Check explicitly for modelType in Python (#509)

We add an explicit check for missing ``modelType`` in generated Python
code to account for the case where a concrete class without descendants
needs a model type for backwards compatibility even though the model
type property is redundant.

aas_core_codegen/python/jsonization/_generate.py

@@ -706,6 +706,26 @@ def _generate_concrete_class_from_jsonable(
         Stripped(f"setter = {setter_cls_name}()"),
     ]  # type: List[Stripped]
 
+    # NOTE (mristin):
+    # If the class has no concrete descendants, this function will be the sole entry
+    # point for the de-serialization. In that case, we have to explicitly check if
+    # the ``modelType`` is present — for cases where the serialization rules impose
+    # a model type for backwards compatibility even though it is redundant.
+    #
+    # If the class has concrete descendants, we can only publicly de-serialize it
+    # through a dispatching function, which will innately check for model type, so we
+    # do not have to repeat the check here.
+    if len(cls.concrete_descendants) == 0 and cls.serialization.with_model_type:
+        blocks.append(
+            Stripped(
+                f"""\
+if 'modelType' not in jsonable:
+{I}raise DeserializationException(
+{II}"Expected the property modelType, but found none"
+{I})"""
+            )
+        )
+
     # region Switch on property name
 
     map_name = python_naming.private_constant_name(
@@ -793,7 +813,7 @@ def _generate_concrete_class_from_jsonable(
 
     writer = io.StringIO()
 
-    if len(cls._concrete_descendants) == 0:
+    if len(cls.concrete_descendants) == 0:
         function_name = python_naming.function_name(
             Identifier(f"{cls.name}_from_jsonable")
         )

test_data/python/test_main/aas_core_meta.v3/expected_output/jsonization.py

@@ -1443,6 +1443,11 @@ def asset_administration_shell_from_jsonable(
 
     setter = _SetterForAssetAdministrationShell()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_ASSET_ADMINISTRATION_SHELL.get(key)
@@ -2291,6 +2296,11 @@ def submodel_from_jsonable(
 
     setter = _SetterForSubmodel()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_SUBMODEL.get(key)
@@ -3190,6 +3200,11 @@ def submodel_element_list_from_jsonable(
 
     setter = _SetterForSubmodelElementList()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_SUBMODEL_ELEMENT_LIST.get(key)
@@ -3563,6 +3578,11 @@ def submodel_element_collection_from_jsonable(
 
     setter = _SetterForSubmodelElementCollection()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_SUBMODEL_ELEMENT_COLLECTION.get(key)
@@ -3968,6 +3988,11 @@ def property_from_jsonable(
 
     setter = _SetterForProperty()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_PROPERTY.get(key)
@@ -4353,6 +4378,11 @@ def multi_language_property_from_jsonable(
 
     setter = _SetterForMultiLanguageProperty()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_MULTI_LANGUAGE_PROPERTY.get(key)
@@ -4723,6 +4753,11 @@ def range_from_jsonable(
 
     setter = _SetterForRange()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_RANGE.get(key)
@@ -5071,6 +5106,11 @@ def reference_element_from_jsonable(
 
     setter = _SetterForReferenceElement()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_REFERENCE_ELEMENT.get(key)
@@ -5426,6 +5466,11 @@ def blob_from_jsonable(
 
     setter = _SetterForBlob()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_BLOB.get(key)
@@ -5787,6 +5832,11 @@ def file_from_jsonable(
 
     setter = _SetterForFile()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_FILE.get(key)
@@ -6185,6 +6235,11 @@ def annotated_relationship_element_from_jsonable(
 
     setter = _SetterForAnnotatedRelationshipElement()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_ANNOTATED_RELATIONSHIP_ELEMENT.get(key)
@@ -6626,6 +6681,11 @@ def entity_from_jsonable(
 
     setter = _SetterForEntity()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_ENTITY.get(key)
@@ -7375,6 +7435,11 @@ def basic_event_element_from_jsonable(
 
     setter = _SetterForBasicEventElement()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_BASIC_EVENT_ELEMENT.get(key)
@@ -7835,6 +7900,11 @@ def operation_from_jsonable(
 
     setter = _SetterForOperation()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_OPERATION.get(key)
@@ -8237,6 +8307,11 @@ def capability_from_jsonable(
 
     setter = _SetterForCapability()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_CAPABILITY.get(key)
@@ -8540,6 +8615,11 @@ def concept_description_from_jsonable(
 
     setter = _SetterForConceptDescription()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_CONCEPT_DESCRIPTION.get(key)
@@ -10286,6 +10366,11 @@ def data_specification_iec_61360_from_jsonable(
 
     setter = _SetterForDataSpecificationIEC61360()
 
+    if 'modelType' not in jsonable:
+        raise DeserializationException(
+            "Expected the property modelType, but found none"
+        )
+
     for key, jsonable_value in jsonable.items():
         setter_method = (
             _SETTER_MAP_FOR_DATA_SPECIFICATION_IEC_61360.get(key)