Class ConversationalRetrievalQAChain

Class for conducting conversational question-answering tasks with a retrieval component. Extends the BaseChain class and implements the ConversationalRetrievalQAChainInput interface.

Example

const model = new ChatAnthropic({});

const text = fs.readFileSync("state_of_the_union.txt", "utf8");

const textSplitter = new RecursiveCharacterTextSplitter({ chunkSize: 1000 });
const docs = await textSplitter.createDocuments([text]);

const vectorStore = await HNSWLib.fromDocuments(docs, new OpenAIEmbeddings());

const chain = ConversationalRetrievalQAChain.fromLLM(
model,
vectorStore.asRetriever(),
);

const question = "What did the president say about Justice Breyer?";

const res = await chain.call({ question, chat_history: "" });
console.log(res);

const chatHistory = `${question}\n${res.text}`;
const followUpRes = await chain.call({
question: "Was that nice?",
chat_history: chatHistory,
});
console.log(followUpRes);

Hierarchy

Implements

Constructors

Properties

chatHistoryKey: string = "chat_history"
combineDocumentsChain: BaseChain<ChainValues, ChainValues>
inputKey: string = "question"
questionGeneratorChain: LLMChain<string, LLMType>
retriever: BaseRetriever
returnSourceDocuments: boolean = false
verbose: boolean

Whether to print out response text.

callbacks?: Callbacks
memory?: BaseMemory
metadata?: Record<string, unknown>
tags?: string[]

Accessors

  • get inputKeys(): string[]
  • Returns string[]

  • get outputKeys(): string[]
  • Returns string[]

Methods

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

    Wraps _call and handles memory.

    Parameters

    Returns Promise<ChainValues>

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

    Parameters

    Returns Promise<ChainValues>

    Promise that resolves with the output of the chain run.

  • Create a new runnable sequence that runs each individual runnable in series, piping the output of one runnable into another runnable or runnable-like.

    Type Parameters

    • NewRunOutput

    Parameters

    • coerceable: RunnableLike<ChainValues, NewRunOutput>

      A runnable, function, or object whose values are functions or runnables.

    Returns RunnableSequence<ChainValues, Exclude<NewRunOutput, Error>>

    A new runnable sequence.

  • Parameters

    Returns Promise<string>

  • Stream output in chunks.

    Parameters

    Returns Promise<IterableReadableStream<ChainValues>>

    A readable stream that is also an iterable.

  • Stream all output from a runnable, as reported to the callback system. This includes all inner runs of LLMs, Retrievers, Tools, etc. Output is streamed as Log objects, which include a list of jsonpatch ops that describe how the state of the run has changed in each step, and the final state of the run. The jsonpatch ops can be applied in order to construct state.

    Parameters

    Returns AsyncGenerator<RunLogPatch, any, unknown>

  • Default implementation of transform, which buffers input and then calls stream. Subclasses should override this method if they can start producing output while input is still being generated.

    Parameters

    Returns AsyncGenerator<ChainValues, any, unknown>

  • Static method to convert the chat history input into a formatted string.

    Parameters

    • chatHistory: string | BaseMessage[] | string[][]

      Chat history input which can be a string, an array of BaseMessage instances, or an array of string arrays.

    Returns string

    A formatted string representing the chat history.

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