SlackToolkit Problem - sample code does not work

[edwardgonen]

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Example Code

from langchain_community.agent_toolkits import SlackToolkit

toolkit = SlackToolkit()

Description

I have the
SLACK_USER_TOKEN= set correctly and installed all the needed packages including slack_sdk
But the SlackToolkin() gives exception:
Exception has occurred: PydanticUserError
SlackToolkit is not fully defined; you should define WebClient, then call SlackToolkit.model_rebuild().

For further information visit https://errors.pydantic.dev/2.10/u/class-not-fully-defined
File "/Users/user/Projects/slack/main.py", line 13, in
toolkit = SlackToolkit()
^^^^^^^^^^^^^^
pydantic.errors.PydanticUserError: SlackToolkit is not fully defined; you should define WebClient, then call SlackToolkit.model_rebuild().

For further information visit https://errors.pydantic.dev/2.10/u/class-not-fully-defined

I've tried to add WebClient but then fail on get_tools().

Can anyone help?

System Info

langchain==0.3.8
langchain-anthropic==0.3.0
langchain-community==0.3.8
langchain-core==0.3.21
langchain-experimental==0.3.3
langchain-openai==0.2.10
langchain-text-splitters==0.3.2

MAC

Python 3.12.3

[edwardgonen]

from langchain_community.agent_toolkits import SlackToolkit
from slack_sdk import WebClient

client = WebClient(token="my token")

# Create and configure SlackToolkit
toolkit = SlackToolkit(
    client=client,
    default_channel=None
)

# Rebuild the model to ensure proper configuration
SlackToolkit.model_rebuild()
tools = toolkit.get_tools() 

The last line gives:

Traceback (most recent call last):
File "/Users/edgonen/Projects/AI/agents/multiagentnetwork/venv/lib/python3.12/site-packages/langchain_community/agent_toolkits/slack/toolkit.py", line 101, in get_tools
SlackGetChannel(),
^^^^^^^^^^^^^^^^^
File "/Users/edgonen/Projects/AI/agents/multiagentnetwork/venv/lib/python3.12/site-packages/langchain_core/tools/base.py", line 432, in init
super().init(**kwargs)
File "/Users/edgonen/Projects/AI/agents/multiagentnetwork/venv/lib/python3.12/site-packages/langchain_core/load/serializable.py", line 125, in init
super().init(*args, **kwargs)
File "/Users/edgonen/Projects/AI/agents/multiagentnetwork/venv/lib/python3.12/site-packages/pydantic/main.py", line 214, in init
validated_self = self.pydantic_validator.validate_python(data, self_instance=self)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/edgonen/Projects/AI/agents/multiagentnetwork/venv/lib/python3.12/site-packages/pydantic/_internal/_mock_val_ser.py", line 100, in getattr
raise PydanticUserError(self._error_message, code=self._code)
pydantic.errors.PydanticUserError: SlackGetChannel is not fully defined; you should define WebClient, then call SlackGetChannel.model_rebuild().

For further information visit https://errors.pydantic.dev/2.10/u/class-not-fully-defined

I'm not sure if this code addition is needed as the sample code talks just about:

from langchain_community.agent_toolkits import SlackToolkit

toolkit = SlackToolkit()

[feijoes]

try update the pydantic to the lastest version:

pip install -U pydantic

[edwardgonen]

Thanks for trying to help. Updated pedantic and still the same message... Does it just work on your side? It is so strange. Just 3-4 lines of code and luck...

[edwardgonen]

I've tried that before:

from slack_sdk import WebClient
from langchain_community.agent_toolkits import SlackToolkit

slack_client = WebClient(token="my token")

toolkit = SlackToolkit(client=slack_client)
tools = toolkit.get_tools()


Then it fails on   tools = toolkit.get_tools()

Exception has occurred: PydanticUserError

SlackGetChannel is not fully defined; you should define WebClient, then call SlackGetChannel.model_rebuild().

I'm just wondering if it works for anyone as described in the doc...

[edwardgonen]

BTW - got a mail from Slack right now, that my token is disabled. I'll need to reissue a new one. Anyway it does not work...

[edwardgonen]

Renewed my token. Still the same problem

[feijoes]

I am not completely sure, but I think it might be a dependency or Python version issue. Try downgrading LangChain, Pydantic, or Python to an older version.

[edwardgonen]

Well. I've been using Python 3.12 (the same I use for this test) for a long time with many langchain and langgraphs projects without any problem. Unfortunately downgrading is not an option for me. I'm also skeptical that it might be related. I'm just wondering how langchain could release something so untested - and I see that this Slack toolkit is available since langchain 0.1. So something is really weird here....

[JLoweAI]

I have the same problem as edwardgonen

[ccurme]

I can replicate this and believe it is related to an update in Pydantic's validation.

Created an issue to track: #28989

PR to resolve: #28990