I've tried to following several examples, for instance this one:
http://stackoverflow.com/questions/1337095/sqlalchemy-inheritance
It seems because i've multiple inheritances, my problem is more
complex than this example, is anyone has an idea why ?
Julien.
On Mon, Sep 27, 2010 at 11:10 PM, Julien Iguchi-Cartigny
<kart...@gmail.com> wrote:
> But How can i do ? It seems i need to define the table in
> AsbtractContainer but every time I've an error about already defined
> column.
>
> Cheers,
>
> Julien.
>
> On Mon, Sep 27, 2010 at 10:30 PM, Michael Bayer
> <mike...@zzzcomputing.com> wrote:
>>
>> On Sep 27, 2010, at 4:21 PM, Julien Iguchi-Cartigny wrote:
>>
>>> Thank you Michael. This solves the problem and... shows a new one.
>>>
>>> So this is my update CourseSet
>>>
>>> class CourseSet(Base,AbstractContainer):
>>>
>>> �...@classproperty
>>> def __mapper_args__(self):
>>> args = dict()
>>> args.update(AbstractContainer.__mapper_args__)
>>> args.update({'polymorphic_identity':
>>> 'org.sakaiproject.coursemanagement.impl.CourseSetCmImpl'})
>>> return args
>>>
>>> Because there is several discriminant values, I need to create other ones:
>>>
>>> class CanonicalCourse(Base,AbstractContainer):
>>>
>>> �...@classproperty
>>> def __mapper_args__(self):
>>> args = dict()
>>> args.update(AbstractContainer.__mapper_args__)
>>> args.update({'polymorphic_identity':
>>> 'org.sakaiproject.coursemanagement.impl.CanonicalCourseCmImpl'})
>>> return args
>>>
>>>
>>> But this last one will fail, i've the following error message:
>>>
>>> sqlalchemy.exc.InvalidRequestError: Table 'CM_MEMBER_CONTAINER_T' is
>>> already defined for this MetaData instance. Specify
>>> 'useexisting=True' to redefine options and columns on an existing
>>> Table object.
>>>
>>> I could use useexisting=True but i don't know if it's the right
>>> solution. Any ideas ?
>>
>> that has to do with a Table() statement, or alternatively how you are
>> configuring __table_name__, neither of which are indicated here, so you need
>> to ensure that distinct table names are used whenever a table name is
>> declared.
>>
>>
>>
>>
>>>
>>> Cheers,
>>>
>>> Julien.
>>>
>>> On Mon, Sep 27, 2010 at 1:02 AM, Michael Bayer <mike...@zzzcomputing.com>
>>> wrote:
>>>>
>>>> On Sep 26, 2010, at 6:38 PM, Julien Iguchi-Cartigny wrote:
>>>>
>>>>> Hi,
>>>>>
>>>>> I'm trying to use polymorphic_on with several inheritances:
>>>>>
>>>>> engine = create_engine(
>>>>> 'mysql://xxx:y...@localhost:3306/zzz?charset=utf8&use_unicode=0',
>>>>> pool_recycle=3600, echo=True)
>>>>>
>>>>> Base = declarative_base()
>>>>>
>>>>> class AbstractPersistent(object):
>>>>> version = Column('VERSION', Integer)
>>>>> last_modified_by = Column('LAST_MODIFIED_BY', String(255))
>>>>> last_modified_date = Column('LAST_MODIFIED_DATE', Date)
>>>>> created_by = Column('CREATED_BY', String(255))
>>>>> created_date = Column('CREATED_DATE', Date)
>>>>>
>>>>> class AbstractNamed(AbstractPersistent):
>>>>> eid = Column('ENTERPRISE_ID', String(255))
>>>>> title = Column('TITLE', String(255))
>>>>> description = Column('DESCRIPTION', String(255))
>>>>>
>>>>> class AbstractContainer(AbstractNamed):
>>>>> __tablename__ = 'CM_MEMBER_CONTAINER_T'
>>>>> id = Column('MEMBER_CONTAINER_ID',Integer,primary_key=True)
>>>>> discriminator = Column('CLASS_DISCR', String(100))
>>>>> __mapper_args__ = {'polymorphic_on': discriminator }
>>>>>
>>>>> class CourseSet(Base,AbstractContainer):
>>>>> __mapper_args__ = {'polymorphic_identity':
>>>>> 'org.sakaiproject.coursemanagement.impl.CourseSetCmImpl'}
>>>>
>>>> AbstractContainer is not mapped, its a mixin, so its __mapper_args__ are
>>>> not used until a subclass of Base is invoked, which starts up a
>>>> declarative mapping. Your only mapped class then is CourseSet, which has
>>>> its own __mapper_args__ , that override those of AbstractContainer - they
>>>> are ignored.
>>>>
>>>> To combine __mapper_args__ from a mapped class with those of a mixin, see
>>>> the example at
>>>> http://www.sqlalchemy.org/docs/orm/extensions/declarative.html?highlight=declarative#combining-table-mapper-arguments-from-multiple-mixins
>>>> . It uses __table_args__ but the same concept of creating a full
>>>> dictionary of arguments applies for __mapper_args__ as well.
>>>>
>>>>
>>>>
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>>>>
>>>
>>>
>>>
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>>
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>
>
>
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