fix: Chroma - Fallback to default filter policy when deserializing …

…retrievers without the init parameter (#897)

* Add defensive check for filter_policy deserialization

* Add unit test

* Fix test

integrations/chroma/src/haystack_integrations/components/retrievers/chroma/retriever.py

@@ -100,7 +100,10 @@ def from_dict(cls, data: Dict[str, Any]) -> "ChromaQueryTextRetriever":
         """
         document_store = ChromaDocumentStore.from_dict(data["init_parameters"]["document_store"])
         data["init_parameters"]["document_store"] = document_store
-        data["init_parameters"]["filter_policy"] = FilterPolicy.from_str(data["init_parameters"]["filter_policy"])
+        # Pipelines serialized with old versions of the component might not
+        # have the filter_policy field.
+        if filter_policy := data["init_parameters"].get("filter_policy"):
+            data["init_parameters"]["filter_policy"] = FilterPolicy.from_str(filter_policy)
 
         return default_from_dict(cls, data)
 

integrations/chroma/tests/test_retriever.py

@@ -73,3 +73,32 @@ def test_retriever_from_json(request):
     assert retriever.filters == {"bar": "baz"}
     assert retriever.top_k == 42
     assert retriever.filter_policy == FilterPolicy.REPLACE
+
+
+@pytest.mark.integration
+def test_retriever_from_json_no_filter_policy(request):
+    data = {
+        "type": "haystack_integrations.components.retrievers.chroma.retriever.ChromaQueryTextRetriever",
+        "init_parameters": {
+            "filters": {"bar": "baz"},
+            "top_k": 42,
+            "document_store": {
+                "type": "haystack_integrations.document_stores.chroma.document_store.ChromaDocumentStore",
+                "init_parameters": {
+                    "collection_name": "test_retriever_from_json_no_filter_policy",
+                    "embedding_function": "HuggingFaceEmbeddingFunction",
+                    "persist_path": ".",
+                    "api_key": "1234567890",
+                    "distance_function": "l2",
+                },
+            },
+        },
+    }
+    retriever = ChromaQueryTextRetriever.from_dict(data)
+    assert retriever.document_store._collection_name == request.node.name
+    assert retriever.document_store._embedding_function == "HuggingFaceEmbeddingFunction"
+    assert retriever.document_store._embedding_function_params == {"api_key": "1234567890"}
+    assert retriever.document_store._persist_path == "."
+    assert retriever.filters == {"bar": "baz"}
+    assert retriever.top_k == 42
+    assert retriever.filter_policy == FilterPolicy.REPLACE  # default even if not specified