On Feb 5, 2014, at 9:43 AM, Jude Lucien <jluc...@gmail.com> wrote: > Thanks for your informative answer! > > I have a secondary problem now having changed my model to use declarative > base - as in db.create_all() does not create my tables in the database. > > How can I do this using the declarative base method?
Base.metadata is where you’d call create_all(my engine) from.
>
>
> On 5 February 2014 04:36, Michael Bayer <mike...@zzzcomputing.com> wrote:
>
> On Feb 4, 2014, at 8:20 PM, Jude Lucien <jluc...@gmail.com> wrote:
>
>>
>>
>> I am using SQLAlchemy 0.9 with Python 2.7.6 and Flask.
>>
>> I receive form data, place it into object and add the objects to the
>> session. When I try to do a db.commit() I get a rollback which seems to due
>> to the relationship object in the INSERT statement. The SQL error is as
>> follows:
>>
>> INFO sqlalchemy.engine.base.Engine INSERT INTO site (name, address1,
>> address2, postcode, city, fk_country_id, fk_school_id) VALUES (%(name)s,
>> %(address1)s, %(address2)s, %(postcode)s, %(city)s, %(fk_country_id)s,
>> %(fk_school_id)s) RETURNING site.id
>>
>> INFO sqlalchemy.engine.base.Engine {'city': u'New York', 'fk_school_id':
>> <sqlalchemy.orm.attributes.InstrumentedAttribute object at 0x8c274ac>,
>> 'name': u'Site1', 'address1': u'2 York Way', 'address2': u'', 'postcode':
>> u'12345', 'fk_country_id': u'2'}
>>
>> INFO sqlalchemy.engine.base.Engine ROLLBACK (ProgrammingError) can't adapt
>> type 'InstrumentedAttribute'
>>
>> The relationship code in the model is as follows:
>>
>> class Site(db.Model):
>> id = db.Column(db.Integer, primary_key = True)
>> school = db.relationship('School', backref = 'site', uselist = False)
>>
>> What is it about the relationship object that causes the rollback? I am new
>> to SQLAlchemy and so have followed what it says in the documentation
>> regarding relationships.
>>
>> Both of the data types in the models (Site, School) are ints.
>>
>>
>
>
> there’s nothing wrong with the configuration there, the error has to do with
> the wrong kind of object being assigned to a database row, in this case the
> class-bound attribute.
>
> So basically this:
>
> class Site(Base):
> # …
> fk_school_id = Column(Integer, ForeignKey(…))
>
> class School(Base):
> id = Column(Integer, primary_key=True)
>
> site = Site()
> site.fk_school_id = School.id # <— incorrect, School is a class, not an
> instance of School
>
> session.add(site)
> session.commit()
>
>
> a class-bound attribute like “School.id” is an InstrumentedAttribute. your
> intent here is to assign an integer value to fk_school_id.
>
> But also, when using relationship() you will have an easier time if you work
> with objects rather than foreign key attributes:
>
> some_school = School()
> site.school = some_school
>
>
>
>
>
>
>
>
>
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>
>
>
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