Class RetrievalQAChain

Deprecated

This class will be removed in 0.3.0. See below for an example implementation using createRetrievalChain: Class representing a chain for performing question-answering tasks with a retrieval component.

Example

import { createStuffDocumentsChain } from "langchain/chains/combine_documents";
import { ChatPromptTemplate } from "@langchain/core/prompts";
import { createRetrievalChain } from "langchain/chains/retrieval";
import { MemoryVectorStore } from "langchain/vectorstores/memory";

const documents = [...your documents here];
const embeddings = ...your embeddings model;
const llm = ...your LLM model;

const vectorstore = await MemoryVectorStore.fromDocuments(
  documents,
  embeddings
);
const prompt = ChatPromptTemplate.fromTemplate(`Answer the user's question: {input}`);

const combineDocsChain = await createStuffDocumentsChain({
  llm,
  prompt,
});
const retriever = vectorstore.asRetriever();

const retrievalChain = await createRetrievalChain({
  combineDocsChain,
  retriever,
});

Hierarchy (view full)

Implements

Constructors

constructor

Properties

combineDocumentsChain inputKey retriever returnSourceDocuments memory?

Accessors

inputKeys outputKeys

Methods

apply call invoke prepOutputs run serialize deserialize fromLLM

Constructors

constructor

Properties

combineDocumentsChain

combineDocumentsChain: BaseChain<ChainValues, ChainValues>

inputKey

inputKey: string = "query"

retriever

retriever: BaseRetrieverInterface

returnSourceDocuments

returnSourceDocuments: boolean = false

Optional memory

memory?: any

Accessors

inputKeys

outputKeys

Methods

apply

  • apply(inputs, config?): Promise<ChainValues[]>

  • Parameters

    • inputs: ChainValues[]
    • Optional config: any[]

    Returns Promise<ChainValues[]>

    ⚠️ Deprecated ⚠️

    Use .batch() instead. Will be removed in 0.2.0.

    This feature is deprecated and will be removed in the future.

    It is not recommended for use.

    Call the chain on all inputs in the list

call

  • call(values, config?, tags?): Promise<ChainValues>

  • Parameters

    • values: any
    • Optional config: any
    • Optional tags: string[]

      Deprecated

    Returns Promise<ChainValues>

    Deprecated

    Use .invoke() instead. Will be removed in 0.2.0.

    Run the core logic of this chain and add to output if desired.

    Wraps _call and handles memory.

invoke

  • invoke(input, options?): Promise<ChainValues>

  • Invoke the chain with the provided input and returns the output.

    Parameters

    • input: ChainValues

      Input values for the chain run.

    • Optional options: any

    Returns Promise<ChainValues>

    Promise that resolves with the output of the chain run.

prepOutputs

  • prepOutputs(inputs, outputs, returnOnlyOutputs?): Promise<Record<string, unknown>>

  • Parameters

    • inputs: Record<string, unknown>
    • outputs: Record<string, unknown>
    • returnOnlyOutputs: boolean = false

    Returns Promise<Record<string, unknown>>

run

  • run(input, config?): Promise<string>

  • Parameters

    • input: any
    • Optional config: any

    Returns Promise<string>

    Deprecated

    Use .invoke() instead. Will be removed in 0.2.0.

serialize

Static deserialize

Static fromLLM

  • fromLLM(llm, retriever, options?): RetrievalQAChain

  • Creates a new instance of RetrievalQAChain using a BaseLanguageModel and a BaseRetriever.

    Parameters

    • llm: BaseLanguageModelInterface

      The BaseLanguageModel used to generate a new question.

    • retriever: BaseRetrieverInterface

      The BaseRetriever used to retrieve relevant documents.

    • Optional options: Partial<Omit<RetrievalQAChainInput, "retriever" | "index" | "combineDocumentsChain">> & StuffQAChainParams

      Optional parameters for the RetrievalQAChain.

    Returns RetrievalQAChain

    A new instance of RetrievalQAChain.

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