I have two tables, tablet
and correspondent
:
class Correspondent(db.Model, GlyphMixin):
# PK column and tablename etc. come from the mixin
name = db.Column(db.String(100), nullable=False, unique=True)
# association proxy
tablets = association_proxy('correspondent_tablets', 'tablet')
def __init__(self, name, tablets=None):
self.name = name
if tablets:
self.tablets = tablets
class Tablet(db.Model, GlyphMixin):
# PK column and tablename etc. come from the mixin
area = db.Column(db.String(100), nullable=False, unique=True)
# association proxy
correspondents = association_proxy('tablet_correspondents', 'correspondent')
def __init__(self, area, correspondents=None):
self.area = area
if correspondents:
self.correspondents = correspondents
class Tablet_Correspondent(db.Model):
__tablename__ = "tablet_correspondent"
tablet_id = db.Column("tablet_id",
db.Integer(), db.ForeignKey("tablet.id"), primary_key=True)
correspondent_id = db.Column("correspondent_id",
db.Integer(), db.ForeignKey("correspondent.id"), primary_key=True)
# relations
tablet = db.relationship(
"Tablet",
backref="tablet_correspondents",
cascade="all, delete-orphan",
single_parent=True)
correspondent = db.relationship(
"Correspondent",
backref="correspondent_tablets",
cascade="all, delete-orphan",
single_parent=True)
def __init__(self, tablet=None, correspondent=None):
self.tablet = tablet
self.correspondent = correspondent
I can add records to tablet
and correspondent
, and doing e.g. Tablet.query.first().correspondents
simply returns an empty list, as you would expect. If I manually insert a row into my tablet_correspondent
table using existing tablet and correspondent IDs, the list is populated, again as you would expect.
However, if I try to do
cor = Correspondent.query.first()
tab = Tablet.query.first()
tab.correspondents.append(cor)
I get:
KeyError: 'tablet_correspondents'
I'm pretty sure I'm leaving out something fairly elementary here.
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