Resolve "Screening for signups"

api/funkwhale_api/common/preferences.py

@@ -1,4 +1,7 @@
+import json
+
 from django import forms
+from django.contrib.postgres.forms import JSONField
 from django.conf import settings
 from dynamic_preferences import serializers, types
 from dynamic_preferences.registries import global_preferences_registry
@@ -57,3 +60,48 @@ class StringListPreference(types.BasePreferenceType):
         d = super(StringListPreference, self).get_api_additional_data()
         d["choices"] = self.get("choices")
         return d
+
+
+class JSONSerializer(serializers.BaseSerializer):
+    required = True
+
+    @classmethod
+    def to_db(cls, value, **kwargs):
+        if not cls.required and value is None:
+            return json.dumps(value)
+        data_serializer = cls.data_serializer_class(data=value)
+        if not data_serializer.is_valid():
+            raise cls.exception(
+                "{} is not a valid value: {}".format(value, data_serializer.errors)
+            )
+        value = data_serializer.validated_data
+        try:
+            return json.dumps(value, sort_keys=True)
+        except TypeError:
+            raise cls.exception(
+                "Cannot serialize, value {} is not JSON serializable".format(value)
+            )
+
+    @classmethod
+    def to_python(cls, value, **kwargs):
+        return json.loads(value)
+
+
+class SerializedPreference(types.BasePreferenceType):
+    """
+    A preference that store arbitrary JSON and validate it using a rest_framework
+    serializer
+    """
+
+    serializer = JSONSerializer
+    data_serializer_class = None
+    field_class = JSONField
+    widget = forms.Textarea
+
+    @property
+    def serializer(self):
+        class _internal(JSONSerializer):
+            data_serializer_class = self.data_serializer_class
+            required = self.get("required")
+
+        return _internal