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