forked from mirrors/bookwyrm
317 lines
11 KiB
Python
317 lines
11 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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import logging
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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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logger = logging.getLogger(__name__)
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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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# pylint: disable=invalid-name
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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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def naive_parse(activity_objects, activity_json, serializer=None):
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"""this navigates circular import issues by looking up models' serializers"""
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if not serializer:
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if activity_json.get("publicKeyPem"):
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# ugh
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activity_json["type"] = "PublicKey"
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activity_type = activity_json.get("type")
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if activity_type in ["Question", "Article"]:
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return None
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try:
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serializer = activity_objects[activity_type]
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except KeyError as err:
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# we know this exists and that we can't handle it
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raise ActivitySerializerError(err)
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return serializer(activity_objects=activity_objects, **activity_json)
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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, activity_objects=None, **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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if value in (None, MISSING, {}):
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raise KeyError("Missing required field", field.name)
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try:
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is_subclass = issubclass(field.type, ActivityObject)
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except TypeError:
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is_subclass = False
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# serialize a model obj
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if hasattr(value, "to_activity"):
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value = value.to_activity()
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# parse a dict into the appropriate activity
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elif is_subclass and isinstance(value, dict):
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if activity_objects:
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value = naive_parse(activity_objects, value)
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else:
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value = naive_parse(
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activity_objects, value, serializer=field.type
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)
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except KeyError:
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if field.default == MISSING and field.default_factory == MISSING:
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raise ActivitySerializerError(
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f"Missing required field: {field.name}"
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)
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value = field.default
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setattr(self, field.name, value)
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# pylint: disable=too-many-locals,too-many-branches,too-many-arguments
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def to_model(
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self, model=None, instance=None, allow_create=True, save=True, overwrite=True
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):
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"""convert from an activity to a model instance"""
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model = model or get_model_from_type(self.type)
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# only reject statuses if we're potentially creating them
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if (
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allow_create
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and hasattr(model, "ignore_activity")
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and model.ignore_activity(self)
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):
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return None
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# check for an existing instance
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instance = instance or model.find_existing(self.serialize())
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if not instance and not allow_create:
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# so that we don't create when we want to delete or update
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return None
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instance = instance or model()
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# keep track of what we've changed
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update_fields = []
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# sets field on the model using the activity value
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for field in instance.simple_fields:
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try:
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changed = field.set_field_from_activity(
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instance, self, overwrite=overwrite
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)
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if changed:
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update_fields.append(field.name)
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except AttributeError as e:
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raise ActivitySerializerError(e)
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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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changed = field.set_field_from_activity(
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instance, self, save=save, overwrite=overwrite
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)
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if changed:
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update_fields.append(field.name)
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if not save:
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return instance
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with transaction.atomic():
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# can't force an update on fields unless the object already exists in the db
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if not instance.id:
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update_fields = None
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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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try:
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instance.save(broadcast=False, update_fields=update_fields)
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except TypeError:
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instance.save(update_fields=update_fields)
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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 (
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model_field_name,
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activity_field_name,
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) in 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, **kwargs):
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"""convert to dictionary with context attr"""
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omit = kwargs.get("omit", ())
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data = self.__dict__.copy()
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# recursively serialize
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for (k, v) in data.items():
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try:
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if issubclass(type(v), ActivityObject):
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data[k] = v.serialize()
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except TypeError:
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pass
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data = {k: v for (k, v) in data.items() if v is not None and k not in omit}
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if "@context" not in omit:
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data["@context"] = "https://www.w3.org/ns/activitystreams"
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return data
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@app.task(queue="medium_priority")
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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, related_remote_id, data
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):
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"""load reverse related fields (editions, attachments) without blocking"""
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model = apps.get_model(f"bookwyrm.{model_name}", require_ready=True)
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origin_model = apps.get_model(f"bookwyrm.{origin_model_name}", require_ready=True)
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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(f"Invalid related remote id: {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(activity, getattr(model_field, "activitypub_field"), instance.remote_id)
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item = activity.to_model(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 get_model_from_type(activity_type):
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"""given the activity, what type of model"""
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models = apps.get_models()
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model = [
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m
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for m in models
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if hasattr(m, "activity_serializer")
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and hasattr(m.activity_serializer, "type")
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and m.activity_serializer.type == activity_type
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]
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if not model:
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raise ActivitySerializerError(
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f'No model found for activity type "{activity_type}"'
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)
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return model[0]
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def resolve_remote_id(
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remote_id, model=None, refresh=False, save=True, get_activity=False
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):
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"""take a remote_id and return an instance, creating if necessary"""
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if model: # a bonus check we can do if we already know the model
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if isinstance(model, str):
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model = apps.get_model(f"bookwyrm.{model}", require_ready=True)
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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 if not get_activity else result.to_activity_dataclass()
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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:
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logger.exception("Could not connect to host for remote_id: %s", remote_id)
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return None
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# determine the model implicitly, if not provided
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# or if it's a model with subclasses like Status, check again
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if not model or hasattr(model.objects, "select_subclasses"):
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model = get_model_from_type(data.get("type"))
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# check for existing items with shared unique identifiers
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result = model.find_existing(data)
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if result and not refresh:
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return result if not get_activity else result.to_activity_dataclass()
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item = model.activity_serializer(**data)
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if get_activity:
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return item
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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=model, instance=result, save=save)
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@dataclass(init=False)
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class Link(ActivityObject):
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"""for tagging a book in a status"""
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href: str
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name: str = None
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mediaType: str = None
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id: str = None
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attributedTo: str = None
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availability: str = None
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type: str = "Link"
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def serialize(self, **kwargs):
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"""remove fields"""
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omit = ("id", "type", "@context")
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return super().serialize(omit=omit)
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@dataclass(init=False)
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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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