Thank you Mike !
Le mardi 20 juin 2017 21:23:01 UTC+3, Mike Bayer a écrit :
>
>
>
> On 06/20/2017 02:08 PM, yoch....@gmail.com <javascript:> wrote:
> > Hi,
> >
> > I wish to have a two-levels inheritance, but I don't know how to
> proceed.
> > The docs says that "only one discriminator column or SQL expression may
> > be configured for the entire inheritance hierarchy".
> >
> > I tried with this example (mixing joined and single inheritances) :
> >
> > |
> > classPerson(Base):
> > __tablename__ ='person'
> >
> > id =Column(Integer,primary_key=True)
> > type =Column(String(50),nullable=False)
> > name =Column(String(50))
> >
> > __mapper_args__ ={
> > 'polymorphic_identity':'person',
> > 'polymorphic_on':type
> > }
> >
> > classManager(Person):
> > __tablename__ ='manager'
> >
> > id =Column(ForeignKey('person.id'),primary_key=True)
> > manager_name =Column(String(30))
> >
> > __mapper_args__ ={
> > 'polymorphic_identity':'manager',
> > }
> >
> > classEngineerBase(Person):
> > __tablename__ ='engineer'
> >
> > id =Column(ForeignKey('person.id'),primary_key=True)
> > engineer_name =Column(String(30))
> >
> > classEngineerType1(EngineerBase):
> >
> > __mapper_args__ ={
> > 'polymorphic_identity':'engineer_t1',
> > }
> >
> > classEngineerType2(EngineerBase):
> >
> > __mapper_args__ ={
> > 'polymorphic_identity':'engineer_t2',
> > }
> > |
> >
> > It seems to work, but it this correct ?
>
> it's correct, you only have one "polymorphic_on" set up, and that's what
> that means.
>
>
> >
> > --
> > 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 -
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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