Hello,
Our data model for a structure named PlateWell in our software utilizes a
singly linked-list structure with a field for a parent PlateWell. We are
adding another field pointing to the root PlateWell of the link list to
improve runtime of certain important operations, however the relationships
are not loading. Here is the abridged model.
class PlateWell(db.Model):
__tablename__ = 'plate_wells'
id = db.Column(db.Integer, primary_key=True)
parent_well_id = db.Column(db.Integer, db.ForeignKey('plate_wells.id'),
index=True)
root_well_id = db.Column(db.Integer, db.ForeignKey('plate_wells.id'),
index=True)
parent_well = db.relationship(
'PlateWell', uselist=False, lazy='noload', remote_side=[id],
foreign_keys=[parent_well_id])
root_well = db.relationship(
'PlateWell', uselist=False, lazy='noload', remote_side=[id],
foreign_keys=[root_well_id])
At the root entry, the root_well_id is equal to id and parent_well_id is
set to None.
Prior to adding the root relationship, the model loaded the parent_well
relationship without the foreign_keys kwarg. This relationship was fully
functional.
Now, any time a plate well is loaded via a query like
well = PlateWell.query.filter(PlateWell.id == well.plate_well_id).one()
both parent_well and root_well are set to None, despite both foreign key id
fields containing an id that does relate to another entry. We've attempted
adding explicit primaryjoin kwargs, expiring the session to clear the
cache, but neither seems to work. Is there a trick to loading multiple
self-referential relationships or some other change we can make to properly
load these relationships?
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