Yes exactly, imagine and hotel vanish, and it became into an apartment, i
know is a weird situation but the code is just an example.
example, we have these records:
Person table:
id = 1, person_name = "john", accommodation_id =1
accommodation table:
accommodation_id =1
accommodation_type = "hotel"
address = "street xxx"
hotel_name = "Hotel xxx"
So the idea is to get convert in:
accommodation_id =1 #dont need to be the same, but
need to keep the same relationship with Person table
accommodation_type = "apartment"
address = "street xxx" #keep the same
apartm_name = "Apartment xxx" #delete fields from Hotel table
and add from Apartment table
I hope now is a little more clear the example, but I said is just an
educative code :)
El viernes, 8 de mayo de 2015, 21:30:45 (UTC+2), Michael Bayer escribió:
>
>
>
> On 5/8/15 2:41 PM, Carlus wrote:
>
> Hello,
> Sorry I couldnt find info about in google neither in the documentation,
> I have a model structure like this one:
>
> class Person(Base):
> __tablename__ = 'person' id = Column(Integer, primary_key=True,
> nullable=False)
> person_name = Column(String, nullable=False)
>
> accommodation_id = Column(Integer, ForeignKey("accommodation.id"))
> accommodation = relationship("Accommodation", backref="people")
>
> def __init__(self, person_name):
> self.person_name = person_name
>
> class Accommodation(Base):
> __tablename__ = 'accommodation' __mapper_args__ = {
> 'polymorphic_identity':'accommodation', 'polymorphic_on':
> 'accommodation_type'} id = Column(Integer, primary_key=True)
> accommodation_type = Column(String(32))
> address = Column(String)
>
> class Hotel(Accommodation):
> __tablename__ = 'hotel' __mapper_args__ = {'polymorphic_identity':
> 'hotel' } id = Column(Integer, ForeignKey('accommodation.id'),
> primary_key=True)
> hotel_name = Column(String)
>
> def __init__(self, name, address):
> self.hotel_name = name
> self.address = address
> class Apartment(Accommodation):
> __tablename__ = 'apartment' __mapper_args__ = {
> 'polymorphic_identity': 'apartment' } id = Column(Integer,
> ForeignKey('accommodation.id'), primary_key=True)
> apartm_name = Column(String)
>
> def __init__(self, name, address):
> self.apartm_name = name
> self.address = address
>
>
> Where each Person is associate to some accommodation (thanks to
> polymorphic can be Hotel or Apartment), each accommodation can have more
> than one Person.
>
> Im having problems when I try to update some record in the table
> accommodation, mainly when for example updating the accomodation_type (an
> Apartment became into a Hotel, where would get new records in Hotel and
> would delete any info from the record in Apartment and keeping the same id,
> address, and relationship with People.
>
> I'm not sure what angle you are coming from. Did you want to emit an
> UPDATE for accomodation_type? That would be awkward; it means a Hotel
> vanishes and becomes an Apartment.
>
> Do you mean, you just want to take a Person, associated with some Hotel,
> and move that Person to an Apartment? That would just be an UPDATE of
> Person.accomodation_id. Just change the Person.accommodation attribute to
> the parent record you want.
>
> Not sure what you mean. You'd need to illustrate what rows you are
> looking to modify for me to understand which one you are getting at.
>
>
>
>
>
>
>
> --
> You received this message because you are subscribed to the Google Groups
> "sqlalchemy" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to sqlalchemy+...@googlegroups.com <javascript:>.
> To post to this group, send email to sqlal...@googlegroups.com
> <javascript:>.
> Visit this group at http://groups.google.com/group/sqlalchemy.
> For more options, visit https://groups.google.com/d/optout.
>
>
>
--
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sqlalchemy+unsubscr...@googlegroups.com.
To post to this group, send email to sqlalchemy@googlegroups.com.
Visit this group at http://groups.google.com/group/sqlalchemy.
For more options, visit https://groups.google.com/d/optout.
