Sorry, that should have been:
existing_creator = DBSession(Creator).query.filter_by(creator=creator).first()
On Monday, August 12, 2013 at 9:49 PM, Tim Van Steenburgh wrote:
> It's not the append that's causing the error, it's the fact that you're
> creating a new Creator() instance, which ultimately results in an INSERT
> statement being issued.
>
> You want to append a Creator instance to `company.creator`, but you don't
> necessarily want to make a new Creator every time you instantiate a Company.
> If a Creator with the given name already exists, you'll want use that instead.
>
> So, roughly:
>
> class Company(Base):
> __tablename__ = "companies"
> id = Column(Integer, primary_key = True)
> company = Column(String(100), unique=True, nullable=False)
> creator = relationship("Creator", backref="companies", cascade="all")
> def __init__(self, company, creator):
> self.company = company
> existing_creator = DBSession(Creator).query.filter_by(name=creator).first()
> self.creator.append(existing_creator or Creator(creator))
>
>
> --
> Tim Van Steenburgh
>
>
>
> On Monday, August 12, 2013 at 9:41 PM, [email protected]
> (mailto:[email protected]) wrote:
>
> > Sorry I don't understand what you're trying to say.
> >
> > If the Creator already exists, and I'm to append it again, isn't that the
> > same as what my code is currently doing? (That is, appending in every
> > instance.) I don't see how this wouldn't result in the same error message.
> >
> > And what would it mean to create a new one and append that? I don't know
> > what this code would look like.
> >
> > Apologies if I'm being dense.
> >
> > On Monday, August 12, 2013 9:33:31 PM UTC-4, Tim wrote:
> > > In `Company.__init__()`, instead of blindly creating a new `Creator`
> > > instance, you need to first query for an existing Creator with that name.
> > > If it exists, append it, otherwise, create a new one and append that.
> > >
> > > --
> > > Tim Van Steenburgh
> > >
> > >
> > > On Monday, August 12, 2013 at 9:26 PM, [email protected] (javascript:)
> > > wrote:
> > >
> > > > I have another question about a piece of code that I posted the other
> > > > day. Namely, I have a one-to-many relationship between Creator and
> > > > Company. A Creator can have a relationship with multiple Companies but
> > > > any one Company can have a relationship with only one Creator.
> > > >
> > > > class Company(Base):
> > > > __tablename__ = "companies"
> > > > id = Column(Integer, primary_key = True)
> > > > company = Column(String(100), unique=True, nullable=False)
> > > > creator = relationship("Creator", backref="companies",
> > > > cascade="all")
> > > >
> > > >
> > > > def __init__(self, company, creator):
> > > > self.company = company
> > > > self.creator.append(Creator(creator))
> > > >
> > > > class Creator(Base):
> > > > __tablename__ = "creators"
> > > >
> > > > company_id = Column(Integer, ForeignKey('companies.id
> > > > (http://companies.id/)'))
> > > > creator = Column(String(100), nullable=False, unique=True)
> > > >
> > > > def __init__(self, creator):
> > > > self.creator = creator
> > > >
> > > >
> > > > So, to create a Company, the code calls company = Company(<company
> > > > name>, <creator name>) and that in turn calls Creator().
> > > >
> > > > The problem is that the Companies get added one by one, and if a new
> > > > company being entered has a Creator with a name of a preexisting
> > > > company, SQLalchemy errors due to the unique=True flag:
> > > >
> > > > sqlalchemy.exc.IntegrityError: (IntegrityError) (1062, "Duplicate entry
> > > > 'Viking' for key 'creator'") 'INSERT INTO creators (company_id,
> > > > creator) VALUES (%s, %s)' (17L, u'Viking')
> > > >
> > > > If unique=True isn't enabled, it will create another Creator of the
> > > > same name. Instead, the code should reflect the additional Company
> > > > assigned to this particular Creator. How might I go about fixing this?
> > > >
> > > > Thanks!
> > > >
> > > > --
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