refactor: Improving default value handling

src/viur/core/bones/base.py

@@ -351,7 +351,7 @@ def isEmpty(self, value: t.Any) -> bool:
         """
         return not bool(value)
 
-    def getDefaultValue(self, skeletonInstance):
+    def getDefaultValue(self, skel: 'SkeletonInstance'):
         """
         Retrieves the default value for the bone.
 
@@ -361,14 +361,33 @@ def getDefaultValue(self, skeletonInstance):
 
         :return: The default value of the bone, which can be of any data type.
     """
+        def check_default_value(value):
+            # Accept list/tuple only when bone is multiple
+            if isinstance(value, (list, tuple)) and not self.multiple:
+                raise ValueError("Multiple default values not accepted")
+
+            return value
+
         if callable(self.defaultValue):
-            return self.defaultValue(skeletonInstance, self)
+            value = self.defaultValue(skel, self)
         elif isinstance(self.defaultValue, list):
-            return self.defaultValue[:]
+            value = self.defaultValue.copy()
         elif isinstance(self.defaultValue, dict):
-            return self.defaultValue.copy()
+            value = self.defaultValue.copy()
         else:
-            return self.defaultValue
+            value = self.defaultValue
+
+        # TODO: Handle languages...
+        # if self.languages:
+        #     if not isinstance(value, dict):
+        #         raise ValueError("Expected dict of languages")
+        #
+        #     if any(k not in self.languages for k in value):
+        #         raise ValueError("Language provided which is not in the languages setting")
+        #
+        #     return {k: check_default_value(v) for k, v in value.items()}
+
+        return check_default_value(value)
 
     def getEmptyValue(self) -> t.Any:
         """

src/viur/core/bones/relational.py

@@ -276,10 +276,7 @@ def __init__(
         self.consistency = consistency
 
         if getSystemInitialized():
-            from viur.core.skeleton import RefSkel, SkeletonInstance
-            self._refSkelCache = RefSkel.fromSkel(self.kind, *self.refKeys)
-            self._skeletonInstanceClassRef = SkeletonInstance
-            self._ref_keys = set(self._refSkelCache.__boneMap__.keys())
+            self.setSystemInitialized()
 
     def setSystemInitialized(self):
         """
@@ -296,9 +293,43 @@ def setSystemInitialized(self):
         self._refSkelCache = RefSkel.fromSkel(self.kind, *self.refKeys)
         self._skeletonInstanceClassRef = SkeletonInstance
         self._ref_keys = set(self._refSkelCache.__boneMap__.keys())
-    # from viur.core.skeleton import RefSkel, skeletonByKind
-    # self._refSkelCache = RefSkel.fromSkel(skeletonByKind(self.kind), *self.refKeys)
-    # self._usingSkelCache = self.using() if self.using else None
+
+    def getDefaultValue(self, skel: 'SkeletonInstance'):
+        """
+        Returns the default value of a RelationalBone.
+        Accepts that a default value can be
+        """
+        from viur.core.skeleton import SkeletonInstance
+
+        def rewrite_default_value(value):
+            # when there's no using skel, accept a directly provided key
+            if not self.using and isinstance(value, (db.Key, str, int)):
+                value = self.createRelSkelFromKey(value)
+
+            # this is awkward...
+            assert (
+                isinstance(value, dict)
+                and sorted(value.keys()) == ["dest", "rel"]
+                and isinstance(value["dest"], SkeletonInstance)
+                and value["dest"].kindName == self._refSkelCache.kindName
+                and (not self.using or isinstance(value["rel"], self.using))
+            )
+
+            return value
+
+        # first, obtain default value from super-call
+        value = super().getDefaultValue(skel)
+        if value is None:
+            return value
+
+        # handle list/tuple
+        if isinstance(value, (list, tuple)):
+            return [rewrite_default_value(val) for val in value]
+
+        # TODO: Handle languages.
+
+        # single value
+        return rewrite_default_value(value)
 
     def _getSkels(self):
         """

src/viur/core/session.py

@@ -203,6 +203,12 @@ def pop(self, key: str, default=_SENTINEL) -> t.Any:
 
         return default
 
+    def setdefault(self, key: str, value: t.Any) -> t.Any:
+        """
+            Set a default value in the current session
+        """
+        return self.session.setdefault(key, value)
+
 
 @tasks.CallDeferred
 def killSessionByUser(user: t.Optional[t.Union[str, "db.Key", None]] = None):