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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