>
>
> you'd need to implement a generate_relationship function as described at
> http://docs.sqlalchemy.org/en/rel_1_0/orm/extensions/automap.html#custom-relationship-arguments
>
> which applies the rules you want in order to establish those relationships
> that you'd like to be one-to-one.
>
>
Yeah, that's what I tried to do here, but it appeared to do nothing. That
documentation isn't entirely clear I'm afraid. The direction input doesn't
have an interaction.ONETOONE option, so I tried to find an alternative way
of identifying which tables needed a one-to-one relationship. Having a
look, I don't think this function works as is because I don't define the
pair of tables (from local_cls, referred_cls) that are in a one-to-one. I
only define one in my onetoones list.
onetoones = ['file']
def _gen_relationship(base, direction, return_fn, attrname, local_cls,
referred_cls, **kw):
if local_cls.__table__.name in onetoones:
kw['uselist'] = False
# make use of the built-in function to actually return the result.
return generate_relationship(base, direction, return_fn, attrname,
local_cls, referred_cls, **kw)
>
>
> Here is what I'm trying so far, but it's not working.
>>
>
>
> I don't see anything obviously wrong with it but you'd want to step
> through with pdb.set_trace() to ensure every aspect of it is doing what
> you'd expect. Otherwise "not working" can mean lots of things.
>
>
Ok. Well I'll keep digging around.
>
>
>>
>>
>>
>
>
>> onetoones = ['file']
>>
>> def _gen_relationship(base, direction, return_fn, attrname, local_cls,
>> referred_cls, **kw):
>> if local_cls.__table__.name in onetoones:
>> kw['uselist'] = False
>> # make use of the built-in function to actually return the result.
>> return generate_relationship(base, direction, return_fn, attrname,
>> local_cls, referred_cls, **kw)
>>
>> def camelizeClassName(base, tablename, table):
>> return str(tablename[0].upper() + re.sub(r'_([a-z])', lambda m:
>> m.group(1).upper(), tablename[1:]))
>>
>> _pluralizer = inflect.engine()
>> def pluralize_collection(base, local_cls, referred_cls, constraint):
>> referred_name = referred_cls.__name__
>> uncamelized = re.sub(r'[A-Z]', lambda m: "_%s" % m.group(0).lower(),
>> referred_name)[1:]
>> pluralized = _pluralizer.plural(uncamelized)
>> return pluralized
>>
>> # Grabs engine
>> db = DatabaseConnection()
>> engine = db.engine
>>
>> # Selects schema and automaps it.
>> metadata = MetaData(schema='mangadapdb')
>> Base = automap_base(bind=engine, metadata=metadata)
>>
>> # Pre-define Dap class. Necessary so automap knows to join this table to
>> a declarative base class from another schema
>> class Dap(Base):
>> __tablename__ = 'dap'
>>
>> cube_pk = Column(Integer, ForeignKey(datadb.Cube.pk))
>> cube = relationship(datadb.Cube, backref='dap', uselist=False)
>>
>> # Prepare the base
>> Base.prepare(engine, reflect=True, classname_for_table=camelizeClassName,
>> name_for_collection_relationship=pluralize_collection,
>> generate_relationship=_gen_relationship)
>>
>> # Explicitly declare classes
>> for cl in Base.classes.keys():
>> exec('{0} = Base.classes.{0}'.format(cl))
>>
>>
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