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devicehub-teal/ereuse_devicehub/resources/lot/models.py

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import uuid
from datetime import datetime
from flask import g
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy.orm import aliased
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from sqlalchemy.sql import expression
from sqlalchemy_utils import LtreeType
from sqlalchemy_utils.types.ltree import LQUERY
from teal.db import UUIDLtree
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from ereuse_devicehub.db import db
from ereuse_devicehub.resources.device.models import Device
from ereuse_devicehub.resources.models import STR_SIZE, Thing
from ereuse_devicehub.resources.user.models import User
class Lot(Thing):
id = db.Column(UUID(as_uuid=True), primary_key=True) # uuid is generated on init by default
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name = db.Column(db.Unicode(STR_SIZE), nullable=False)
closed = db.Column(db.Boolean, default=False, nullable=False)
closed.comment = """
A closed lot cannot be modified anymore.
"""
devices = db.relationship(Device,
backref=db.backref('parents', lazy=True, collection_class=set),
secondary=lambda: LotDevice.__table__,
collection_class=set)
"""
The **children** devices that the lot has.
Note that the lot can have more devices, if they are inside
descendant lots.
"""
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def __init__(self, name: str, closed: bool = closed.default.arg) -> None:
"""
Initializes a lot
:param name:
:param closed:
"""
super().__init__(id=uuid.uuid4(), name=name, closed=closed)
Path(self) # Lots have always one edge per default.
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def add_child(self, child):
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"""Adds a child to this lot."""
if isinstance(child, Lot):
Path.add(self.id, child.id)
db.session.refresh(self) # todo is this useful?
db.session.refresh(child)
else:
assert isinstance(child, uuid.UUID)
Path.add(self.id, child)
db.session.refresh(self) # todo is this useful?
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def remove_child(self, child: 'Lot'):
Path.delete(self.id, child.id)
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@property
def children(self):
"""The children lots."""
# From https://stackoverflow.com/a/41158890
# todo test
cls = self.__class__
exp = '*.{}.*{{1}}'.format(UUIDLtree.convert(self.id))
child_lots = aliased(Lot)
return self.query \
.join(cls.paths) \
.filter(Path.path.lquery(expression.cast(exp, LQUERY))) \
.join(child_lots, Path.lot)
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def __contains__(self, child: 'Lot'):
return Path.has_lot(self.id, child.id)
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@classmethod
def roots(cls):
"""Gets the lots that are not under any other lot."""
return set(cls.query.join(cls.paths).filter(db.func.nlevel(Path.path) == 1).all())
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def __repr__(self) -> str:
return '<Lot {0.name} devices={0.devices!r}>'.format(self)
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class LotDevice(db.Model):
device_id = db.Column(db.BigInteger, db.ForeignKey(Device.id), primary_key=True)
lot_id = db.Column(UUID(as_uuid=True), db.ForeignKey(Lot.id), primary_key=True)
created = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
author_id = db.Column(UUID(as_uuid=True),
db.ForeignKey(User.id),
nullable=False,
default=lambda: g.user.id)
author = db.relationship(User, primaryjoin=author_id == User.id)
author_id.comment = """
The user that put the device in the lot.
"""
class Path(db.Model):
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id = db.Column(db.UUID(as_uuid=True),
primary_key=True,
server_default=db.text('gen_random_uuid()'))
lot_id = db.Column(db.UUID(as_uuid=True), db.ForeignKey(Lot.id), nullable=False)
lot = db.relationship(Lot,
backref=db.backref('paths', lazy=True, collection_class=set),
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primaryjoin=Lot.id == lot_id)
path = db.Column(LtreeType, nullable=False)
created = db.Column(db.TIMESTAMP(timezone=True), server_default=db.text('CURRENT_TIMESTAMP'))
created.comment = """
When Devicehub created this.
"""
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__table_args__ = (
# dag.delete_edge needs to disable internally/temporarily the unique constraint
db.UniqueConstraint(path, name='path_unique', deferrable=True, initially='immediate'),
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db.Index('path_gist', path, postgresql_using='gist'),
db.Index('path_btree', path, postgresql_using='btree')
)
def __init__(self, lot: Lot) -> None:
super().__init__(lot=lot)
self.path = UUIDLtree(lot.id)
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@classmethod
def add(cls, parent_id: uuid.UUID, child_id: uuid.UUID):
"""Creates an edge between parent and child."""
db.session.execute(db.func.add_edge(str(parent_id), str(child_id)))
@classmethod
def delete(cls, parent_id: uuid.UUID, child_id: uuid.UUID):
"""Deletes the edge between parent and child."""
db.session.execute(db.func.delete_edge(str(parent_id), str(child_id)))
@classmethod
def has_lot(cls, parent_id: uuid.UUID, child_id: uuid.UUID) -> bool:
parent_id = UUIDLtree.convert(parent_id)
child_id = UUIDLtree.convert(child_id)
return bool(
db.session.execute(
"SELECT 1 from path where path ~ '*.{}.*.{}.*'".format(parent_id, child_id)
).first()
)