? >>> Maybe this isn't possible using the ORM and I have to dip down into the >>> SQL expression language, but I thought I'd ask. >>> >>> Thanks. >>> >>> >>> On Thu, Feb 13, 2014 at 7:08 PM, Michael Bayer >>> <mik...@zzzcomputing.com<javascript:> >>> > wrote: >>> >>>> >>>> On Feb 13, 2014, at 6:21 PM, Tony Garcia <tny...@gmail.com<javascript:>> >>>> wrote: >>>> >>>> > Hello, >>>> > I'm new to SQLAlchemy and have searched high and low for a solution >>>> to my problem so I'm hoping someone here can help. I have a query where I >>>> need to apply the 'order by' clause dynamically (both the column and the >>>> direction). So a 'static' version of my query would be: >>>> > >>>> > studies = session.query(Study).options( >>>> > joinedload(Study.system), >>>> > joinedload(Study.site)). >>>> > filter(System.system_id=41). >>>> > order_by(Study.study_id.desc()). >>>> > all() >>>> > >>>> > However the order can be asc or desc and it could be any column from >>>> the 3 tables. I found this post on Stackoverflow which helps with a >>>> dynamic >>>> sort direction (asc, desc), but it doesn't help me with the dynamic column: >>>> > >>>> > >>>> http://stackoverflow.com/questions/20904226/python-sqlalchemy-dynamic-order-by >>>> >>>> “dynamic” attribute access in Python is using the getattr() builtin >>>> function: >>>> >>>> def my_query(order_by_column): >>>> >>>> query = >>>> session.query(Study).filter(Study.system_id=41).order_by(getattr(Study, >>>> order_by_column)) >>>> >>>> that seems like what you’re asking, hope it helps. >>>> >>>> >>>> >>> >> > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sqlalchemy+...@googlegroups.com <javascript:>. > To post to this group, send email to sqlal...@googlegroups.com<javascript:> > . > Visit this group at http://groups.google.com/group/sqlalchemy. > For more options, visit https://groups.google.com/groups/opt_out. > > > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/groups/opt_out.
