rename main code directory

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 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 '''
+    mediaType: str
+    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):
+        ''' 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):
+        ''' convert from an activity to a model '''
+        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 '''
+    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