docs: update streaming from within the tool to use dispatch_custom_event (#1000)

examples/streaming-events-from-within-tools-without-langchain.ipynb

@@ -42,7 +42,7 @@
    "metadata": {},
    "outputs": [
     {
-     "name": "stdout",
+     "name": "stdin",
      "output_type": "stream",
      "text": [
       "OPENAI_API_KEY:  ········\n"
@@ -80,7 +80,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 3,
    "id": "d59234f9-173e-469d-a725-c13e0979663e",
    "metadata": {},
    "outputs": [],
@@ -181,19 +181,16 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 4,
    "id": "b90941d8-afe4-42ec-9262-9c3b87c3b1ec",
    "metadata": {},
    "outputs": [],
    "source": [
     "import json\n",
-    "from langchain_core.runnables import RunnableLambda\n",
+    "from langchain_core.callbacks import adispatch_custom_event\n",
     "\n",
     "async def get_items(place: str) -> str:\n",
     "    \"\"\"Use this tool to look up which items are in the given place.\"\"\"\n",
-    "    # NOTE: we need to define a special langchain runnable that we'll be using for logging the streaming outputs from within a tool\n",
-    "    tool_logger = RunnableLambda(lambda inputs: inputs).with_config({\"tags\": [\"tool_call\"]})\n",
-    "\n",
     "    # this can be replaced with any actual streaming logic that you might have\n",
     "    def stream(place: str):\n",
     "        if \"bed\" in place:  # For under the bed\n",
@@ -205,7 +202,13 @@
     "\n",
     "    tokens = []\n",
     "    for token in stream(place):\n",
-    "        tool_logger.invoke(token)\n",
+    "        await adispatch_custom_event(\n",
+    "            # this will allow you to filter events by name\n",
+    "            \"tool_call_token_stream\",\n",
+    "            {\"function_name\": \"get_items\", \"arguments\": {\"place\": place}, \"tool_output_token\": token},\n",
+    "            # this will allow you to filter events by tags\n",
+    "            config={\"tags\": [\"tool_call\"]}\n",
+    "        )\n",
     "        tokens.append(token)\n",
     "\n",
     "    return \", \".join(tokens)\n",
@@ -245,7 +248,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 5,
    "id": "228260be-1f9a-4195-80e0-9604f8a5dba6",
    "metadata": {},
    "outputs": [],
@@ -284,10 +287,18 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 16,
+   "execution_count": 6,
    "id": "45c96a79-4147-42e3-89fd-d942b2b49f6c",
    "metadata": {},
    "outputs": [
+    {
+     "name": "stderr",
+     "output_type": "stream",
+     "text": [
+      "/Users/vadymbarda/.virtualenvs/langgraph/lib/python3.11/site-packages/langchain_core/_api/beta_decorator.py:87: LangChainBetaWarning: This API is in beta and may change in the future.\n",
+      "  warn_beta(\n"
+     ]
+    },
     {
      "name": "stdout",
      "output_type": "stream",
@@ -301,8 +312,8 @@
    "source": [
     "async for event in graph.astream_events({\"messages\": [{\"role\": \"user\", \"content\": \"what's in the bedroom\"}]}, version=\"v2\"):\n",
     "    tags = event.get(\"tags\", [])\n",
-    "    if event[\"event\"] == \"on_chain_end\" and \"tool_call\" in tags:\n",
-    "        print(\"Tool token\", event[\"data\"][\"output\"])"
+    "    if event[\"event\"] == \"on_custom_event\" and \"tool_call\" in tags:\n",
+    "        print(\"Tool token\", event[\"data\"][\"tool_output_token\"])"
    ]
   }
  ],