ModuleNotFoundError: No module named 'langchain_openai'

Question

Following LangChain docs in my Jupyter notebook with the following code :

from langchain_openai import ChatOpenAI
from langchain_core.prompts import ChatPromptTemplate
from langchain_core.output_parsers import StrOutputParser


prompt = ChatPromptTemplate.from_template("Tell me a short joke about {topic}")
model = ChatOpenAI(model="gpt-3.5-turbo")
output_parser = StrOutputParser()

chain = prompt | model | output_parser

Docs say that pip install langchain installs all necessary modules, including langchain-community and langchain-core

However, I get this error:

ModuleNotFoundError: No module named 'langchain_openai'

Answer 1

In addition to Ari response, from LangChain version 0.0.10, the ChatOpenAI from the langchain-community package has been deprecated and it will be soon removed from that same package (see: Python API):

[docs]@deprecated(
    since="0.0.10", 
    removal="0.2.0", 
    alternative_import="langchain_openai.ChatOpenAI"
)
class ChatOpenAI(BaseChatModel):

The correct usage of the class can be found in the langchain-openai package, which (for some reasons...) does not come by default when installing LangChain from PyPI. The package is the following: OpenAI Integration.

You can directly install the package by running:

pip install langchain-openai

LangChain is continuously evolving so it is generally difficult to keep the pace of those changing. I suggest to always refer to the official documentation for understanding where to find classes and functions based on the specific version of LangChain installed.