Perché SQLalchemy caricando solo un'istanza dalla mia relazione molti-a-molti?
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23-12-2019 - |
Domanda
Sto cercando di aggiungere attributi a una relazione molti-to-molti nel mio modello, e ora quando carico un oggetto, sto solo ottenendo un oggetto correlato dalla mia query.
In particolare sto cercando di ottenere tutte le app associate a un determinato backup, e anche la colonna BackupApp.Status.
Ci scusiamo per il dump Info:
So che ho centinaia di relazioni da caricare:
$ sqlite3 dev.db "select count(*) from backups_apps where backup_id = 3 and app_id is not null;"
415
.
Ma ne sto solo ottenendo uno:
{
"children": [
{
"children": [
{
"bundle_id": "com.iojoe.10",
"compressed": 13151750,
"name": "10",
"size": 14458882
}
],
"name": "Games"
}
],
"name": "root"
}
.
I modelli:
# -*- coding: utf-8 -*-
from app_sizer.database import db, CRUDMixin, TimestampMixin, jsonify_plist
from sqlalchemy.ext.associationproxy import association_proxy
class App(db.Model, CRUDMixin, TimestampMixin):
__tablename__ = 'apps'
bundle_id = db.Column(db.String, unique=True, index=True)
app_id = db.Column(db.Integer, unique=True, index=True)
path = db.Column(db.String, unique=True, index=True)
name = db.Column(db.String, index=True)
main_genre = db.Column(db.String, index=True)
compressed_size = db.Column(db.Integer)
full_size = db.Column(db.Integer)
plist = db.Column(db.PickleType)
plist_json = db.Column(db.Text, default=jsonify_plist, onupdate=jsonify_plist)
subgenre_1 = db.Column(db.String, index=True)
subgenre_2 = db.Column(db.String, index=True)
@classmethod
def get_by_bundle_id(cls, bundle_id):
return db.session.query(cls).filter(App.bundle_id == bundle_id).first()
@classmethod
def get_by_path(cls, path):
return db.session.query(cls).filter(App.path == path).first()
@classmethod
def get_all(cls):
return db.session.query(cls).all()
"""
class AppTag(CRUDMixin):
app_id = db.Column(db.Integer, foreign_key='app.id')
user_id = db.Column(db.Integer, foreign_key='user.id')
tag = db.Column(db.String)
"""
# db.Index('idx_tag_user', 'app_tag.user_id', 'app_tag.tag')
class Backup(db.Model, CRUDMixin, TimestampMixin):
__tablename__ = 'backups'
path = db.Column(db.String, unique=True)
name = db.Column(db.String)
notes = db.Column(db.Text)
# Springboard plist
plist = db.Column(db.PickleType)
plist_json = db.Column(db.Text, default=jsonify_plist, onupdate=jsonify_plist)
@classmethod
def get_by_path(cls, path):
return db.session.query(Backup).filter(Backup.path == path).first()
@classmethod
def get_all(cls):
return db.session.query(Backup).all()
# Why does this work but a declarative class doesn't? No idea.
# http://xsnippet.org/359350/
# http://stackoverflow.com/q/5756559/25625
class BackupApp(db.Model, CRUDMixin):
__tablename__ = 'backups_apps'
backup_id = db.Column(db.Integer, db.ForeignKey('backups.id'), nullable=False, default=1)
app_id = db.Column(db.Integer, db.ForeignKey('apps.id'), nullable=False, default=1)
status = db.Column(db.String)
app = db.relationship(App, backref="installed_apps")
backup = db.relationship(Backup, backref="installed_apps")
def __init__(self, app=None, backup=None, status=None):
self.app = app
self.backup = backup
self.status = status
Backup.apps = association_proxy("installed_apps", "app")
App.backups = association_proxy("installed_apps", "backup")
.
L'azione:
@blueprint.route("/backup/<int:backup_id>/apps.json")
def apps_json_for_backup(backup_id):
print "in apps_json_for_backup({})".format(backup_id)
backup = Backup.get_by_id(backup_id)
root = to_treemap(backup.apps)
return jsonify(root)
def to_treemap(apps):
root = {"name": "root", "children": list()}
genres = dict()
for app in apps:
if app.main_genre not in genres:
genres[app.main_genre] = list()
leaf = dict(name=app.name, size=app.full_size, compressed=app.compressed_size, bundle_id=app.bundle_id)
genres[app.main_genre].append(leaf)
for genre, leaves in genres.items():
root['children'].append(dict(name=genre, children=leaves))
return root
. Soluzione
OK, quindi ecco cosa è successo:
Quando ho fatto per la prima volta la tabella di backups_apps, non stavo usando crudmixin in modo che non abbia una colonna ID.Quando ho migrato la colonna ID, tutti i valori inizializzati a 0. SQLalchemy ignoravano tranquillamente tutte quelle righe multiple con lo stesso ID.