fix: Allow search in ChromaDocumentStore without metadata

integrations/chroma/src/haystack_integrations/document_stores/chroma/document_store.py

@@ -428,8 +428,12 @@ def _query_result_to_documents(result: QueryResult) -> List[List[Document]]:
                 }
 
                 # prepare metadata
-                if metadatas := result.get("metadatas"):
-                    document_dict["meta"] = dict(metadatas[i][j])
+                metadatas = result.get("metadatas")
+                try:
+                    if metadatas and metadatas[i][j] is not None:
+                        document_dict["meta"] = metadatas[i][j]
+                except IndexError:
+                    pass
 
                 if embeddings := result.get("embeddings"):
                     document_dict["embedding"] = np.array(embeddings[i][j])

integrations/chroma/tests/test_document_store.py

@@ -92,6 +92,21 @@ def test_delete_not_empty_nonexisting(self, document_store: ChromaDocumentStore)
 
         assert document_store.filter_documents(filters={"id": doc.id}) == [doc]
 
+    def test_search(self):
+        document_store = ChromaDocumentStore()
+        documents = [
+            Document(content="First document", meta={"author": "Author1"}),
+            Document(content="Second document"),  # No metadata
+            Document(content="Third document", meta={"author": "Author2"}),
+            Document(content="Fourth document"),  # No metadata
+        ]
+        document_store.write_documents(documents)
+        result = document_store.search(["Third"], top_k=1)
+
+        # Assertions to verify correctness
+        assert len(result) == 1
+        assert result[0][0].content == "Third document"
+
     @pytest.mark.integration
     def test_to_json(self, request):
         ds = ChromaDocumentStore(