mirror of
https://github.com/hwchase17/langchain.git
synced 2025-08-31 18:38:48 +00:00
langchain: deprecate LLMChain, RetrievalQA, and ConversationalRetrievalChain (#20751)
This commit is contained in:
@@ -403,16 +403,13 @@
|
||||
"outputs": [],
|
||||
"source": [
|
||||
"import bs4\n",
|
||||
"from langchain import hub\n",
|
||||
"from langchain.chains import create_history_aware_retriever, create_retrieval_chain\n",
|
||||
"from langchain.chains.combine_documents import create_stuff_documents_chain\n",
|
||||
"from langchain_chroma import Chroma\n",
|
||||
"from langchain_community.chat_message_histories import ChatMessageHistory\n",
|
||||
"from langchain_community.document_loaders import WebBaseLoader\n",
|
||||
"from langchain_core.chat_history import BaseChatMessageHistory\n",
|
||||
"from langchain_core.output_parsers import StrOutputParser\n",
|
||||
"from langchain_core.prompts import ChatPromptTemplate, MessagesPlaceholder\n",
|
||||
"from langchain_core.runnables import RunnablePassthrough\n",
|
||||
"from langchain_core.runnables.history import RunnableWithMessageHistory\n",
|
||||
"from langchain_openai import ChatOpenAI, OpenAIEmbeddings\n",
|
||||
"from langchain_text_splitters import RecursiveCharacterTextSplitter\n",
|
||||
|
@@ -7,6 +7,7 @@ from abc import abstractmethod
|
||||
from pathlib import Path
|
||||
from typing import Any, Callable, Dict, List, Optional, Tuple, Type, Union
|
||||
|
||||
from langchain_core._api import deprecated
|
||||
from langchain_core.callbacks import (
|
||||
AsyncCallbackManagerForChainRun,
|
||||
CallbackManagerForChainRun,
|
||||
@@ -233,9 +234,84 @@ class BaseConversationalRetrievalChain(Chain):
|
||||
super().save(file_path)
|
||||
|
||||
|
||||
@deprecated(
|
||||
since="0.1.17",
|
||||
alternative=(
|
||||
"create_history_aware_retriever together with create_retrieval_chain "
|
||||
"(see example in docstring)"
|
||||
),
|
||||
removal="0.3.0",
|
||||
)
|
||||
class ConversationalRetrievalChain(BaseConversationalRetrievalChain):
|
||||
"""Chain for having a conversation based on retrieved documents.
|
||||
|
||||
This class is deprecated. See below for an example implementation using
|
||||
`create_retrieval_chain`. Additional walkthroughs can be found at
|
||||
https://python.langchain.com/docs/use_cases/question_answering/chat_history
|
||||
|
||||
.. code-block:: python
|
||||
|
||||
from langchain.chains import (
|
||||
create_history_aware_retriever,
|
||||
create_retrieval_chain,
|
||||
)
|
||||
from langchain.chains.combine_documents import create_stuff_documents_chain
|
||||
from langchain_core.prompts import ChatPromptTemplate, MessagesPlaceholder
|
||||
from langchain_openai import ChatOpenAI
|
||||
|
||||
|
||||
retriever = ... # Your retriever
|
||||
|
||||
llm = ChatOpenAI()
|
||||
|
||||
# Contextualize question
|
||||
contextualize_q_system_prompt = (
|
||||
"Given a chat history and the latest user question "
|
||||
"which might reference context in the chat history, "
|
||||
"formulate a standalone question which can be understood "
|
||||
"without the chat history. Do NOT answer the question, just "
|
||||
"reformulate it if needed and otherwise return it as is."
|
||||
)
|
||||
contextualize_q_prompt = ChatPromptTemplate.from_messages(
|
||||
[
|
||||
("system", contextualize_q_system_prompt),
|
||||
MessagesPlaceholder("chat_history"),
|
||||
("human", "{input}"),
|
||||
]
|
||||
)
|
||||
history_aware_retriever = create_history_aware_retriever(
|
||||
llm, retriever, contextualize_q_prompt
|
||||
)
|
||||
|
||||
# Answer question
|
||||
qa_system_prompt = (
|
||||
"You are an assistant for question-answering tasks. Use "
|
||||
"the following pieces of retrieved context to answer the "
|
||||
"question. If you don't know the answer, just say that you "
|
||||
"don't know. Use three sentences maximum and keep the answer "
|
||||
"concise."
|
||||
"\n\n"
|
||||
"{context}"
|
||||
)
|
||||
qa_prompt = ChatPromptTemplate.from_messages(
|
||||
[
|
||||
("system", qa_system_prompt),
|
||||
MessagesPlaceholder("chat_history"),
|
||||
("human", "{input}"),
|
||||
]
|
||||
)
|
||||
# Below we use create_stuff_documents_chain to feed all retrieved context
|
||||
# into the LLM. Note that we can also use StuffDocumentsChain and other
|
||||
# instances of BaseCombineDocumentsChain.
|
||||
question_answer_chain = create_stuff_documents_chain(llm, qa_prompt)
|
||||
rag_chain = create_retrieval_chain(
|
||||
history_aware_retriever, question_answer_chain
|
||||
)
|
||||
|
||||
# Usage:
|
||||
chat_history = [] # Collect chat history here (a sequence of messages)
|
||||
rag_chain.invoke({"input": query, "chat_history": chat_history})
|
||||
|
||||
This chain takes in chat history (a list of messages) and new questions,
|
||||
and then returns an answer to that question.
|
||||
The algorithm for this chain consists of three parts:
|
||||
|
@@ -4,6 +4,7 @@ from __future__ import annotations
|
||||
import warnings
|
||||
from typing import Any, Dict, List, Optional, Sequence, Tuple, Union, cast
|
||||
|
||||
from langchain_core._api import deprecated
|
||||
from langchain_core.callbacks import (
|
||||
AsyncCallbackManager,
|
||||
AsyncCallbackManagerForChainRun,
|
||||
@@ -34,9 +35,31 @@ from langchain_core.utils.input import get_colored_text
|
||||
from langchain.chains.base import Chain
|
||||
|
||||
|
||||
@deprecated(
|
||||
since="0.1.17",
|
||||
alternative="RunnableSequence, e.g., `prompt | llm`",
|
||||
removal="0.3.0",
|
||||
)
|
||||
class LLMChain(Chain):
|
||||
"""Chain to run queries against LLMs.
|
||||
|
||||
This class is deprecated. See below for an example implementation using
|
||||
LangChain runnables:
|
||||
|
||||
.. code-block:: python
|
||||
|
||||
from langchain_core.prompts import PromptTemplate
|
||||
from langchain_openai import OpenAI
|
||||
|
||||
prompt_template = "Tell me a {adjective} joke"
|
||||
prompt = PromptTemplate(
|
||||
input_variables=["adjective"], template=prompt_template
|
||||
)
|
||||
llm = OpenAI()
|
||||
chain = prompt | llm
|
||||
|
||||
chain.invoke("your adjective here")
|
||||
|
||||
Example:
|
||||
.. code-block:: python
|
||||
|
||||
|
@@ -6,6 +6,7 @@ import warnings
|
||||
from abc import abstractmethod
|
||||
from typing import Any, Dict, List, Optional
|
||||
|
||||
from langchain_core._api import deprecated
|
||||
from langchain_core.callbacks import (
|
||||
AsyncCallbackManagerForChainRun,
|
||||
CallbackManagerForChainRun,
|
||||
@@ -194,9 +195,41 @@ class BaseRetrievalQA(Chain):
|
||||
return {self.output_key: answer}
|
||||
|
||||
|
||||
@deprecated(since="0.1.17", alternative="create_retrieval_chain", removal="0.3.0")
|
||||
class RetrievalQA(BaseRetrievalQA):
|
||||
"""Chain for question-answering against an index.
|
||||
|
||||
This class is deprecated. See below for an example implementation using
|
||||
`create_retrieval_chain`:
|
||||
|
||||
.. code-block:: python
|
||||
|
||||
from langchain.chains import create_retrieval_chain
|
||||
from langchain.chains.combine_documents import create_stuff_documents_chain
|
||||
from langchain_core.prompts import ChatPromptTemplate
|
||||
from langchain_openai import ChatOpenAI
|
||||
|
||||
|
||||
retriever = ... # Your retriever
|
||||
llm = ChatOpenAI()
|
||||
|
||||
system_prompt = (
|
||||
"Use the given context to answer the question. "
|
||||
"If you don't know the answer, say you don't know. "
|
||||
"Use three sentence maximum and keep the answer concise."
|
||||
"\n\n{context}"
|
||||
)
|
||||
prompt = ChatPromptTemplate.from_messages(
|
||||
[
|
||||
("system", system_prompt),
|
||||
("human", "{input}"),
|
||||
]
|
||||
)
|
||||
question_answer_chain = create_stuff_documents_chain(llm, prompt)
|
||||
chain = create_retrieval_chain(retriever, question_answer_chain)
|
||||
|
||||
chain.invoke({"input": query})
|
||||
|
||||
Example:
|
||||
.. code-block:: python
|
||||
|
||||
|
Reference in New Issue
Block a user