docs/how_to/pydantic_compatibility/

[giscus[bot]]

docs/how_to/pydantic_compatibility/

As of the 0.3 release, LangChain uses Pydantic 2 internally.

https://python.langchain.com/docs/how_to/pydantic_compatibility/

[Lars-Loewenzahn]

Hey, my Programm isn't working anymore, after updating Langchain. I am using kor. Kor is using pydantic.

How can I get help to get it running again?

[eyurtsev]

Create an issue with https://github.com/eyurtsev/kor/issues and include a MRE and a traceback. kor is compatible with pydantic 2.

[maktaurus]

import os
from langchain_core.prompts import PromptTemplate
from langchain_openai import ChatOpenAI
from langchain_ollama import OllamaLLM
from dotenv import load_dotenv

if name=="main":
load_dotenv()
print("hello langchain")
topic = "Aeroplane"

chat_template = "Tell a joke on {topic}"
chat_prompt = PromptTemplate(input_variables=["topic"], template=chat_template)

llm = OllamaLLM(model="llama3.2")
print(llm.invoke("The first man on the moon was ..."))

The above code is failling with below error:

pydantic_core._pydantic_core.ValidationError: 2 validation errors for GenerateRequest
format.literal['json']
Input should be 'json' [type=literal_error, input_value='', input_type=str]
For further information visit https://errors.pydantic.dev/2.10/v/literal_error
format.dict[str,any]
Input should be a valid dictionary [type=dict_type, input_value='', input_type=str]
For further information visit https://errors.pydantic.dev/2.10/v/dict_type

[maktaurus]

Please ignore these below lines from above code:
topic = "Aeroplane"

chat_template = "Tell a joke on {topic}"
chat_prompt = PromptTemplate(input_variables=["topic"], template=chat_template)