Use MLClass when using the CreateClassifications helper

Closes #79 (closed)

arkindex_worker/worker/classification.py

@@ -4,6 +4,7 @@ ElementsWorker methods for classifications and ML classes.
 """
 
 from typing import Dict, List, Optional, Union
+from uuid import UUID
 
 from apistar.exceptions import ErrorResponse
 from peewee import IntegrityError
@@ -173,7+174,7 @@
                 return
 
             # Propagate any other API error
             raise
 
         self.report.add_classification(element.id, ml_class)
 
@@ -209,7+210,7 @@
                 ml_class_id, str
             ), f"Classification at index {index} in classifications: ml_class_id shouldn't be null and should be of type str"
 
+            # Make sure it's a valid UUID
+            try:
+                UUID(ml_class_id)
+            except ValueError:
+                raise ValueError(
+                    f"Classification at index {index} in classifications: ml_class_id is not a valid uuid."
+                )
+
             confidence = classification.get("confidence")
             assert (
                 confidence is not None