Support existing identical classifications.

arkindex_worker/worker.py

@@ -350,16 +350,34 @@ class ElementsWorker(BaseWorker):
             )
             return
 
-        self.api_client.request(
-            "CreateClassification",
-            body={
-                "element": element.id,
-                "ml_class": self.get_ml_class_id(element.corpus.id, ml_class),
-                "worker_version": self.worker_version_id,
-                "confidence": confidence,
-                "high_confidence": high_confidence,
-            },
-        )
+        try:
+            self.api_client.request(
+                "CreateClassification",
+                body={
+                    "element": element.id,
+                    "ml_class": self.get_ml_class_id(element.corpus.id, ml_class),
+                    "worker_version": self.worker_version_id,
+                    "confidence": confidence,
+                    "high_confidence": high_confidence,
+                },
+            )
+        except ErrorResponse as e:
+
+            # Detect already existing classification
+            if (
+                e.status_code == 400
+                and "non_field_errors" in e.content
+                and "The fields element, worker_version, ml_class must make a unique set."
+                in e.content["non_field_errors"]
+            ):
+                logger.warning(
+                    f"This worker version has already set {ml_class} on element {element.id}"
+                )
+                return
+
+            # Propagate any other API error
+            raise
+
         self.report.add_classification(element.id, ml_class)
 
     def create_entity(self, element, name, type, corpus, metas=None, validated=None):

tests/test_elements_worker.py

@@ -991,6 +991,57 @@ def test_create_classification(responses, mock_elements_worker):
         "high_confidence": True,
     }
 
+    # Classification has been created and reported
+    assert mock_elements_worker.report.report_data["elements"][elt.id][
+        "classifications"
+    ] == {"a_class": 1}
+
+
+def test_create_classification_duplicate(responses, mock_elements_worker):
+    mock_elements_worker.classes = {
+        "11111111-1111-1111-1111-111111111111": {"a_class": "0000"}
+    }
+    elt = Element(
+        {
+            "id": "12341234-1234-1234-1234-123412341234",
+            "corpus": {"id": "11111111-1111-1111-1111-111111111111"},
+        }
+    )
+    responses.add(
+        responses.POST,
+        "http://testserver/api/v1/classifications/",
+        status=400,
+        json={
+            "non_field_errors": [
+                "The fields element, worker_version, ml_class must make a unique set."
+            ]
+        },
+    )
+
+    mock_elements_worker.create_classification(
+        element=elt,
+        ml_class="a_class",
+        confidence=0.42,
+        high_confidence=True,
+    )
+
+    assert len(responses.calls) == 2
+    assert [call.request.url for call in responses.calls] == [
+        "http://testserver/api/v1/workers/versions/12341234-1234-1234-1234-123412341234/",
+        "http://testserver/api/v1/classifications/",
+    ]
+
+    assert json.loads(responses.calls[1].request.body) == {
+        "element": "12341234-1234-1234-1234-123412341234",
+        "ml_class": "0000",
+        "worker_version": "12341234-1234-1234-1234-123412341234",
+        "confidence": 0.42,
+        "high_confidence": True,
+    }
+
+    # Classification has NOT been created
+    assert mock_elements_worker.report.report_data["elements"] == {}
+
 
 def test_create_entity_wrong_element(mock_elements_worker):
     with pytest.raises(AssertionError) as e: