Hmm. So I removed the column definitions and it worked just fine. This
doesn't make any sense to me, since this is essentially my original class
definition, and now it works. Maybe I had a type before?, but it didn't
look like it. I'm using a postgreSQL database, and my table definition is
very straightforward. It looks like
CREATE TABLE datadb.sample (pk serial PRIMARY KEY NOT NULL, tileid INTEGER,
nsa_mstar REAL, nsa_id INTEGER, .... bunch of other column definitions )
No my table does not have a logmstar definition. Only mstar. I create the
property in my Sample class definition. This is very strange.
Brian
On Friday, January 15, 2016 at 6:31:23 PM UTC-5, Simon King wrote:
>
> You shouldn’t need to define the columns. Here’s another test script:
>
> ###########################
> import math
>
> import sqlalchemy as sa
> import sqlalchemy.orm as saorm
> from sqlalchemy.ext.hybrid import hybrid_property
> from sqlalchemy.ext.declarative import declarative_base
>
> Base = declarative_base()
>
> engine = sa.create_engine('sqlite:///hybridtest.db')
>
> engine.execute("""
> CREATE TABLE sample (
> pk INTEGER NOT NULL,
> nsa_mstar FLOAT,
> PRIMARY KEY (pk)
> )
> """)
>
> class Sample(Base):
> __tablename__ = 'sample'
> __table_args__ = {'autoload' : True, 'autoload_with': engine}
>
> @hybrid_property
> def nsa_logmstar(self):
> try:
> return math.log10(self.nsa_mstar)
> except ValueError:
> return -9999.0
> except TypeError:
> return None
>
> @nsa_logmstar.expression
> def nsa_logmstar(cls):
> return sa.func.log(cls.nsa_mstar)
>
>
> if __name__ == '__main__':
> sm = saorm.sessionmaker()
> session = sm()
> print session.query(Sample.pk).filter(Sample.nsa_logmstar < 9)
> ###########################
>
> What database are you using, and what is your SQL table definition? Does
> your table already have a nsa_logmstar column? (I don’t think that should
> matter, but it would be worth checking)
>
> Simon
>
>
> > On 15 Jan 2016, at 22:27, Brian Cherinka <havo...@gmail.com
> <javascript:>> wrote:
> >
> > It looks like I needed to define the columns inside my class. That's
> the only difference between your class and mine. And I tested out the
> query and it now works, and returns the correct number of rows.
> >
> > In [4]: print
> > session.query(datadb.Sample.pk).filter(datadb.Sample.nsa_logmstar
> < 9)
> >
> > SELECT datadb.sample.pk AS datadb_sample_pk
> > FROM datadb.sample
> > WHERE log(datadb.sample.nsa_mstar) < %(log_1)s
> >
> > In [6]:
> > len(session.query(datadb.Sample.pk).filter(datadb.Sample.nsa_logmstar
> < 9,datadb.Sample.nsa_mstar > 0).all())
> > Out[6]: 273
> >
> > Do you have any idea why the column definition matters here? Thanks for
> all your help.
> >
> > Brian
> >
> > On Friday, January 15, 2016 at 5:02:03 PM UTC-5, Brian Cherinka wrote:
> > Here is the print immediately after my original class definition:
> >
> > print 'sample nsa log mstar',
> Sample.nsa_logmstar
> >
> > and the result
> >
> > sample nsa log mstar None
> >
> > When I run your script exactly as is, I get the same output as you.
> >
> > When I replace my class definition with yours, inside my code, as
> follows
> >
> > class Sample(Base):
> > __tablename__ = 'sample'
> > __table_args__ = {'autoload' : True, 'schema' : 'mangadatadb'} (I
> needed to add this line in)
> >
> > pk = Column(Integer, primary_key=True)
> > nsa_mstar = Column(Float)
> >
> > @hybrid_property
> > def nsa_logmstar(self):
> > try:
> > return math.log10(self.nsa_mstar)
> > except ValueError:
> > return -9999.0
> > except TypeError:
> > return None
> >
> > @nsa_logmstar.expression
> > def nsa_logmstar(cls):
> > return func.log(cls.nsa_mstar)
> >
> > now the print statement : print 'sample nsa log mstar',
> Sample.nsa_logmstar
> > returns
> >
> > sample nsa log mstar log(mangadatadb.sample.nsa_mstar)
> >
> >
> > On Friday, January 15, 2016 at 4:28:31 PM UTC-5, Simon King wrote:
> > Does my test script produce the right output for you in your
> installation?
> >
> > What does the print statement immediately after the class definition
> produce?
> >
> > Simon
> >
> > > On 15 Jan 2016, at 19:10, Brian Cherinka <havo...@gmail.com> wrote:
> > >
> > > Actually, the class definition is entirely what I posted in the
> original message. I didn't cut anything out of that. I don't define the
> columns in mine, as you did. The property nsa_logmstar is not defined
> anywhere else in the class or in any other place in this code, or in any
> code that interacts with this code.
> > >
> > > 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)
> > >
> > > My database connection is a singleton and my base is defined inside
> that, essentially
> > >
> > > engine = create_engine(database_connection_string)
> > > Base = declarative_base(bind=engine)
> > >
> > > Brian
> > >
> > > On Friday, January 15, 2016 at 9:43:39 AM UTC-5, Simon King wrote:
> > > What happens if you put the print statement immediately after the
> class definition? Is there any chance that you've got "nsa_logmstar = None"
> somewhere in your class definition?
> > >
> > > Here's a test script which appears to work:
> > >
> > > import math
> > >
> > > import sqlalchemy as sa
> > > import sqlalchemy.orm as saorm
> > > from sqlalchemy.ext.hybrid import hybrid_property
> > > from sqlalchemy.ext.declarative import declarative_base
> > >
> > > Base = declarative_base()
> > >
> > > class Sample(Base):
> > > __tablename__ = 'sample'
> > >
> > > pk = sa.Column(sa.Integer, primary_key=True)
> > > nsa_mstar = sa.Column(sa.Float)
> > >
> > > @hybrid_property
> > > def nsa_logmstar(self):
> > > try:
> > > return math.log10(self.nsa_mstar)
> > > except ValueError:
> > > return -9999.0
> > > except TypeError:
> > > return None
> > >
> > > @nsa_logmstar.expression
> > > def nsa_logmstar(cls):
> > > return sa.func.log(cls.nsa_mstar)
> > >
> > >
> > > if __name__ == '__main__':
> > > sm = saorm.sessionmaker()
> > > session = sm()
> > > print session.query(Sample.pk).filter(Sample.nsa_logmstar < 9)
> > >
> > >
> > > And here's the output:
> > >
> > >
> > > SELECT sample.pk AS sample_pk
> > > FROM sample
> > > WHERE log(sample.nsa_mstar) < :log_1
> > >
> > >
> > > Simon
> > >
> > >
> > > On Fri, Jan 15, 2016 at 2:23 PM, Brian Cherinka <havo...@gmail.com>
> wrote:
> > > Ahh. Thanks. Here is the class side then. Still None.
> > >
> > > In [14]: print datadb.Sample.nsa_logmstar
> > > None
> > >
> > > Brian
> > >
> > > On Friday, January 15, 2016 at 8:48:30 AM UTC-5, Simon King wrote:
> > > "Sample()" is an instance. "Sample" is the class. Try:
> > >
> > > print datadb.Sample.nsa_logmstar
> > >
> > > Simon
> > >
> > > On Fri, Jan 15, 2016 at 1:46 PM, Brian Cherinka <havo...@gmail.com>
> wrote:
> > > Hi Simon,
> > >
> > > Printing on the class side, I get
> > >
> > > In [11]: print datadb.Sample().nsa_logmstar
> > > None
> > >
> > > It looks like it's getting set to None (or remaining None). I'm not
> quite sure what this tells me, except that it's not working. Printing on
> in the instance side, I get
> > >
> > > In [12]: print cube.sample[0].nsa_mstar
> > > 1386160000.0
> > >
> > > In [13]: print cube.sample[0].nsa_logmstar
> > > 9.14181336239
> > >
> > > nsa_mstar is a column in my database table, and nsa_logmstar I want to
> be simply the log-base10 of that quantity.
> > >
> > > If this doesn't give any insight, then it will take me some time to
> provide a small script. This code is embedded into a bunch of stuff. But
> I'll work on it.
> > >
> > > Brian
> > >
> > >
> > > On Friday, January 15, 2016 at 5:00:51 AM UTC-5, Simon King wrote:
> > > On Fri, Jan 15, 2016 at 6:16 AM, Brian Cherinka <havo...@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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