Oh. This isn't the same example that I was talking about. From the example
in the doc, you are allowed to have the column and the synonym have the
same name, but your example has _job_status for the column and job_status
for the synonym. when I do it your way, inspect shows _job_status as an attr
>>> inspect(mc).attrs.keys()
['job_status', '_job_status', 'id']
The way listed in the docs had me believing that you could change these
lines from your example:
_job_status = Column("job_status", String(50))
job_status = synonym("_job_status")
to
job_status = Column("job_status", String(50))
job_status = synonym("_job_status")
no leading underscore. When doing it this way, the job_status column is
never detected or created. I just realized that the example I'm following
is literally the section for "map_column", so does that mean that
functionality isn't supported anymore?
here's the link to the section I'm speaking about specifically:
http://docs.sqlalchemy.org/en/latest/orm/mapped_attributes.html#sqlalchemy.orm.synonym.params.map_column
The example is what I was copying because the description of what it does
is what I was hoping to achieve.
On Wednesday, January 24, 2018 at 5:45:51 PM UTC-8, Mike Bayer wrote:
> On Wed, Jan 24, 2018 at 7:25 PM, dykang <dyk...@gmail.com <javascript:>>
> wrote:
> > Thank you for the tip, but If I remove map_column=True from the example,
> > then inspect returns the correct listing, but when I load an object from
> the
> > db, neither job_status nor _job_status are accessible on the object. It
> > seems to work on assignment, but not on load from db. Is there something
> > more I have to do?
>
> here is a complete example:
>
> from sqlalchemy import *
> from sqlalchemy.orm import *
> from sqlalchemy.ext.declarative import declarative_base
>
> Base = declarative_base()
>
>
> class MyClass(Base):
> __tablename__ = 'my_table'
> id = Column(Integer, primary_key=True)
> _job_status = Column("job_status", String(50))
> job_status = synonym("_job_status")
>
> e = create_engine("sqlite://", echo=True)
> Base.metadata.create_all(e)
>
> s = Session(e)
> mc = MyClass(job_status="some status")
> s.add(mc)
> s.commit()
> s.close()
>
> mc = s.query(MyClass).first()
> assert mc.job_status == "some status"
>
>
>
>
> >
> >>>> a = session.query(myclass.MyClass).get(1)
> >>>> a
> > <MyClass(id=1)>
> >>>> a.id
> > 1
> >>>> a.__mapper__.columns
> > <sqlalchemy.util._collections.OrderedProperties object at
> 0x7fa91f92c0c0>
> >>>> a.__mapper__.columns.keys()
> > ['id']
> >>>> a.job_status
> > Traceback (most recent call last):
> > File "<stdin>", line 1, in <module>
> > File
> >
> "virtualenv/workspace/local/lib/python2.7/site-packages/sqlalchemy/orm/attributes.py",
>
>
> > line 298, in __get__
> > return self.descriptor.__get__(instance, owner)
> > File
> >
> "virtualenv/workspace/local/lib/python2.7/site-packages/sqlalchemy/orm/descriptor_props.py",
>
>
> > line 58, in fget
> > return getattr(obj, self.name)
> > AttributeError: 'MyClass' object has no attribute '_job_status'
> >
> >
> > On Wednesday, January 24, 2018 at 2:33:39 PM UTC-8, Mike Bayer wrote:
> >>
> >> remove map_column=True, will update the docs now.
> >>
> >> On Wed, Jan 24, 2018 at 5:01 PM, dykang <dyk...@gmail.com> wrote:
> >> > I was trying to use a synonym to map a column through a setter/getter
> >> > (with
> >> > use of descriptor kwarg). I'm not sure if I'm doing this right, but I
> >> > tried
> >> > to copy/paste the example out of the documentation, and it didn't
> work.
> >> > Could someone point out what I'm doing wrong or point me at a better
> way
> >> > to
> >> > do what I want? I've tried with 1.1.12 and 1.2.1 with python 2.7.
> >> >
> >> > this is the entirety of what I'm trying to do:
> >> > ------------------------------------------------------
> >> >
> >> > from sqlalchemy.ext import declarative
> >> > Base = declarative.declarative_base()
> >> > from sqlalchemy import *
> >> > from sqlalchemy.orm import synonym
> >> >
> >> > class MyClass(Base):
> >> > __tablename__ = 'my_table'
> >> > id = Column(Integer, primary_key=True)
> >> > job_status = Column(String(50))
> >> > job_status = synonym("_job_status", map_column=True)
> >> >
> >> > ------------------------------------------------------
> >> >
> >> > This fails because the synonym won't compile. It appears that the
> >> > job_status
> >> > Column value has been overridden by the synonym before it's had a
> chance
> >> > to
> >> > create the synonym to the original. It seems I can get around this
> by
> >> > not
> >> > using the map_column value and just renaming the column to
> _job_status,
> >> > but
> >> > I was hoping that using sqlalchemy.inspect(row_instance).attrs would
> >> > only
> >> > return job_status, and not _job_status (I'm not even sure if this is
> >> > true,
> >> > it was just a guess on how it might work and what I wanted to happen)
> >> >
> >> > Traceback (most recent call last):
> >> > File "<stdin>", line 1, in <module>
> >> > File
> >> >
> >> >
> "/virtualenv/workspace/local/lib/python2.7/site-packages/sqlalchemy/ext/declarative/api.py",
>
>
> >> > line 64, in __init__
> >> > _as_declarative(cls, classname, cls.__dict__)
> >> > File
> >> >
> >> >
> "/virtualenv/workspace/local/lib/python2.7/site-packages/sqlalchemy/ext/declarative/base.py",
>
>
> >> > line 88, in _as_declarative
> >> > _MapperConfig.setup_mapping(cls, classname, dict_)
> >> > File
> >> >
> >> >
> "/virtualenv/workspace/local/lib/python2.7/site-packages/sqlalchemy/ext/declarative/base.py",
>
>
> >> > line 116, in setup_mapping
> >> > cfg_cls(cls_, classname, dict_)
> >> > File
> >> >
> >> >
> "/virtualenv/workspace/local/lib/python2.7/site-packages/sqlalchemy/ext/declarative/base.py",
>
>
> >> > line 148, in __init__
> >> > self._early_mapping()
> >> > File
> >> >
> >> >
> "/virtualenv/workspace/local/lib/python2.7/site-packages/sqlalchemy/ext/declarative/base.py",
>
>
> >> > line 151, in _early_mapping
> >> > self.map()
> >> > File
> >> >
> >> >
> "/virtualenv/workspace/local/lib/python2.7/site-packages/sqlalchemy/ext/declarative/base.py",
>
>
> >> > line 576, in map
> >> > **self.mapper_args
> >> > File "<string>", line 2, in mapper
> >> > File
> >> >
> >> >
> "/virtualenv/workspace/local/lib/python2.7/site-packages/sqlalchemy/orm/mapper.py",
>
>
> >> > line 692, in __init__
> >> > self._configure_properties()
> >> > File
> >> >
> >> >
> "/virtualenv/workspace/local/lib/python2.7/site-packages/sqlalchemy/orm/mapper.py",
>
>
> >> > line 1383, in _configure_properties
> >> > self._configure_property(key, prop, False)
> >> > File
> >> >
> >> >
> "/virtualenv/workspace/local/lib/python2.7/site-packages/sqlalchemy/orm/mapper.py",
>
>
> >> > line 1677, in _configure_property
> >> > prop.set_parent(self, init)
> >> > File
> >> >
> >> >
> "/virtualenv/workspace/local/lib/python2.7/site-packages/sqlalchemy/orm/descriptor_props.py",
>
>
> >> > line 626, in set_parent
> >> > % (self.name, parent.mapped_table.description, self.key))
> >> > sqlalchemy.exc.ArgumentError: Can't compile synonym '_job_status':
> no
> >> > column on table 'my_table' named 'job_status'
> >> >
> >> > --
> >> > SQLAlchemy -
> >> > The Python SQL Toolkit and Object Relational Mapper
> >> >
> >> > http://www.sqlalchemy.org/
> >> >
> >> > To post example code, please provide an MCVE: Minimal, Complete, and
> >> > Verifiable Example. See http://stackoverflow.com/help/mcve for a
> full
> >> > description.
> >> > ---
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> >> > "sqlalchemy" group.
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> >> > an
> >> > email to sqlalchemy+...@googlegroups.com.
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> >> > For more options, visit https://groups.google.com/d/optout.
> >
> > --
> > SQLAlchemy -
> > The Python SQL Toolkit and Object Relational Mapper
> >
> > http://www.sqlalchemy.org/
> >
> > To post example code, please provide an MCVE: Minimal, Complete, and
> > Verifiable Example. See http://stackoverflow.com/help/mcve for a full
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--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
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