moviewyrm/bookwyrm/activitypub/base_activity.py

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''' basics for an activitypub serializer '''
from dataclasses import dataclass, fields, MISSING
from json import JSONEncoder
from bookwyrm import books_manager, models
from django.db.models.fields.related_descriptors \
import ForwardManyToOneDescriptor
class ActivityEncoder(JSONEncoder):
''' used to convert an Activity object into json '''
def default(self, o):
return o.__dict__
@dataclass
class Image:
''' image block '''
url: str
type: str = 'Image'
@dataclass
class PublicKey:
''' public key block '''
id: str
owner: str
publicKeyPem: str
@dataclass
class Signature:
''' public key block '''
creator: str
created: str
signatureValue: str
type: str = 'RsaSignature2017'
@dataclass(init=False)
class ActivityObject:
''' actor activitypub json '''
id: str
type: str
def __init__(self, **kwargs):
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''' this lets you pass in an object with fields that aren't in the
dataclass, which it ignores. Any field in the dataclass is required or
has a default value '''
for field in fields(self):
try:
value = kwargs[field.name]
except KeyError:
if field.default == MISSING:
raise TypeError('Missing required field: %s' % field.name)
value = field.default
setattr(self, field.name, value)
def to_model(self, model, instance=None):
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''' convert from an activity to a model instance '''
if not isinstance(self, model.activity_serializer):
raise TypeError('Wrong activity type for model')
model_fields = [m.name for m in model._meta.get_fields()]
mapped_fields = {}
for mapping in model.activity_mappings:
if mapping.model_key not in model_fields:
continue
# value is None if there's a default that isn't supplied
# in the activity but is supplied in the formatter
value = None
if mapping.activity_key:
value = getattr(self, mapping.activity_key)
model_field = getattr(model, mapping.model_key)
# remote_id -> foreign key resolver
if isinstance(model_field, ForwardManyToOneDescriptor) and value:
fk_model = model_field.field.related_model
value = resolve_foreign_key(fk_model, value)
mapped_fields[mapping.model_key] = mapping.model_formatter(value)
# updating an existing model isntance
if instance:
for k, v in mapped_fields.items():
setattr(instance, k, v)
instance.save()
return instance
# creating a new model instance
return model.objects.create(**mapped_fields)
def serialize(self):
''' convert to dictionary with context attr '''
data = self.__dict__
data['@context'] = 'https://www.w3.org/ns/activitystreams'
return data
def resolve_foreign_key(model, remote_id):
''' look up the remote_id on an activity json field '''
if model in [models.Edition, models.Work]:
return books_manager.get_or_create_book(remote_id)
result = model.objects
if hasattr(model.objects, 'select_subclasses'):
result = result.select_subclasses()
result = result.filter(
remote_id=remote_id
).first()
if not result:
raise ValueError('Could not resolve remote_id in %s model: %s' % \
(model.__name__, remote_id))
return result