[Python] Resolve no validator found for <class '__main__.Resume'>, see...

Getting the no validator found error with the following code. Here are the Library versions:

LangChain version: 0.0.284
Pydantic version: 2.8.2


Code:

from typing import Optional
from pydantic import BaseModel, Field, ValidationError
from config import set_environment
from langchain.chains import create_extraction_chain_pydantic
from langchain.chat_models import ChatOpenAI
from langchain.document_loaders import PyPDFLoader

class Resume(BaseModel):
first_name: Optional[str] = Field(None, description="First Name")
last_name: Optional[str] = Field(None, description="Last Name")
email: Optional[str] = Field(None, description="Email Address")
phone: Optional[str] = Field(None, description="Phone Number")

class Config:
arbitrary_types_allowed = True


set_environment()

# Sample Data
sample_data = {
"first_name": "John",
"last_name": "Doe",
"email": "john.doe@example.com",
"phone": "123-456-7890"
}

# Validate resume
try:
resume = Resume(**sample_data)
print("Validation successful:", resume)
except ValidationError as e:
print("Validation error:", e)

pdf_file_path = "laverne-resume.pdf"
pdf_loader = PyPDFLoader(pdf_file_path)
docs = pdf_loader.load_and_split()

chat_model = ChatOpenAI(model_name="gpt-3.5-turbo")
chain = create_extraction_chain_pydantic(pydantic_schema=Resume, llm=chat_model)
resp = chain.run(docs)
print(resp)


Error:

Traceback (most recent call last):
File "/ch4/information_extraction.py", line 56, in <module>
chain = create_extraction_chain_pydantic(pydantic_schema=Resume, llm=chat_model)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "ws/gen-ai/venv/lib/python3.12/site-packages/langchain/chains/openai_functions/extraction.py", line 97, in create_extraction_chain_pydantic
class PydanticSchema(BaseModel):
File "ws/gen-ai/venv/lib/python3.12/site-packages/pydantic/v1/main.py", line 197, in __new__
fields[ann_name] = ModelField.infer(
^^^^^^^^^^^^^^^^^
File "ws/gen-ai/venv/lib/python3.12/site-packages/pydantic/v1/fields.py", line 504, in infer
return cls(
^^^^
File "ws/gen-ai/venv/lib/python3.12/site-packages/pydantic/v1/fields.py", line 434, in __init__
self.prepare()
File "ws/gen-ai/venv/lib/python3.12/site-packages/pydantic/v1/fields.py", line 550, in prepare
self._type_analysis()
File "ws/gen-ai/venv/lib/python3.12/site-packages/pydantic/v1/fields.py", line 756, in _type_analysis
self.sub_fields = [self._create_sub_type(self.type_, '_' + self.name)]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "ws/gen-ai/venv/lib/python3.12/site-packages/pydantic/v1/fields.py", line 806, in _create_sub_type
return self.__class__(
^^^^^^^^^^^^^^^
File "ws/gen-ai/venv/lib/python3.12/site-packages/pydantic/v1/fields.py", line 434, in __init__
self.prepare()
File "ws/gen-ai/venv/lib/python3.12/site-packages/pydantic/v1/fields.py", line 555, in prepare
self.populate_validators()
File "ws/gen-ai/venv/lib/python3.12/site-packages/pydantic/v1/fields.py", line 829, in populate_validators
*(get_validators() if get_validators else list(find_validators(self.type_, self.model_config))),
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "ws/gen-ai/venv/lib/python3.12/site-packages/pydantic/v1/validators.py", line 765, in find_validators
raise RuntimeError(f'no validator found for {type_}, see `arbitrary_types_allowed` in Config')
RuntimeError: no validator found for <class '__main__.Resume'>, see `arbitrary_types_allowed` in Config

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