On Tuesday, August 18, 2015 at 11:24:08 PM UTC-6, Michael Bayer wrote:
>
>
>
> On 8/18/15 8:57 PM, Frank Horowitz wrote:
>
> Hi All,
>
> A noob question, that I've been struggling with off and on for a while.
> I'm pretty sure that I'm missing something obvious...
>
> I'm creating tables and their entries "on the fly" programmatically, and
> need to control the table names.
>
> I understand how to define declarative classes as follows:
> Base = declarative_base()
> levels_name = "foobar"
> class Level(Base):
> __tablename__ = levels_name
> height = Column(Float)
> That works well when the static string "foobar" is in the class definition
> module.
>
> What I can't figure out is how to name a table at "construction time" with
> a dynamic string. In other words, how do I specify a tablename when I first
> _use_ a declarative class?
>
> A perfect scenario for me would be something like:
> Base = declarative_base()
> class Level(Base):
> height = Column(Float)
>
> lvl = Level.set_tablename('foobar')
>
> lvl.height = 100.
>
> and have that show up in a table 'foobar', but I can't figure out any way
> to code set_tablename() ...
>
> it doesn't work that way. The tables in your schema are supposed to be
> fixed. If you want to map a new class to a new table, you can do that with
> mixins:
>
>
> class Level(object):
> id = Column(Integer, primary_key=True)
> height = Column(Float)
>
>
>
> class LevelFoobar(Base, Level):
> __tablename__ = 'foobar'
>
> class LevelBat(Base, Level):
> __tablename__ = 'bat'
>
>
> Is this significantly different from using __abstract__? e.g.
>
class Level(Base):
__abstract__ = True
id = Column(Integer, primary_key=True)
height = Column(Float)
class LevelFoobar(Level):
__tablename__ = 'foobar'
class LevelBat(Level):
__tablename__ = 'bat'
>
>
>
>
> In case it matters, my backend is Postgres 9.4.0.1 ...
>
> What am I missing?
>
> TIA for any advice!
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