66 lines
2.7 KiB
TypeScript
66 lines
2.7 KiB
TypeScript
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import type { BaseRetrieverInterface } from "@langchain/core/retrievers";
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import { type Runnable, type RunnableInterface } from "@langchain/core/runnables";
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import type { BaseMessage } from "@langchain/core/messages";
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import type { DocumentInterface, Document } from "@langchain/core/documents";
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/**
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* Parameters for the createRetrievalChain method.
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*/
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export type CreateRetrievalChainParams<RunOutput> = {
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/**
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* Retriever-like object that returns list of documents. Should
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* either be a subclass of BaseRetriever or a Runnable that returns
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* a list of documents. If a subclass of BaseRetriever, then it
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* is expected that an `input` key be passed in - this is what
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* is will be used to pass into the retriever. If this is NOT a
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* subclass of BaseRetriever, then all the inputs will be passed
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* into this runnable, meaning that runnable should take a object
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* as input.
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*/
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retriever: BaseRetrieverInterface | RunnableInterface<Record<string, any>, DocumentInterface[]>;
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/**
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* Runnable that takes inputs and produces a string output.
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* The inputs to this will be any original inputs to this chain, a new
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* context key with the retrieved documents, and chat_history (if not present
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* in the inputs) with a value of `[]` (to easily enable conversational
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* retrieval).
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*/
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combineDocsChain: RunnableInterface<Record<string, any>, RunOutput>;
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};
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/**
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* Create a retrieval chain that retrieves documents and then passes them on.
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* @param {CreateRetrievalChainParams} params A params object
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* containing a retriever and a combineDocsChain.
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* @returns An LCEL Runnable which returns a an object
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* containing at least `context` and `answer` keys.
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* @example
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* ```typescript
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* // yarn add langchain @langchain/openai
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*
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* import { ChatOpenAI } from "@langchain/openai";
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* import { pull } from "langchain/hub";
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* import { createRetrievalChain } from "langchain/chains/retrieval";
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* import { createStuffDocumentsChain } from "langchain/chains/combine_documents";
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*
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* const retrievalQAChatPrompt = await pull("langchain-ai/retrieval-qa-chat");
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* const llm = new ChatOpenAI({});
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* const retriever = ...
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* const combineDocsChain = await createStuffDocumentsChain(...);
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* const retrievalChain = await createRetrievalChain({
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* retriever,
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* combineDocsChain,
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* });
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* const response = await chain.invoke({ input: "..." });
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* ```
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*/
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export declare function createRetrievalChain<RunOutput>({ retriever, combineDocsChain, }: CreateRetrievalChainParams<RunOutput>): Promise<Runnable<{
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input: string;
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chat_history?: BaseMessage[] | string;
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} & {
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[key: string]: unknown;
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}, {
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context: Document[];
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answer: RunOutput;
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} & {
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[key: string]: unknown;
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}>>;
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