docs: Message history for Neptune chains (#29260)

Expanded the Amazon Neptune documentation with new sections detailing
usage of chat message history with the
`create_neptune_opencypher_qa_chain` and
`create_neptune_sparql_qa_chain` functions.

Author: michaelnchin

docs/docs/integrations/graphs/amazon_neptune_open_cypher.ipynb

@@ -70,9 +70,17 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 12,
    "metadata": {},
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Austin airport has 98 outgoing routes.\n"
+     ]
+    }
+   ],
    "source": [
     "from langchain_aws import ChatBedrockConverse\n",
     "from langchain_aws.chains import create_neptune_opencypher_qa_chain\n",
@@ -83,21 +91,169 @@
     "    temperature=0,\n",
     ")\n",
     "\n",
-    "chain = create_neptune_opencypher_qa_chain(\n",
-    "    llm=llm,\n",
-    "    graph=graph,\n",
-    ")\n",
+    "chain = create_neptune_opencypher_qa_chain(llm=llm, graph=graph)\n",
+    "\n",
+    "result = chain.invoke(\"How many outgoing routes does the Austin airport have?\")\n",
+    "print(result[\"result\"].content)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### Adding Message History\n",
+    "\n",
+    "The Neptune openCypher QA chain has the ability to be wrapped by [`RunnableWithMessageHistory`](https://python.langchain.com/v0.2/api_reference/core/runnables/langchain_core.runnables.history.RunnableWithMessageHistory.html#langchain_core.runnables.history.RunnableWithMessageHistory). This adds message history to the chain, allowing us to create a chatbot that retains conversation state across multiple invocations.\n",
+    "\n",
+    "To start, we need a way to store and load the message history. For this purpose, each thread will be created as an instance of [`InMemoryChatMessageHistory`](https://python.langchain.com/api_reference/core/chat_history/langchain_core.chat_history.InMemoryChatMessageHistory.html), and stored into a dictionary for repeated access.\n",
+    "\n",
+    "(Also see: https://python.langchain.com/docs/versions/migrating_memory/chat_history/#chatmessagehistory)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from langchain_core.chat_history import InMemoryChatMessageHistory\n",
+    "\n",
+    "chats_by_session_id = {}\n",
+    "\n",
+    "\n",
+    "def get_chat_history(session_id: str) -> InMemoryChatMessageHistory:\n",
+    "    chat_history = chats_by_session_id.get(session_id)\n",
+    "    if chat_history is None:\n",
+    "        chat_history = InMemoryChatMessageHistory()\n",
+    "        chats_by_session_id[session_id] = chat_history\n",
+    "    return chat_history"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Now, the QA chain and message history storage can be used to create the new `RunnableWithMessageHistory`. Note that we must set `query` as the input key to match the format expected by the base chain."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from langchain_core.runnables.history import RunnableWithMessageHistory\n",
+    "\n",
+    "runnable_with_history = RunnableWithMessageHistory(\n",
+    "    chain,\n",
+    "    get_chat_history,\n",
+    "    input_messages_key=\"query\",\n",
+    ")"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Before invoking the chain, a unique `session_id` needs to be generated for the conversation that the new `InMemoryChatMessageHistory` will remember."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import uuid\n",
     "\n",
-    "result = chain.invoke(\n",
-    "    {\"query\": \"How many outgoing routes does the Austin airport have?\"}\n",
+    "session_id = uuid.uuid4()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Finally, invoke the message history enabled chain with the `session_id`."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 8,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "You can fly directly to 98 destinations from Austin airport.\n"
+     ]
+    }
+   ],
+   "source": [
+    "result = runnable_with_history.invoke(\n",
+    "    {\"query\": \"How many destinations can I fly to directly from Austin airport?\"},\n",
+    "    config={\"configurable\": {\"session_id\": session_id}},\n",
+    ")\n",
+    "print(result[\"result\"].content)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "As the chain continues to be invoked with the same `session_id`, responses will be returned in the context of previous queries in the conversation.\n"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 9,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "You can fly directly to 4 destinations in Europe from Austin airport.\n"
+     ]
+    }
+   ],
+   "source": [
+    "result = runnable_with_history.invoke(\n",
+    "    {\"query\": \"Out of those destinations, how many are in Europe?\"},\n",
+    "    config={\"configurable\": {\"session_id\": session_id}},\n",
+    ")\n",
+    "print(result[\"result\"].content)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 10,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "The four European destinations you can fly to directly from Austin airport are:\n",
+      "- AMS (Amsterdam Airport Schiphol)\n",
+      "- FRA (Frankfurt am Main)\n",
+      "- LGW (London Gatwick)\n",
+      "- LHR (London Heathrow)\n"
+     ]
+    }
+   ],
+   "source": [
+    "result = runnable_with_history.invoke(\n",
+    "    {\"query\": \"Give me the codes and names of those airports.\"},\n",
+    "    config={\"configurable\": {\"session_id\": session_id}},\n",
     ")\n",
     "print(result[\"result\"].content)"
    ]
   }
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3 (ipykernel)",
+   "display_name": "Python 3",
    "language": "python",
    "name": "python3"
   },
@@ -111,7 +267,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.10.12"
+   "version": "3.10.13"
   }
  },
  "nbformat": 4,