langchain: Add aadd_documents to ParentDocumentRetriever (#23969)

- **Description:** Add an async version of `add_documents` to
`ParentDocumentRetriever`
-  **Twitter handle:** @johnkdev

---------

Co-authored-by: John Kelly <j.kelly@mwam.com>
Co-authored-by: Chester Curme <chester.curme@gmail.com>
Co-authored-by: Eugene Yurtsev <eyurtsev@gmail.com>

libs/langchain/langchain/retrievers/parent_document_retriever.py

@@ -1,5 +1,5 @@
 import uuid
-from typing import Any, List, Optional, Sequence
+from typing import Any, List, Optional, Sequence, Tuple
 
 from langchain_core.documents import Document
 from langchain_text_splitters import TextSplitter
@@ -69,27 +69,12 @@ class ParentDocumentRetriever(MultiVectorRetriever):
         metadata.
     """
 
-    def add_documents(
+    def _split_docs_for_adding(
         self,
         documents: List[Document],
         ids: Optional[List[str]] = None,
         add_to_docstore: bool = True,
-        **kwargs: Any,
+    ) -> Tuple[List[Document], List[Tuple[str, Document]]]:
-    ) -> None:
-        """Adds documents to the docstore and vectorstores.
-
-        Args:
-            documents: List of documents to add
-            ids: Optional list of ids for documents. If provided should be the same
-                length as the list of documents. Can be provided if parent documents
-                are already in the document store and you don't want to re-add
-                to the docstore. If not provided, random UUIDs will be used as
-                ids.
-            add_to_docstore: Boolean of whether to add documents to docstore.
-                This can be false if and only if `ids` are provided. You may want
-                to set this to False if the documents are already in the docstore
-                and you don't want to re-add them.
-        """
         if self.parent_splitter is not None:
             documents = self.parent_splitter.split_documents(documents)
         if ids is None:
@@ -120,6 +105,43 @@ class ParentDocumentRetriever(MultiVectorRetriever):
                 _doc.metadata[self.id_key] = _id
             docs.extend(sub_docs)
             full_docs.append((_id, doc))
+
+        return docs, full_docs
+
+    def add_documents(
+        self,
+        documents: List[Document],
+        ids: Optional[List[str]] = None,
+        add_to_docstore: bool = True,
+        **kwargs: Any,
+    ) -> None:
+        """Adds documents to the docstore and vectorstores.
+
+        Args:
+            documents: List of documents to add
+            ids: Optional list of ids for documents. If provided should be the same
+                length as the list of documents. Can be provided if parent documents
+                are already in the document store and you don't want to re-add
+                to the docstore. If not provided, random UUIDs will be used as
+                ids.
+            add_to_docstore: Boolean of whether to add documents to docstore.
+                This can be false if and only if `ids` are provided. You may want
+                to set this to False if the documents are already in the docstore
+                and you don't want to re-add them.
+        """
+        docs, full_docs = self._split_docs_for_adding(documents, ids, add_to_docstore)
         self.vectorstore.add_documents(docs, **kwargs)
         if add_to_docstore:
             self.docstore.mset(full_docs)
+
+    async def aadd_documents(
+        self,
+        documents: List[Document],
+        ids: Optional[List[str]] = None,
+        add_to_docstore: bool = True,
+        **kwargs: Any,
+    ) -> None:
+        docs, full_docs = self._split_docs_for_adding(documents, ids, add_to_docstore)
+        await self.vectorstore.aadd_documents(docs, **kwargs)
+        if add_to_docstore:
+            await self.docstore.amset(full_docs)