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

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import uuid
from datetime import datetime
from typing import Union
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from boltons import urlutils
from citext import CIText
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from flask import g
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from sqlalchemy import TEXT
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from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy_utils import LtreeType
from sqlalchemy_utils.types.ltree import LQUERY
from teal.db import CASCADE_OWN, UUIDLtree
from teal.resource import url_for_resource
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from ereuse_devicehub.db import create_view, db, exp, f
from ereuse_devicehub.resources.device.models import Component, Device
from ereuse_devicehub.resources.models import Thing
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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
name = db.Column(CIText(), nullable=False)
description = db.Column(CIText())
description.comment = """A comment about the lot."""
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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('lots', lazy=True, collection_class=set),
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secondary=lambda: LotDevice.__table__,
lazy=True,
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collection_class=set)
"""
The **children** devices that the lot has.
Note that the lot can have more devices, if they are inside
descendant lots.
"""
parents = db.relationship(lambda: Lot,
viewonly=True,
lazy=True,
collection_class=set,
secondary=lambda: LotParent.__table__,
primaryjoin=lambda: Lot.id == LotParent.child_id,
secondaryjoin=lambda: LotParent.parent_id == Lot.id,
cascade='refresh-expire', # propagate changes outside ORM
backref=db.backref('children',
viewonly=True,
lazy=True,
cascade='refresh-expire',
collection_class=set)
)
"""The parent lots."""
all_devices = db.relationship(Device,
viewonly=True,
lazy=True,
collection_class=set,
secondary=lambda: LotDeviceDescendants.__table__,
primaryjoin=lambda: Lot.id == LotDeviceDescendants.ancestor_lot_id,
secondaryjoin=lambda: LotDeviceDescendants.device_id == Device.id)
"""All devices, including components, inside this lot and its
descendants.
"""
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def __init__(self, name: str, closed: bool = closed.default.arg,
description: str = None) -> None:
"""
Initializes a lot
:param name:
:param closed:
"""
super().__init__(id=uuid.uuid4(), name=name, closed=closed, description=description)
Path(self) # Lots have always one edge per default.
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@property
def type(self) -> str:
return self.__class__.__name__
@property
def url(self) -> urlutils.URL:
"""The URL where to GET this action."""
return urlutils.URL(url_for_resource(Lot, item_id=self.id))
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@property
def descendants(self):
return self.descendantsq(self.id)
@classmethod
def descendantsq(cls, id):
_id = UUIDLtree.convert(id)
return (cls.id == Path.lot_id) & Path.path.lquery(exp.cast('*.{}.*'.format(_id), LQUERY))
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@classmethod
def roots(cls):
"""Gets the lots that are not under any other lot."""
return cls.query.join(cls.paths).filter(db.func.nlevel(Path.path) == 1)
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def add_children(self, *children):
"""Add children lots to this lot.
This operation is highly costly as it forces refreshing
many models in session.
"""
for child in children:
if isinstance(child, Lot):
Path.add(self.id, child.id)
db.session.refresh(child)
else:
assert isinstance(child, uuid.UUID)
Path.add(self.id, child)
# We need to refresh the models involved in this operation
# outside the session / ORM control so the models
# that have relationships to this model
# with the cascade 'refresh-expire' can welcome the changes
db.session.refresh(self)
def remove_children(self, *children):
"""Remove children lots from this lot.
This operation is highly costly as it forces refreshing
many models in session.
"""
for child in children:
if isinstance(child, Lot):
Path.delete(self.id, child.id)
db.session.refresh(child)
else:
assert isinstance(child, uuid.UUID)
Path.delete(self.id, child)
db.session.refresh(self)
def delete(self):
"""Deletes the lot.
This method removes the children lots and children
devices orphan from this lot and then marks this lot
for deletion.
"""
self.remove_children(*self.children)
db.session.delete(self)
def _refresh_models_with_relationships_to_lots(self):
session = db.Session.object_session(self)
for model in session:
if isinstance(model, (Device, Lot, Path)):
session.expire(model)
def __contains__(self, child: Union['Lot', Device]):
if isinstance(child, Lot):
return Path.has_lot(self.id, child.id)
elif isinstance(child, Device):
device = db.session.query(LotDeviceDescendants) \
.filter(LotDeviceDescendants.device_id == child.id) \
.filter(LotDeviceDescendants.ancestor_lot_id == self.id) \
.one_or_none()
return device
else:
raise TypeError('Lot only contains devices and lots, not {}'.format(child.__class__))
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)
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lot = db.relationship(Lot,
backref=db.backref('paths',
lazy=True,
collection_class=set,
cascade=CASCADE_OWN),
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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'),
db.Index('lot_id_index', lot_id, postgresql_using='hash')
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)
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()
)
class LotDeviceDescendants(db.Model):
"""A view facilitating querying inclusion between devices and lots,
including components.
The view has 4 columns:
1. The ID of the device.
2. The ID of a lot containing the device.
3. The ID of the lot that directly contains the device.
4. If 1. is a component, the ID of the device that is inside the lot.
"""
_ancestor = Lot.__table__.alias(name='ancestor')
"""Ancestor lot table."""
_desc = Lot.__table__.alias()
"""Descendant lot table."""
lot_device = _desc \
.join(LotDevice, _desc.c.id == LotDevice.lot_id) \
.join(Path, _desc.c.id == Path.lot_id)
"""Join: Path -- Lot -- LotDevice"""
descendants = "path.path ~ (CAST('*.'|| replace(CAST({}.id as text), '-', '_') " \
"|| '.*' AS LQUERY))".format(_ancestor.name)
"""Query that gets the descendants of the ancestor lot."""
devices = db.select([
LotDevice.device_id,
_desc.c.id.label('parent_lot_id'),
_ancestor.c.id.label('ancestor_lot_id'),
None
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]).select_from(_ancestor).select_from(lot_device).where(db.text(descendants))
# Components
_parent_device = Device.__table__.alias(name='parent_device')
"""The device that has the access to the lot."""
lot_device_component = lot_device \
.join(_parent_device, _parent_device.c.id == LotDevice.device_id) \
.join(Component, _parent_device.c.id == Component.parent_id)
"""Join: Path -- Lot -- LotDevice -- ParentDevice (Device) -- Component"""
components = db.select([
Component.id.label('device_id'),
_desc.c.id.label('parent_lot_id'),
_ancestor.c.id.label('ancestor_lot_id'),
LotDevice.device_id.label('device_parent_id'),
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]).select_from(_ancestor).select_from(lot_device_component).where(db.text(descendants))
__table__ = create_view('lot_device_descendants', devices.union(components))
class LotParent(db.Model):
i = f.index(Path.path, db.func.text2ltree(f.replace(exp.cast(Path.lot_id, TEXT), '-', '_')))
__table__ = create_view(
'lot_parent',
db.select([
Path.lot_id.label('child_id'),
exp.cast(f.replace(exp.cast(f.subltree(Path.path, i - 1, i), TEXT), '_', '-'),
UUID).label('parent_id')
]).select_from(Path).where(i > 0),
)