On Fri, Jan 15, 2016 at 6:16 AM, Brian Cherinka <havok2...@gmail.com> wrote:
> I'm trying to set up a hybrid property / expression in a custom class,
> that I can use in queries. I think I have the syntax correct, however the
> query returns the entire table, instead of the correct subset of results.
> And the where clause just indicates True rather than the correct
> expression.
>
>
> Here is my hybrid property/expression definition
>
> class Sample(Base,ArrayOps):
> __tablename__ = 'sample'
> __table_args__ = {'autoload' : True, 'schema' : 'datadb'}
>
> def __repr__(self):
> return '<Sample (pk={0},cube={1})'.format(self.pk,self.cube)
>
> @hybrid_property
> def nsa_logmstar(self):
> try: return math.log10(self.nsa_mstar)
> except ValueError as e:
> return -9999.0
> except TypeError as e:
> return None
>
> @nsa_logmstar.expression
> def nsa_logmstar(cls):
> return func.log(cls.nsa_mstar)
>
> The session query is
>
> session.query(Sample.pk).filter(Sample.nsa_logmstar < 9)
>
> But printing it does not show the appropriate condition. I get
>
> SELECT datadb.sample.pk AS datadb_sample_pk,
> FROM datadb.sample
> WHERE true
>
> and the results return the entire table of ~11000 rows instead of the
> expected 272 rows. What's going on here? Everything looks correct to me,
> but I can't figure it out.
>
> I'm expecting the SQL statement to look like this
>
> select s.pk
> from datadb.sample as s
> where log(s.nsa_mstar) < 9;
>
> Any thoughts? Thanks.
>
>
I can't see anything obviously wrong with your code, but it looks like
Sample.nsa_logmstar is not actually resolving to the hybrid property in
your query. What happens if you "print Sample.nsa_logmstar" just before the
query?
Otherwise, please provide a small runnable script that demonstrates the
problem.
Simon
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