[sqlalchemy] how to make many-to-many links against the same class with an association table
Hi,
I've two classes CourseSet and CanonicalCourse (with the same parent)
which need to be connected in a many-to-many relationship. But these
classes are mapped on the same table, thus definition of the
association table seems redondant:
assoc_course_set_canonical_table = Table(
'CM_COURSE_SET_CANON_ASSOC_T', Base.metadata,
Column('CANON_COURSE', Integer,
ForeignKey('CM_MEMBER_CONTAINER_T.MEMBER_CONTAINER_ID')),
Column('COURSE_SET', Integer,
ForeignKey('CM_MEMBER_CONTAINER_T.MEMBER_CONTAINER_ID'))
)
But i can't define the relationship between. I've the error:
Could not determine join condition between parent/child tables on
relationship CourseSet.canonicalCourses. Specify a 'primaryjoin'
expression. If 'secondary' is present, 'secondaryjoin' is needed as
well.
I must have miss something: i've tried several possibilities with
primaryjoin and secondaryjoin but nothing work. Is it because i'm
refering at the same foreign key in the associative table ?
Thank you.
Julien.
PS: The code for my two classes ('#' comments the two lines with the problem)
class CourseSet(AbstractContainer):
parent_id = Column('PARENT_COURSE_SET', Integer,
ForeignKey('CM_MEMBER_CONTAINER_T.ENTERPRISE_ID'))
children = relationship(CourseSet, backref=backref('parent',
remote_side=AbstractContainer.eid))
#canonicalCourses = relationship(CanonicalCourse,
#secondary=assoc_course_set_canonical_table)
@classproperty
def __mapper_args__(self):
args = dict()
args.update(AbstractContainer.__mapper_args__)
args.update({'polymorphic_identity':
'org.sakaiproject.coursemanagement.impl.CourseSetCmImpl'})
return args
class CanonicalCourse(AbstractContainer):
@classproperty
def __mapper_args__(self):
args = dict()
args.update(AbstractContainer.__mapper_args__)
args.update({'polymorphic_identity':
'org.sakaiproject.coursemanagement.impl.CanonicalCourseCmImpl'})
return args
PS: the parents of these classes:
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(Base,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 }
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Re: [sqlalchemy] Self-referential object failed with heritance
Argh yes you're right. Thank you.
Julien.
On Tue, Sep 28, 2010 at 11:57 PM, Michael Bayer
mike...@zzzcomputing.com wrote:
On Sep 28, 2010, at 5:50 PM, Julien Iguchi-Cartigny wrote:
Hi,
I'm trying to declare a adjacency list as follow:
class CourseSet(AbstractContainer):
parent_id = Column('PARENT_COURSE_SET', Integer,
ForeignKey('CM_MEMBER_CONTAINER_T.ENTERPRISE_ID'))
children = relationship(CourseSet, backref=backref('parent',
remote_side=AbstractNamed.eid))
OK sorry, you're really working the mixins to the Nth degree here. The
columns that are on CourseSet are relative to the mapped class. The
Column() object on AbstractNamed gets copied when declarative sees it. So
the correct column to place on remote_side would be AbstractContainer.eid,
since AbstractContainer is the class that's mapped to the table which
contains ENTERPRISE_ID.
�...@classproperty
def __mapper_args__(self):
args = dict()
args.update(AbstractContainer.__mapper_args__)
args.update({'polymorphic_identity':
'org.sakaiproject.coursemanagement.impl.CourseSetCmImpl'})
return args
But I couldn't succeed, i've the following error message:
sqlalchemy.exc.ArgumentError: Relationship CourseSet.parent could not
determine any local/remote column pairs from remote side argument
set([Column('ENTERPRISE_ID', String(length=255, convert_unicode=False,
assert_unicode=None, unicode_error=None,
_warn_on_bytestring=False), )])
I've tried to use
http://www.sqlalchemy.org/docs/orm/relationships.html#adjacency-list-relationships
but with no success. The only not-classical thing is the use of
AbstractNamed.eid (a field from a parent class), is there an impact ?
Cheers,
Julien.
PS: other parent objects:
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)
def __repr__(self):
return AbstractPersistent('%s','%s', '%s','%s','%s') % \
(self.version, self.last_modified_by,
self.last_modified_date,
self.created_by, self.created_date)
class AbstractNamed(AbstractPersistent):
eid = Column('ENTERPRISE_ID', String(255))
title = Column('TITLE', String(255))
description = Column('DESCRIPTION', String(255))
def __repr__(self):
return AbstractNamed('%s','%s', '%s') % \
(self.eid, self.title, self.description) + \
super(AbstractNamed, self).__repr__()
class AbstractContainer(Base,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 }
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[sqlalchemy] Re: polymorhic_identity not working
Hello Michael,
Sorry I missing something but still trap in this problem.
As far as I am:
class AbstractContainer(Base,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(AbstractContainer):
@classproperty
def __mapper_args__(self):
args = dict()
args.update(AbstractContainer.__mapper_args__)
args.update({'polymorphic_identity':
'org.sakaiproject.coursemanagement.impl.CourseSetCmImpl'})
return args
The inheritance pass is : Course - AbstractContainer - AbstractNamed
- AbstractPersistence (see my first email for the definitions of the
last two classes).
Still having some trouble:
sqlalchemy.exc.ArgumentError: Column 'VERSION' on class class
'__main__.CourseSet' conflicts with existing column
'CM_MEMBER_CONTAINER_T.VERSION'
It I understand correctly, AbstractContainer has already mapped all
columns declared in parent classes. So CourseSet tries to remap
everything (it herits from Base) but it fails because all column are
already mapped.
So I must say something like hey, let just reuse mapping and table
definitions from AbstractContainer but how can i do this ?
It seems it is very simple from the POV of the documentation, so I
must deduce the problem comes from the multiple inheritance.
Cheers,
Julien.
PS: This is the full listing of my code:
from sqlalchemy import create_engine, Column, String, Date, Integer
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.ext.declarative import has_inherited_table
from sqlalchemy.util import classproperty
engine = create_engine(
'mysql://xxx:y...@localhost:3306/zzz?charset=utf8use_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)
def __repr__(self):
return AbstractPersistent('%s','%s', '%s','%s','%s') % \
(self.version, self.last_modified_by,
self.last_modified_date,
self.created_by, self.created_date)
class AbstractNamed(AbstractPersistent):
eid = Column('ENTERPRISE_ID', String(255))
title = Column('TITLE', String(255))
description = Column('DESCRIPTION', String(255))
def __repr__(self):
return AbstractNamed('%s','%s', '%s') % \
(self.eid, self.title, self.description) + \
super(AbstractNamed, self).__repr__()
class AbstractContainer(Base,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 AcademicSession(Base,AbstractNamed):
__tablename__ = 'CM_ACADEMIC_SESSION_T'
id = Column('ACADEMIC_SESSION_ID',Integer,primary_key=True)
start_date = Column('START_DATE', Date)
end_date = Column('END_DATE', Date)
def __repr__(self):
return AcademicSession('%s','%s', '%s') % \
(self.id, self.start_date, self.end_date) + \
super(AcademicSession, self).__repr__()
class CourseSet(AbstractContainer):
@classproperty
def __mapper_args__(self):
args = dict()
args.update(AbstractContainer.__mapper_args__)
args.update({'polymorphic_identity':
'org.sakaiproject.coursemanagement.impl.CourseSetCmImpl'})
return args
if __name__ == __main__:
Session = sessionmaker(bind=engine)
session = Session()
academic_sessions = session.query(AcademicSession).all()
print(academic_sessions)
course_sets = session.query(CourseSet).all()
print(course_sets)
On 27 sep, 23:55, Michael Bayer mike...@zzzcomputing.com wrote:
On Sep 27, 2010, at 5:10 PM, Julien Iguchi-Cartigny 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.
Your original setup seems as though you'd like both CourseSet and
CanonicalCourse to be mapped to the same table using single table
inheritance. Therefore they both must extend a class that is mapped to the
target table. So in this case you'd like AbstractContainer to be mapped,
meaning the Base superclass should be moved from CourseSet and
CanonicalCourse onto AbstractContainer.
You can then query for AbstractContainer subclasses using
session.query(AbstractContainer).
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
Re: [sqlalchemy] Re: polymorhic_identity not working
Thank you for your fast reply and bug fix. I will test this tonight.
Cheers,
Julien.
On Tue, Sep 28, 2010 at 6:46 PM, Michael Bayer mike...@zzzcomputing.com wrote:
this is a bug, ticket #1930, fixed in r36755ba72782. Note that a similar
issue exists for joined table inheritance, and a scheme like the below will
continue to fail if __tablename__ is added to subclasses (this is ticket
#1931). The specific scheme is that the attribute name of the column in
the mixin does not match the column name itself.
http://www.sqlalchemy.org/trac/ticket/1930
http://www.sqlalchemy.org/trac/ticket/1931
On Sep 28, 2010, at 12:06 PM, Julien Iguchi-Cartigny wrote:
Hello Michael,
Sorry I missing something but still trap in this problem.
As far as I am:
class AbstractContainer(Base,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(AbstractContainer):
�...@classproperty
def __mapper_args__(self):
args = dict()
args.update(AbstractContainer.__mapper_args__)
args.update({'polymorphic_identity':
'org.sakaiproject.coursemanagement.impl.CourseSetCmImpl'})
return args
The inheritance pass is : Course - AbstractContainer - AbstractNamed
- AbstractPersistence (see my first email for the definitions of the
last two classes).
Still having some trouble:
sqlalchemy.exc.ArgumentError: Column 'VERSION' on class class
'__main__.CourseSet' conflicts with existing column
'CM_MEMBER_CONTAINER_T.VERSION'
It I understand correctly, AbstractContainer has already mapped all
columns declared in parent classes. So CourseSet tries to remap
everything (it herits from Base) but it fails because all column are
already mapped.
So I must say something like hey, let just reuse mapping and table
definitions from AbstractContainer but how can i do this ?
It seems it is very simple from the POV of the documentation, so I
must deduce the problem comes from the multiple inheritance.
Cheers,
Julien.
PS: This is the full listing of my code:
from sqlalchemy import create_engine, Column, String, Date, Integer
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.ext.declarative import has_inherited_table
from sqlalchemy.util import classproperty
engine = create_engine(
'mysql://xxx:y...@localhost:3306/zzz?charset=utf8use_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)
def __repr__(self):
return AbstractPersistent('%s','%s', '%s','%s','%s') % \
(self.version, self.last_modified_by,
self.last_modified_date,
self.created_by, self.created_date)
class AbstractNamed(AbstractPersistent):
eid = Column('ENTERPRISE_ID', String(255))
title = Column('TITLE', String(255))
description = Column('DESCRIPTION', String(255))
def __repr__(self):
return AbstractNamed('%s','%s', '%s') % \
(self.eid, self.title, self.description) + \
super(AbstractNamed, self).__repr__()
class AbstractContainer(Base,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 AcademicSession(Base,AbstractNamed):
__tablename__ = 'CM_ACADEMIC_SESSION_T'
id = Column('ACADEMIC_SESSION_ID',Integer,primary_key=True)
start_date = Column('START_DATE', Date)
end_date = Column('END_DATE', Date)
def __repr__(self):
return AcademicSession('%s','%s', '%s') % \
(self.id, self.start_date, self.end_date) + \
super(AcademicSession, self).__repr__()
class CourseSet(AbstractContainer):
�...@classproperty
def __mapper_args__(self):
args = dict()
args.update(AbstractContainer.__mapper_args__)
args.update({'polymorphic_identity':
'org.sakaiproject.coursemanagement.impl.CourseSetCmImpl'})
return args
if __name__ == __main__:
Session = sessionmaker(bind=engine)
session = Session()
academic_sessions = session.query(AcademicSession).all()
print(academic_sessions)
course_sets = session.query(CourseSet).all()
print(course_sets)
On 27 sep, 23:55, Michael Bayer mike...@zzzcomputing.com wrote:
On Sep 27, 2010, at 5:10 PM, Julien Iguchi-Cartigny wrote:
But How can i do ? It seems i need to define the table in
AsbtractContainer but every time I've
[sqlalchemy] Self-referential object failed with heritance
Hi,
I'm trying to declare a adjacency list as follow:
class CourseSet(AbstractContainer):
parent_id = Column('PARENT_COURSE_SET', Integer,
ForeignKey('CM_MEMBER_CONTAINER_T.ENTERPRISE_ID'))
children = relationship(CourseSet, backref=backref('parent',
remote_side=AbstractNamed.eid))
@classproperty
def __mapper_args__(self):
args = dict()
args.update(AbstractContainer.__mapper_args__)
args.update({'polymorphic_identity':
'org.sakaiproject.coursemanagement.impl.CourseSetCmImpl'})
return args
But I couldn't succeed, i've the following error message:
sqlalchemy.exc.ArgumentError: Relationship CourseSet.parent could not
determine any local/remote column pairs from remote side argument
set([Column('ENTERPRISE_ID', String(length=255, convert_unicode=False,
assert_unicode=None, unicode_error=None,
_warn_on_bytestring=False), )])
I've tried to use
http://www.sqlalchemy.org/docs/orm/relationships.html#adjacency-list-relationships
but with no success. The only not-classical thing is the use of
AbstractNamed.eid (a field from a parent class), is there an impact ?
Cheers,
Julien.
PS: other parent objects:
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)
def __repr__(self):
return AbstractPersistent('%s','%s', '%s','%s','%s') % \
(self.version, self.last_modified_by,
self.last_modified_date,
self.created_by, self.created_date)
class AbstractNamed(AbstractPersistent):
eid = Column('ENTERPRISE_ID', String(255))
title = Column('TITLE', String(255))
description = Column('DESCRIPTION', String(255))
def __repr__(self):
return AbstractNamed('%s','%s', '%s') % \
(self.eid, self.title, self.description) + \
super(AbstractNamed, self).__repr__()
class AbstractContainer(Base,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 }
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Re: [sqlalchemy] Re: polymorhic_identity not working
OK working, have an other problem but I will open a new thread about it.
Thank you.
Julien.
On 09/28/2010 09:20 PM, Julien Iguchi-Cartigny wrote:
Thank you for your fast reply and bug fix. I will test this tonight.
Cheers,
Julien.
On Tue, Sep 28, 2010 at 6:46 PM, Michael Bayer mike...@zzzcomputing.com
wrote:
this is a bug, ticket #1930, fixed in r36755ba72782. Note that a similar
issue exists for joined table inheritance, and a scheme like the below will
continue to fail if __tablename__ is added to subclasses (this is ticket
#1931). The specific scheme is that the attribute name of the column in
the mixin does not match the column name itself.
http://www.sqlalchemy.org/trac/ticket/1930
http://www.sqlalchemy.org/trac/ticket/1931
On Sep 28, 2010, at 12:06 PM, Julien Iguchi-Cartigny wrote:
Hello Michael,
Sorry I missing something but still trap in this problem.
As far as I am:
class AbstractContainer(Base,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(AbstractContainer):
@classproperty
def __mapper_args__(self):
args = dict()
args.update(AbstractContainer.__mapper_args__)
args.update({'polymorphic_identity':
'org.sakaiproject.coursemanagement.impl.CourseSetCmImpl'})
return args
The inheritance pass is : Course - AbstractContainer - AbstractNamed
- AbstractPersistence (see my first email for the definitions of the
last two classes).
Still having some trouble:
sqlalchemy.exc.ArgumentError: Column 'VERSION' on class class
'__main__.CourseSet' conflicts with existing column
'CM_MEMBER_CONTAINER_T.VERSION'
It I understand correctly, AbstractContainer has already mapped all
columns declared in parent classes. So CourseSet tries to remap
everything (it herits from Base) but it fails because all column are
already mapped.
So I must say something like hey, let just reuse mapping and table
definitions from AbstractContainer but how can i do this ?
It seems it is very simple from the POV of the documentation, so I
must deduce the problem comes from the multiple inheritance.
Cheers,
Julien.
PS: This is the full listing of my code:
from sqlalchemy import create_engine, Column, String, Date, Integer
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.ext.declarative import has_inherited_table
from sqlalchemy.util import classproperty
engine = create_engine(
'mysql://xxx:y...@localhost:3306/zzz?charset=utf8use_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)
def __repr__(self):
return AbstractPersistent('%s','%s', '%s','%s','%s') % \
(self.version, self.last_modified_by,
self.last_modified_date,
self.created_by, self.created_date)
class AbstractNamed(AbstractPersistent):
eid = Column('ENTERPRISE_ID', String(255))
title = Column('TITLE', String(255))
description = Column('DESCRIPTION', String(255))
def __repr__(self):
return AbstractNamed('%s','%s', '%s') % \
(self.eid, self.title, self.description) + \
super(AbstractNamed, self).__repr__()
class AbstractContainer(Base,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 AcademicSession(Base,AbstractNamed):
__tablename__ = 'CM_ACADEMIC_SESSION_T'
id = Column('ACADEMIC_SESSION_ID',Integer,primary_key=True)
start_date = Column('START_DATE', Date)
end_date = Column('END_DATE', Date)
def __repr__(self):
return AcademicSession('%s','%s', '%s') % \
(self.id, self.start_date, self.end_date) + \
super(AcademicSession, self).__repr__()
class CourseSet(AbstractContainer):
@classproperty
def __mapper_args__(self):
args = dict()
args.update(AbstractContainer.__mapper_args__)
args.update({'polymorphic_identity':
'org.sakaiproject.coursemanagement.impl.CourseSetCmImpl'})
return args
if __name__ == __main__:
Session = sessionmaker(bind=engine)
session = Session()
academic_sessions = session.query(AcademicSession).all()
print(academic_sessions)
course_sets = session.query(CourseSet).all()
print(course_sets)
On 27 sep, 23:55, Michael Bayer mike...@zzzcomputing.com wrote:
On Sep 27
Re: [sqlalchemy] polymorhic_identity not working
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 ?
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=utf8use_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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Re: [sqlalchemy] polymorhic_identity not working
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=utf8use_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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Re: [sqlalchemy] polymorhic_identity not working
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=utf8use_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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[sqlalchemy] polymorhic_identity not working
Hi,
I'm trying to use polymorphic_on with several inheritances:
engine = create_engine(
'mysql://xxx:y...@localhost:3306/zzz?charset=utf8use_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'}
As you can see, `CourseSet` contains all the columns of its parents
and has the column `CLASS_DISCR` sets to
`'org.sakaiproject.coursemanagement.impl.CourseSetCmImpl'`.
But when it make a query fro all `CourseSet`:
Session = sessionmaker(bind=engine)
session = Session()
course_sets = session.query(CourseSet).all()
print(course_sets)
It returns all the entries of `'CM_MEMBER_CONTAINER_T'`, but I want
only the ones with `CLASS_DISCR` set to
`'org.sakaiproject.coursemanagement.impl.CourseSetCmImpl'`
Any ideas ? I'm using version 0.6.4
Julien.
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