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?
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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