Repository: explodinggradients/ragas
Issue: [R-242] trouble in importing pydantic_output_parser from langchain
Root cause: External Dependency Breakage

**Describe the bug**
Once ragas is installed I want to import it and I got an error on the import of pydantic output parser from langchain.
Ragas version: 0.1.6
Python version: 3.10
LangChain version: 0.1.14

**Code to Reproduce**
`import ragas`

**Error trace**
`---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
Cell In[6], line 1
----> 1 import ragas

File /anaconda/envs/azureml_py310_langchain/lib/python3.10/site-packages/ragas/__init__.py:1
----> 1 from ragas.adaptation import adapt
      2 from ragas.evaluation import evaluate
      3 from ragas.run_config import RunConfig

File /anaconda/envs/azureml_py310_langchain/lib/python3.10/site-packages/ragas/adaptation.py:7
      5 from ragas.llms import llm_factory
      6 from ragas.llms.base import BaseRagasLLM, LangchainLLMWrapper
----> 7 from ragas.metrics.base import MetricWithLLM
     10 def adapt(
     11     metrics: t.List[MetricWithLLM],
     12     language: str,
     13     llm: t.Optional[BaseRagasLLM] = None,
     14     cache_dir: t.Optional[str] = None,
     15 ) -> None:
     16     """
     17     Adapt the metric to a different language.
     18     """

File /anaconda/envs/azureml_py310_langchain/lib/python3.10/site-packages/ragas/metrics/__init__.py:1
----> 1 from ragas.metrics._answer_correctness import AnswerCorrectness, answer_correctness
      2 from ragas.metrics._answer_relevance import AnswerRelevancy, answer_relevancy
      3 from ragas.metrics._answer_similarity import AnswerSimilarity, answer_similarity

File /anaconda/envs/azureml_py310_langchain/lib/python3.10/site-packages/ragas/metrics/_answer_correctness.py:10
      7 import numpy as np
      8 from langchain_core.pydantic_v1 import BaseModel
---> 10 from ragas.llms.output_parser import RagasoutputParser, get_json_format_instructions
     11 from ragas.llms.prompt import Prompt
     12 from ragas.metrics._answer_similarity import AnswerSimilarity

File /anaconda/envs/azureml_py310_langchain/lib/python3.10/site-packages/ragas/llms/output_parser.py:6
      3 import typing as t
      5 from langchain_core.exceptions import OutputParserException
----> 6 from langchain_core.output_parsers import PydanticOutputParser
      7 from langchain_core.pydantic_v1 import BaseModel
      9 from ragas.llms import BaseRagasLLM

ImportError: cannot import name 'PydanticOutputParser' from 'langchain_core.output_parsers' (/anaconda/envs/azureml_py310_langchain/lib/python3.10/site-packages/langchain_core/output_parsers/__init__.py)`

**Expected behavior**
I expect the import to be without any errors. A quick fix would be to change the import in the file: ragas/tree/main/src/ragas/llms/output_parser.py
from 
`from langchain_core.output_parsers import PydanticOutputParser`
to
`from langchain.output_parsers import PydanticOutputParser`


<sub>[R-242](https://linear.app/exploding-gradients/issue/R-242/trouble-in-importing-pydantic-output-parser-from-langchain)</sub>

hey @kluskaj that is very strange - could you share which version of langchain core you have too?
try updating is as well?

I'll debug this in the mean time as well

Hey @jjmachan,
The version of langchain_core was: 0.1.22
Updating to 0.1.40 indeed solved the problem.
Sorry, should I have tried that...

updating langchain-core did not resolve the problem for me:

Python version: 3.8
Ragas version==0.1.7
langchain==0.1.1
langchain-community==0.0.16
langchain-core==0.1.40
langchain-openai==0.0.6

We're getting this too

I have the same problem

I was able to have it running with langchain-core==0.1.45.

seems like we have to pin the langchain-core version for this as the solution

will do that

Updating langchain_core, doesnt help

this is ok:
ragas==0.1.8
langchain == 0.1.20 
langchain-community ==0.38 
langchain-core==0.1.52 
langchain-openai == 0.0.8  
langchain-text-splitters==0.0.2 
langsmith == 0.1.77

closing this now 🙂