Fixes issue #5072 - adds additional support to Weaviate (#5085)

Implementation is similar to search_distance and where_filter

# adds 'additional' support to Weaviate queries

Co-authored-by: Dev 2049 <dev.dev2049@gmail.com>

langchain/vectorstores/weaviate.py

@@ -195,6 +195,8 @@ class Weaviate(VectorStore):
         query_obj = self._client.query.get(self._index_name, self._query_attrs)
         if kwargs.get("where_filter"):
             query_obj = query_obj.with_where(kwargs.get("where_filter"))
+        if kwargs.get("additional"):
+            query_obj = query_obj.with_additional(kwargs.get("additional"))
         result = query_obj.with_near_text(content).with_limit(k).do()
         if "errors" in result:
             raise ValueError(f"Error during query: {result['errors']}")
@@ -212,6 +214,8 @@ class Weaviate(VectorStore):
         query_obj = self._client.query.get(self._index_name, self._query_attrs)
         if kwargs.get("where_filter"):
             query_obj = query_obj.with_where(kwargs.get("where_filter"))
+        if kwargs.get("additional"):
+            query_obj = query_obj.with_additional(kwargs.get("additional"))
         result = query_obj.with_near_vector(vector).with_limit(k).do()
         if "errors" in result:
             raise ValueError(f"Error during query: {result['errors']}")

tests/integration_tests/vectorstores/test_weaviate.py

@@ -81,6 +81,28 @@ class TestWeaviate:
         )
         assert output == [Document(page_content="foo", metadata={"page": 0})]
 
+    @pytest.mark.vcr(ignore_localhost=True)
+    def test_similarity_search_with_metadata_and_additional(
+        self, weaviate_url: str, embedding_openai: OpenAIEmbeddings
+    ) -> None:
+        """Test end to end construction and search with metadata and additional."""
+        texts = ["foo", "bar", "baz"]
+        metadatas = [{"page": i} for i in range(len(texts))]
+        docsearch = Weaviate.from_texts(
+            texts, embedding_openai, metadatas=metadatas, weaviate_url=weaviate_url
+        )
+        output = docsearch.similarity_search(
+            "foo",
+            k=1,
+            additional=["certainty"],
+        )
+        assert output == [
+            Document(
+                page_content="foo",
+                metadata={"page": 0, "_additional": {"certainty": 1}},
+            )
+        ]
+
     @pytest.mark.vcr(ignore_localhost=True)
     def test_similarity_search_with_uuids(
         self, weaviate_url: str, embedding_openai: OpenAIEmbeddings