fix: ChromaDocumentStore - discard meta items when the type of th…

…eir value is not supported in Chroma (#907)

* discard invalid meta values

* reduce warnings

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

@@ -19,6 +19,7 @@
 
 
 VALID_DISTANCE_FUNCTIONS = "l2", "cosine", "ip"
+SUPPORTED_TYPES_FOR_METADATA_VALUES = str, int, float, bool
 
 
 class ChromaDocumentStore:
@@ -226,7 +227,26 @@ def write_documents(self, documents: List[Document], policy: DuplicatePolicy = D
             data = {"ids": [doc.id], "documents": [doc.content]}
 
             if doc.meta:
-                data["metadatas"] = [doc.meta]
+                valid_meta = {}
+                discarded_keys = []
+
+                for k, v in doc.meta.items():
+                    if isinstance(v, SUPPORTED_TYPES_FOR_METADATA_VALUES):
+                        valid_meta[k] = v
+                    else:
+                        discarded_keys.append(k)
+
+                if discarded_keys:
+                    logger.warning(
+                        "Document %s contains `meta` values of unsupported types for the keys: %s. "
+                        "These items will be discarded. Supported types are: %s.",
+                        doc.id,
+                        ", ".join(discarded_keys),
+                        ", ".join([t.__name__ for t in SUPPORTED_TYPES_FOR_METADATA_VALUES]),
+                    )
+
+                if valid_meta:
+                    data["metadatas"] = [valid_meta]
 
             if doc.embedding is not None:
                 data["embeddings"] = [doc.embedding]

integrations/chroma/tests/test_document_store.py

@@ -107,6 +107,28 @@ def test_search(self):
         assert len(result) == 1
         assert result[0][0].content == "Third document"
 
+    def test_write_documents_unsupported_meta_values(self, document_store: ChromaDocumentStore):
+        """
+        Unsupported meta values should be removed from the documents before writing them to the database
+        """
+
+        docs = [
+            Document(content="test doc 1", meta={"invalid": {"dict": "value"}}),
+            Document(content="test doc 2", meta={"invalid": ["list", "value"]}),
+            Document(content="test doc 3", meta={"ok": 123}),
+        ]
+
+        document_store.write_documents(docs)
+
+        written_docs = document_store.filter_documents()
+        written_docs.sort(key=lambda x: x.content)
+
+        assert len(written_docs) == 3
+        assert [doc.id for doc in written_docs] == [doc.id for doc in docs]
+        assert written_docs[0].meta == {}
+        assert written_docs[1].meta == {}
+        assert written_docs[2].meta == {"ok": 123}
+
     @pytest.mark.integration
     def test_to_json(self, request):
         ds = ChromaDocumentStore(