forked from mirrors/bookwyrm
206 lines
7 KiB
Python
206 lines
7 KiB
Python
''' basics for an activitypub serializer '''
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from dataclasses import dataclass, fields, MISSING
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from json import JSONEncoder
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from django.apps import apps
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from django.db import IntegrityError, transaction
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from bookwyrm.connectors import ConnectorException, get_data
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from bookwyrm.tasks import app
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class ActivitySerializerError(ValueError):
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''' routine problems serializing activitypub json '''
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class ActivityEncoder(JSONEncoder):
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''' used to convert an Activity object into json '''
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def default(self, o):
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return o.__dict__
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@dataclass
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class Link:
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''' for tagging a book in a status '''
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href: str
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name: str
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type: str = 'Link'
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@dataclass
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class Mention(Link):
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''' a subtype of Link for mentioning an actor '''
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type: str = 'Mention'
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@dataclass
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class Signature:
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''' public key block '''
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creator: str
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created: str
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signatureValue: str
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type: str = 'RsaSignature2017'
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@dataclass(init=False)
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class ActivityObject:
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''' actor activitypub json '''
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id: str
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type: str
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def __init__(self, **kwargs):
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''' this lets you pass in an object with fields that aren't in the
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dataclass, which it ignores. Any field in the dataclass is required or
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has a default value '''
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for field in fields(self):
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try:
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value = kwargs[field.name]
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except KeyError:
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if field.default == MISSING and \
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field.default_factory == MISSING:
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raise ActivitySerializerError(\
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'Missing required field: %s' % field.name)
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value = field.default
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setattr(self, field.name, value)
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def to_model(self, model, instance=None, save=True):
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''' convert from an activity to a model instance '''
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if not isinstance(self, model.activity_serializer):
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raise ActivitySerializerError(
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'Wrong activity type "%s" for model "%s" (expects "%s")' % \
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(self.__class__,
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model.__name__,
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model.activity_serializer)
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)
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if hasattr(model, 'ignore_activity') and model.ignore_activity(self):
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return instance
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# check for an existing instance, if we're not updating a known obj
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instance = instance or model.find_existing(self.serialize()) or model()
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for field in instance.simple_fields:
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field.set_field_from_activity(instance, self)
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# image fields have to be set after other fields because they can save
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# too early and jank up users
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for field in instance.image_fields:
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field.set_field_from_activity(instance, self, save=save)
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if not save:
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return instance
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with transaction.atomic():
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# we can't set many to many and reverse fields on an unsaved object
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try:
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instance.save()
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except IntegrityError as e:
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raise ActivitySerializerError(e)
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# add many to many fields, which have to be set post-save
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for field in instance.many_to_many_fields:
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# mention books/users, for example
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field.set_field_from_activity(instance, self)
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# reversed relationships in the models
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for (model_field_name, activity_field_name) in \
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instance.deserialize_reverse_fields:
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# attachments on Status, for example
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values = getattr(self, activity_field_name)
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if values is None or values is MISSING:
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continue
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model_field = getattr(model, model_field_name)
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# creating a Work, model_field is 'editions'
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# creating a User, model field is 'key_pair'
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related_model = model_field.field.model
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related_field_name = model_field.field.name
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for item in values:
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set_related_field.delay(
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related_model.__name__,
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instance.__class__.__name__,
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related_field_name,
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instance.remote_id,
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item
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)
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return instance
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def serialize(self):
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''' convert to dictionary with context attr '''
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data = self.__dict__
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data = {k:v for (k, v) in data.items() if v is not None}
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data['@context'] = 'https://www.w3.org/ns/activitystreams'
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return data
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@app.task
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@transaction.atomic
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def set_related_field(
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model_name, origin_model_name, related_field_name,
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related_remote_id, data):
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''' load reverse related fields (editions, attachments) without blocking '''
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model = apps.get_model('bookwyrm.%s' % model_name, require_ready=True)
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origin_model = apps.get_model(
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'bookwyrm.%s' % origin_model_name,
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require_ready=True
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)
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with transaction.atomic():
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if isinstance(data, str):
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existing = model.find_existing_by_remote_id(data)
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if existing:
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data = existing.to_activity()
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else:
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data = get_data(data)
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activity = model.activity_serializer(**data)
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# this must exist because it's the object that triggered this function
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instance = origin_model.find_existing_by_remote_id(related_remote_id)
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if not instance:
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raise ValueError(
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'Invalid related remote id: %s' % related_remote_id)
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# set the origin's remote id on the activity so it will be there when
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# the model instance is created
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# edition.parentWork = instance, for example
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model_field = getattr(model, related_field_name)
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if hasattr(model_field, 'activitypub_field'):
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setattr(
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activity,
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getattr(model_field, 'activitypub_field'),
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instance.remote_id
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)
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item = activity.to_model(model)
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# if the related field isn't serialized (attachments on Status), then
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# we have to set it post-creation
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if not hasattr(model_field, 'activitypub_field'):
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setattr(item, related_field_name, instance)
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item.save()
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def resolve_remote_id(model, remote_id, refresh=False, save=True):
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''' take a remote_id and return an instance, creating if necessary '''
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result = model.find_existing_by_remote_id(remote_id)
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if result and not refresh:
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return result
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# load the data and create the object
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try:
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data = get_data(remote_id)
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except (ConnectorException, ConnectionError):
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raise ActivitySerializerError(
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'Could not connect to host for remote_id in %s model: %s' % \
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(model.__name__, remote_id))
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# check for existing items with shared unique identifiers
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if not result:
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result = model.find_existing(data)
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if result and not refresh:
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return result
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item = model.activity_serializer(**data)
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# if we're refreshing, "result" will be set and we'll update it
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return item.to_model(model, instance=result, save=save)
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