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.
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