発散解像度 -divergence resolution-

Signed-off-by: Shin'ya Minazuki <shinyoukai@laidback.moe>

api/funkwhale_api/common/mutations.py

@@ -0,0 +1,171 @@
+import persisting_theory
+from django.db import models, transaction
+from rest_framework import serializers
+
+
+class ConfNotFound(KeyError):
+    pass
+
+
+class Registry(persisting_theory.Registry):
+    look_into = "mutations"
+
+    def connect(self, type, klass, perm_checkers=None):
+        def decorator(serializer_class):
+            t = self.setdefault(type, {})
+            t[klass] = {
+                "serializer_class": serializer_class,
+                "perm_checkers": perm_checkers or {},
+            }
+            return serializer_class
+
+        return decorator
+
+    @transaction.atomic
+    def apply(self, type, obj, payload):
+        conf = self.get_conf(type, obj)
+        serializer = conf["serializer_class"](obj, data=payload)
+        serializer.is_valid(raise_exception=True)
+        previous_state = serializer.get_previous_state(obj, serializer.validated_data)
+        serializer.apply(obj, serializer.validated_data)
+        return previous_state
+
+    def is_valid(self, type, obj, payload):
+        conf = self.get_conf(type, obj)
+        serializer = conf["serializer_class"](obj, data=payload)
+        return serializer.is_valid(raise_exception=True)
+
+    def get_validated_payload(self, type, obj, payload):
+        conf = self.get_conf(type, obj)
+        serializer = conf["serializer_class"](obj, data=payload)
+        serializer.is_valid(raise_exception=True)
+        return serializer.payload_serialize(serializer.validated_data)
+
+    def has_perm(self, perm, type, obj, actor):
+        if perm not in ["approve", "suggest"]:
+            raise ValueError(f"Invalid permission {perm}")
+        conf = self.get_conf(type, obj)
+        checker = conf["perm_checkers"].get(perm)
+        if not checker:
+            return False
+        return checker(obj=obj, actor=actor)
+
+    def get_conf(self, type, obj):
+        try:
+            type_conf = self[type]
+        except KeyError:
+            raise ConfNotFound(f"{type} is not a registered mutation")
+
+        try:
+            conf = type_conf[obj.__class__]
+        except KeyError:
+            try:
+                conf = type_conf[None]
+            except KeyError:
+                raise ConfNotFound(
+                    f"No mutation configuration found for {obj.__class__}"
+                )
+        return conf
+
+
+class MutationSerializer(serializers.Serializer):
+    def apply(self, obj, validated_data):
+        raise NotImplementedError()
+
+    def post_apply(self, obj, validated_data):
+        pass
+
+    def get_previous_state(self, obj, validated_data):
+        return
+
+    def payload_serialize(self, data):
+        return data
+
+
+class UpdateMutationSerializer(serializers.ModelSerializer, MutationSerializer):
+    def __init__(self, *args, **kwargs):
+        # we force partial mode, because update mutations are partial
+        kwargs.setdefault("partial", True)
+        super().__init__(*args, **kwargs)
+
+    @transaction.atomic
+    def apply(self, obj, validated_data):
+        r = self.update(obj, validated_data)
+        self.post_apply(r, validated_data)
+        return r
+
+    def validate(self, validated_data):
+        if not validated_data:
+            raise serializers.ValidationError("You must update at least one field")
+
+        return super().validate(validated_data)
+
+    def db_serialize(self, validated_data):
+        serialized_relations = self.get_serialized_relations()
+        data = {}
+        # ensure model fields are serialized properly
+        for key, value in list(validated_data.items()):
+            if not isinstance(value, models.Model):
+                data[key] = value
+                continue
+            field = serialized_relations[key]
+            data[key] = getattr(value, field)
+        return data
+
+    def payload_serialize(self, data):
+        data = super().payload_serialize(data)
+        # we use our serialized_relations configuration
+        # to ensure we store ids instead of model instances in our json
+        # payload
+        for field, attr in self.get_serialized_relations().items():
+            try:
+                obj = data[field]
+            except KeyError:
+                continue
+            if obj is None:
+                data[field] = None
+            else:
+                data[field] = getattr(obj, attr)
+        return data
+
+    def create(self, validated_data):
+        validated_data = self.db_serialize(validated_data)
+        return super().create(validated_data)
+
+    def get_previous_state(self, obj, validated_data):
+        return get_update_previous_state(
+            obj,
+            *list(validated_data.keys()),
+            serialized_relations=self.get_serialized_relations(),
+            handlers=self.get_previous_state_handlers(),
+        )
+
+    def get_serialized_relations(self):
+        return {}
+
+    def get_previous_state_handlers(self):
+        return {}
+
+
+def get_update_previous_state(obj, *fields, serialized_relations={}, handlers={}):
+    if not fields:
+        raise ValueError("You need to provide at least one field")
+
+    state = {}
+    for field in fields:
+        if field in handlers:
+            state[field] = handlers[field](obj)
+            continue
+        value = getattr(obj, field)
+        if isinstance(value, models.Model):
+            # we store the related object id and repr for better UX
+            id_field = serialized_relations[field]
+            related_value = getattr(value, id_field)
+            state[field] = {"value": related_value, "repr": str(value)}
+        else:
+            state[field] = {"value": value}
+
+    return state
+
+
+registry = Registry()