Langserve, throws 500 error when sending a request because of a lentgh one malformed dictionary.

[Louw123]

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Example Code

discord test.py

from langserve import RemoteRunnable
async def abcdefg(ctx):
     channel = bot.get_channel(1265486547227115613)
     try:
          remote_chain=RemoteRunnable("http://localhost:8000/chain/")
          output = remote_chain.invoke("a+b=b+a")
          print(output)
          await channel.send(output)
     except Exception as e:
          await channel.send("Oops, we have an error: " + str(e))
     await channel.send(output)
...
lang.py

app = FastAPI(
  title="LangChain Server",
  version="1.0",
  description="A simple API server using LangChain's Runnable interfaces",
)


add_routes(
    app,
    chain,
    path="/chain",

)

if __name__ == "__main__":
    import uvicorn

Description

im trying to use langserve's RemoteRunnable. However when I run the function it throws a: Server error '500 Internal Server Error' for url 'http://localhost:8000/chain/invoke' For more information check: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/500 for Internal Server Error Then I checked the code in the lang.py file. That file also threw an error:

Traceback (most recent call last):
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/pydantic/v1/main.py", line 716, in validate
    value_as_dict = dict(value)
                    ^^^^^^^^^^^
ValueError: dictionary update sequence element #0 has length 1; 2 is required

That lead to:

Traceback (most recent call last):
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/uvicorn/protocols/http/httptools_impl.py", line 399, in run_asgi
    result = await app(  # type: ignore[func-returns-value]
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/uvicorn/middleware/proxy_headers.py", line 70, in __call__
    return await self.app(scope, receive, send)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/fastapi/applications.py", line 1054, in __call__
    await super().__call__(scope, receive, send)
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/starlette/applications.py", line 123, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/starlette/middleware/errors.py", line 186, in __call__
    raise exc
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/starlette/middleware/errors.py", line 164, in __call__
    await self.app(scope, receive, _send)
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/starlette/middleware/exceptions.py", line 65, in __call__
    await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/starlette/_exception_handler.py", line 64, in wrapped_app
    raise exc
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    await app(scope, receive, sender)
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/starlette/routing.py", line 756, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/starlette/routing.py", line 776, in app
    await route.handle(scope, receive, send)
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/starlette/routing.py", line 297, in handle
    await self.app(scope, receive, send)
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/starlette/routing.py", line 77, in app
    await wrap_app_handling_exceptions(app, request)(scope, receive, send)
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/starlette/_exception_handler.py", line 64, in wrapped_app
    raise exc
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
    await app(scope, receive, sender)
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/starlette/routing.py", line 72, in app
    response = await func(request)
               ^^^^^^^^^^^^^^^^^^^
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/fastapi/routing.py", line 278, in app
    raw_response = await run_endpoint_function(
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/fastapi/routing.py", line 191, in run_endpoint_function
    return await dependant.call(**values)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/langserve/server.py", line 530, in invoke
    return await api_handler.invoke(request)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/langserve/api_handler.py", line 802, in invoke
    config, input_ = await self._get_config_and_input(
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/langserve/api_handler.py", line 778, in _get_config_and_input
    input_ = schema.validate(body.input)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/louismcmaster/PycharmProjects/lngchnwrk/.venv/lib/python3.12/site-packages/pydantic/v1/main.py", line 718, in validate
    raise DictError() from e
pydantic.v1.errors.DictError: value is not a valid dict

System Info

potential sources:

langserve==0.2.2
uvicorn==0.30.1

other:

aiohttp==3.9.5
aiosignal==1.3.1
annotated-types==0.7.0
anyio==4.4.0
attrs==23.2.0
beautifulsoup4==4.12.3
certifi==2024.7.4
charset-normalizer==3.3.2
click==8.1.7
dataclasses-json==0.6.7
discord==2.3.2
discord.py==2.4.0
distro==1.9.0
dnspython==2.6.1
email_validator==2.2.0
fastapi==0.111.0
fastapi-cli==0.0.4
fireworks-ai==0.14.0
frozenlist==1.4.1
greenlet==3.0.3
h11==0.14.0
httpcore==1.0.5
httptools==0.6.1
httpx==0.27.0
httpx-sse==0.4.0
idna==3.7
iniconfig==2.0.0
Jinja2==3.1.4
jsonpatch==1.33
jsonpointer==3.0.0
jsonschema==4.23.0
jsonschema-specifications==2023.12.1
langchain==0.2.7
langchain-community==0.2.7
langchain-core==0.2.13
langchain-fireworks==0.1.4
langchain-text-splitters==0.2.2
langsmith==0.1.85
markdown-it-py==3.0.0
MarkupSafe==2.1.5
marshmallow==3.21.3
mdurl==0.1.2
multidict==6.0.5
mypy-extensions==1.0.0
numpy==1.26.4
openai==1.35.13
orjson==3.10.6
packaging==24.1
pillow==10.4.0
playwright==1.45.0
pluggy==1.5.0
pydantic==2.8.2
pydantic_core==2.20.1
pyee==11.1.0
Pygments==2.18.0
pyproject-toml==0.0.10
pytest==8.2.2
pytest-base-url==2.1.0
pytest-playwright==0.5.1
python-dotenv==1.0.1
python-multipart==0.0.9
python-slugify==8.0.4
PyYAML==6.0.1
referencing==0.35.1
requests==2.32.3
rich==13.7.1
rpds-py==0.19.0
setuptools==70.3.0
shellingham==1.5.4
sniffio==1.3.1
soupsieve==2.5
SQLAlchemy==2.0.31
sse-starlette==2.1.2
starlette==0.37.2
tenacity==8.5.0
text-unidecode==1.3
toml==0.10.2
tqdm==4.66.4
typer==0.12.3
typing-inspect==0.9.0
typing_extensions==4.12.2
ujson==5.10.0
urllib3==2.2.2
uvloop==0.19.0
watchfiles==0.22.0
websockets==12.0
wheel==0.43.0
yarl==1.9.4

[dosubot[bot]]

Hello, @Louw123! I'm here to assist you with your bug, answer questions, and guide you on contributing. Let's work together to solve this issue.

To resolve the 500 Internal Server Error and the pydantic.v1.errors.DictError when using Langserve's RemoteRunnable, ensure that the correct version of Pydantic is being imported. Here is a code snippet that shows a conditional import to handle this:

try:
    from pydantic.v1.main import *  # noqa: F403
except ImportError:
    from pydantic.main import *  # type: ignore # noqa: F403

Additionally, check your repository for any direct imports from Pydantic and replace them with imports from langchain_core.pydantic_v1. You can use the following script to identify and update these imports:

#!/bin/bash
#
# This script searches for lines starting with "import pydantic" or "from pydantic"
# in tracked files within a Git repository.
#
# Usage: ./scripts/check_pydantic.sh /path/to/repository

# Check if a path argument is provided
if [ $# -ne 1 ]; then
  echo "Usage: $0 /path/to/repository"
  exit 1
fi

repository_path="$1"

# Search for lines matching the pattern within the specified repository
result=$(git -C "$repository_path" grep -E '^import pydantic|^from pydantic')

# Check if any matching lines were found
if [ -n "$result" ]; then
  echo "ERROR: The following lines need to be updated:"
  echo "$result"
  echo "Please replace the code with an import from langchain_core.pydantic_v1."
  echo "For example, replace 'from pydantic import BaseModel'"
  echo "with 'from langchain_core.pydantic_v1 import BaseModel'"
  exit 1
fi

Ensure that your environment has the correct version of Pydantic installed that supports pydantic.v1.main. If you are using Pydantic v2, you might need to adjust your imports or ensure compatibility with the version of LangChain you are using ^[1][2].

LangChain's Runnable interface includes methods like invoke, stream, batch, and their async counterparts (ainvoke, astream, abatch). These methods use Pydantic models for input and output schemas, which are auto-generated from the structure of the Runnable. Ensure that your input and output schemas are correctly defined to avoid validation errors ^[3].

To continue talking to Dosu, mention @dosu.