Fix tag being undefined bug from the backend.

package/kedro_viz/data_access/repositories/graph.py

@@ -12,11 +12,12 @@ def __init__(self):
         self.nodes_dict: Dict[str, GraphNode] = {}
         self.nodes_list: List[GraphNode] = []
 
-    def has_node(self, node: GraphNode) -> bool:
-        return node.id in self.nodes_dict
-
     def add_node(self, node: GraphNode) -> GraphNode:
-        if not self.has_node(node):
+        existing_node = self.nodes_dict.get(node.id)
+        if existing_node:
+            # Update tags or other attributes if the node already exists
+            existing_node.tags.update(node.tags)
+        else:
             self.nodes_dict[node.id] = node
             self.nodes_list.append(node)
         return self.nodes_dict[node.id]

package/tests/conftest.py

@@ -222,6 +222,7 @@ def example_pipeline_with_node_namespaces():
                 inputs=["raw_transaction_data", "cleaned_transaction_data"],
                 outputs="validated_transaction_data",
                 name="validation_node",
+                tags=["validation"],
             ),
             node(
                 func=lambda validated_data, enrichment_data: (
@@ -381,6 +382,23 @@ def edge_case_example_pipelines(
     }
 
 
+@pytest.fixture
+def example_pipelines_with_additional_tags(example_pipeline_with_node_namespaces):
+    """
+    Fixture to mock the use cases mentioned in
+    https://github.com/kedro-org/kedro-viz/issues/2106
+    """
+
+    pipelines_dict = {
+        "pipeline": example_pipeline_with_node_namespaces,
+        "pipeline_with_tags": pipeline(
+            example_pipeline_with_node_namespaces, tags=["tag1", "tag2"]
+        ),
+    }
+
+    yield pipelines_dict
+
+
 @pytest.fixture
 def expected_modular_pipeline_tree_for_edge_cases():
     expected_tree_for_edge_cases_file_path = (
@@ -554,6 +572,41 @@ def example_api_for_edge_case_pipelines(
     yield api
 
 
+@pytest.fixture
+def example_api_for_pipelines_with_additional_tags(
+    data_access_manager: DataAccessManager,
+    example_pipelines_with_additional_tags: Dict[str, Pipeline],
+    example_catalog: DataCatalog,
+    session_store: BaseSessionStore,
+    mocker,
+):
+    api = apps.create_api_app_from_project(mock.MagicMock())
+
+    # For readability we are not hashing the node id
+    mocker.patch("kedro_viz.utils._hash", side_effect=lambda value: value)
+    mocker.patch(
+        "kedro_viz.data_access.repositories.modular_pipelines._hash",
+        side_effect=lambda value: value,
+    )
+
+    populate_data(
+        data_access_manager,
+        example_catalog,
+        example_pipelines_with_additional_tags,
+        session_store,
+        {},
+    )
+    mocker.patch(
+        "kedro_viz.api.rest.responses.pipelines.data_access_manager",
+        new=data_access_manager,
+    )
+    mocker.patch(
+        "kedro_viz.api.rest.responses.nodes.data_access_manager",
+        new=data_access_manager,
+    )
+    yield api
+
+
 @pytest.fixture
 def example_transcoded_api(
     data_access_manager: DataAccessManager,

package/tests/test_api/test_rest/test_responses/test_pipelines.py

@@ -35,6 +35,20 @@ def test_endpoint_main_no_default_pipeline(self, example_api_no_default_pipeline
             {"id": "data_processing", "name": "data_processing"},
         ]
 
+    def test_endpoint_main_for_pipelines_with_additional_tags(
+        self,
+        example_api_for_pipelines_with_additional_tags,
+    ):
+        expected_tags = [
+            {"id": "tag1", "name": "tag1"},
+            {"id": "tag2", "name": "tag2"},
+            {"id": "validation", "name": "validation"},
+        ]
+        client = TestClient(example_api_for_pipelines_with_additional_tags)
+        response = client.get("/api/main")
+        actual_tags = response.json()["tags"]
+        assert actual_tags == expected_tags
+
     def test_endpoint_main_for_edge_case_pipelines(
         self,
         example_api_for_edge_case_pipelines,