I run into a problem and don't know how to solve it.
The theory is very simple: I habe one base class table with name, id
and type column
The child class shall have a unique type_id (all child_class1 objekt
shall get type_id 7, all child_class2 objekts type_id = 8, ...)
How can I map the base class typ_id to an hard coded value for eahc
class type.
My actual approach does not change the type_id-columns of Objekt and
after saving the objekt the column Objekt.type_id entry is always empty
for all entries :-(
class Objekt(db.Model):
__tablename__ = 'objekt'
def __init__(self,**kwargs):
super().__init__(**kwargs)
id = db.Column(db.Integer, primary_key=True)
typ_id = db.Column(db.Integer, db.ForeignKey('objekt_typ.id'))
typ = db.relationship("ObjektTyp")
name = db.Column(db.String(100))
class ChildClass1(Objekt):
__tablename__ = 'child_class1'
@staticmethod
def typ_id():
return 7
def __init__(self,**kwargs):
super().__init__(**kwargs)
Objekt.typ_id = ChildClass1.typ_id() ### fix type
id = db.Column(db.Integer, db.ForeignKey('objekt.id'),
primary_key=True)
text = db.Column(db.String(255 ), default='')
__mapper_args__ = {
'polymorphic_identity':'child_class1',
}
any ideas where to look? I though on polymorphic_on, but I think that
does not work because of the fact that type_id ha a foreign key ...
right know I get an error:
c = ChildClass()
db.session.add(c)
db.session.commit()
c.typ -> UnmappedColumnError('No column objekt.typ_id is configured on
mapper mapped class ChildClass1->child_class1...')
SirAnn
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