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devicehub-teal/ereuse_devicehub/resources/device/sync.py

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from contextlib import suppress
from itertools import groupby
from typing import Iterable, Set
from sqlalchemy import inspect
from sqlalchemy.exc import IntegrityError
from sqlalchemy.util import OrderedSet
from teal.db import ResourceNotFound
from teal.marshmallow import ValidationError
from ereuse_devicehub.db import db
from ereuse_devicehub.resources.device.exceptions import NeedsId
from ereuse_devicehub.resources.device.models import Component, Computer, Device
from ereuse_devicehub.resources.event.models import Remove
from ereuse_devicehub.resources.tag.model import Tag
class Sync:
"""Synchronizes the device and components with the database."""
def run(self,
device: Device,
components: Iterable[Component] or None) -> (Device, OrderedSet):
"""
Synchronizes the device and components with the database.
Identifies if the device and components exist in the database
and updates / inserts them as necessary.
Passed-in parameters have to be transient, or said differently,
not-db-synced objects, or otherwise they would end-up being
added in the session. `Learn more... <http://docs.sqlalchemy.org/
en/latest/orm/session_state_management.html#quickie-intro-to
-object-states>`_.
This performs Add / Remove as necessary.
:param device: The device to add / update to the database.
:param components: Components that are inside of the device.
This method performs Add and Remove events
so the device ends up with these components.
Components are added / updated accordingly.
If this is empty, all components are removed.
If this is None, it means that we are not
providing info about the components, in which
case we keep the already existing components
of the device we don't touch them.
:return: A tuple of:
1. The device from the database (with an ID) whose
``components`` field contain the db version
of the passed-in components.
2. A list of Add / Remove (not yet added to session).
"""
db_device = self.execute_register(device)
db_components, events = OrderedSet(), OrderedSet()
if components is not None: # We have component info (see above)
assert isinstance(db_device, Computer)
blacklist = set() # type: Set[int]
not_new_components = set()
for component in components:
db_component, is_new = self.execute_register_component(component,
blacklist,
parent=db_device)
db_components.add(db_component)
if not is_new:
not_new_components.add(db_component)
# We only want to perform Add/Remove to not new components
events = self.add_remove(db_device, not_new_components)
db_device.components = db_components
return db_device, events
def execute_register_component(self,
component: Component,
blacklist: Set[int],
parent: Computer):
"""
Synchronizes one component to the DB.
This method is a specialization of :meth:`.execute_register`
but for components that are inside parents.
This method assumes components don't have tags, and it tries
to identify a non-hid component by finding a
:meth:`ereuse_devicehub.resources.device.models.Component.
similar_one`.
:param component: The component to sync.
:param blacklist: A set of components already found by
Component.similar_one(). Pass-in an empty Set.
:param parent: For components, the computer that contains them.
Helper used by Component.similar_one().
:return: A tuple with:
- The synced component. See :meth:`.execute_register`
for more info.
- A flag stating if the device is new or it already
existed in the DB.
"""
assert inspect(component).transient, 'Component should not be synced from DB'
try:
if component.hid:
db_component = Device.query.filter_by(hid=component.hid).one()
else:
# Is there a component similar to ours?
db_component = component.similar_one(parent, blacklist)
# We blacklist this component so we
# ensure we don't get it again for another component
# with the same physical properties
blacklist.add(db_component.id)
except ResourceNotFound:
db.session.add(component)
# db.session.flush()
db_component = component
is_new = True
else:
self.merge(component, db_component)
is_new = False
return db_component, is_new
def execute_register(self, device: Device) -> Device:
"""
Synchronizes one device to the DB.
This method tries to get an existing device using the HID
or one of the tags, and...
- if it already exists it returns a "local synced version"
the same ``device`` you passed-in but with updated values
from the database. In this case we do not
"touch" any of its values on the DB.
- If it did not exist, a new device is created in the db.
This method validates that all passed-in tags (``device.tags``),
if linked, are linked to the same device, ditto for the hid.
Finally it links the tags with the device.
If you pass-in a component that is inside a parent, use
:meth:`.execute_register_component` as it has more specialized
methods to handle them.
:param device: The device to synchronize to the DB.
:raise NeedsId: The device has not any identifier we can use.
To still create the device use
``force_creation``.
:raise DatabaseError: Any other error from the DB.
:return: The synced device from the db with the tags linked.
"""
assert inspect(device).transient, 'Device cannot be already synced from DB'
assert all(inspect(tag).transient for tag in device.tags), 'Tags cannot be synced from DB'
if not device.tags and not device.hid:
# We cannot identify this device
raise NeedsId()
db_device = None
if device.hid:
with suppress(ResourceNotFound):
db_device = Device.query.filter_by(hid=device.hid).one()
try:
tags = {Tag.from_an_id(tag.id).one() for tag in device.tags} # type: Set[Tag]
except ResourceNotFound:
raise ResourceNotFound('tag you are linking to device {}'.format(device))
linked_tags = {tag for tag in tags if tag.device_id} # type: Set[Tag]
if linked_tags:
sample_tag = next(iter(linked_tags))
for tag in linked_tags:
if tag.device_id != sample_tag.device_id:
raise MismatchBetweenTags(tag, sample_tag) # Linked to different devices
if db_device: # Device from hid
if sample_tag.device_id != db_device.id: # Device from hid != device from tags
raise MismatchBetweenTagsAndHid(db_device.id, db_device.hid)
else: # There was no device from hid
db_device = sample_tag.device
if db_device: # Device from hid or tags
self.merge(device, db_device)
else: # Device is new and tags are not linked to a device
device.tags.clear() # We don't want to add the transient dummy tags
db.session.add(device)
db_device = device
db_device.tags |= tags # Union of tags the device had plus the (potentially) new ones
try:
db.session.flush()
except IntegrityError as e:
# Manage 'one tag per organization' unique constraint
if 'One tag per organization' in e.args[0]:
# todo test for this
id = int(e.args[0][135:e.args[0].index(',', 135)])
raise ValidationError('The device is already linked to tag {} '
'from the same organization.'.format(id),
field_names=['device.tags'])
else:
raise
assert db_device is not None
return db_device
@staticmethod
def merge(device: Device, db_device: Device):
"""
Copies the physical properties of the device to the db_device.
This method mutates db_device.
"""
for field_name, value in device.physical_properties.items():
if value is not None:
setattr(db_device, field_name, value)
@staticmethod
def add_remove(device: Computer,
components: Set[Component]) -> OrderedSet:
"""
Generates the Add and Remove events (but doesn't add them to
session).
:param device: A device which ``components`` attribute contains
the old list of components. The components that
are not in ``components`` will be Removed.
:param components: List of components that are potentially to
be Added. Some of them can already exist
on the device, in which case they won't
be re-added.
:return: A list of Add / Remove events.
"""
# Note that we create the Remove events before the Add ones
events = OrderedSet()
old_components = set(device.components)
adding = components - old_components
if adding:
# For the components we are adding, let's remove them from their old parents
def g_parent(component: Component) -> Device:
return component.parent or Computer(id=0) # Computer with id 0 is our Identity
for parent, _components in groupby(sorted(adding, key=g_parent), key=g_parent):
if parent.id != 0: # Is not Computer Identity
events.add(Remove(device=parent, components=OrderedSet(_components)))
return events
class MismatchBetweenTags(ValidationError):
def __init__(self,
tag: Tag,
other_tag: Tag,
field_names={'device.tags'}):
message = '{!r} and {!r} are linked to different devices.'.format(tag, other_tag)
super().__init__(message, field_names)
class MismatchBetweenTagsAndHid(ValidationError):
def __init__(self,
device_id: int,
hid: str,
field_names={'device.hid'}):
message = 'Tags are linked to device {} but hid refers to device {}.'.format(device_id,
hid)
super().__init__(message, field_names)