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

constructor

Properties

chatHistoryKey combineDocumentsChain inputKey questionGeneratorChain retriever returnGeneratedQuestion returnSourceDocuments verbose callbacks? memory? metadata? name? tags?

Accessors

inputKeys outputKeys

Methods

apply assign batch bind call getName invoke map pick pipe prepOutputs run serialize stream streamLog toJSON toJSONNotImplemented transform withConfig withFallbacks withListeners withRetry deserialize fromLLM getChatHistoryString isRunnable

Constructors

constructor

Properties

chatHistoryKey

chatHistoryKey: string = "chat_history"

combineDocumentsChain

combineDocumentsChain: BaseChain<ChainValues, ChainValues>

inputKey

inputKey: string = "question"

questionGeneratorChain

questionGeneratorChain: LLMChain<string, LLMType>

retriever

retriever: BaseRetrieverInterface

returnGeneratedQuestion

returnGeneratedQuestion: boolean = false

returnSourceDocuments

returnSourceDocuments: boolean = false

verbose

verbose: boolean

Whether to print out response text.

Optional callbacks

callbacks?: Callbacks

Optional memory

memory?: BaseMemory

Optional metadata

metadata?: Record<string, unknown>

Optional name

name?: string

Optional tags

tags?: string[]

Accessors

inputKeys

outputKeys

Methods

apply

assign

  • Assigns new fields to the dict output of this runnable. Returns a new runnable.

    Parameters

    • mapping: RunnableMapLike<Record<string, unknown>, Record<string, unknown>>

    Returns RunnableSequence<any, any>

batch

  • Default implementation of batch, which calls invoke N times. Subclasses should override this method if they can batch more efficiently.

    Parameters

    • inputs: ChainValues[]

      Array of inputs to each batch call.

    • Optional options: Partial<RunnableConfig> | Partial<RunnableConfig>[]

      Either a single call options object to apply to each batch call or an array for each call.

    • Optional batchOptions: RunnableBatchOptions & {
          returnExceptions?: false;
      }

    Returns Promise<ChainValues[]>

    An array of RunOutputs, or mixed RunOutputs and errors if batchOptions.returnExceptions is set

  • Parameters

    Returns Promise<(Error | ChainValues)[]>

  • Parameters

    Returns Promise<(Error | ChainValues)[]>

bind

call

  • Parameters

    • values: ChainValues & {
          signal?: AbortSignal;
          timeout?: number;
      }
    • Optional config: RunnableConfig | Callbacks
    • 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.

getName

  • Parameters

    • Optional suffix: string

    Returns string

invoke

map

pick

  • Pick keys from the dict output of this runnable. Returns a new runnable.

    Parameters

    • keys: string | string[]

    Returns RunnableSequence<any, any>

pipe

  • 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.

prepOutputs

  • Parameters

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

    Returns Promise<Record<string, unknown>>

run

serialize

stream

  • Stream output in chunks.

    Parameters

    Returns Promise<IterableReadableStream<ChainValues>>

    A readable stream that is also an iterable.

streamLog

  • 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

    • input: ChainValues
    • Optional options: Partial<RunnableConfig>
    • Optional streamOptions: Omit<LogStreamCallbackHandlerInput, "autoClose">

    Returns AsyncGenerator<RunLogPatch, any, unknown>

toJSON

toJSONNotImplemented

transform

  • 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>

withConfig

withFallbacks

withListeners

  • Bind lifecycle listeners to a Runnable, returning a new Runnable. The Run object contains information about the run, including its id, type, input, output, error, startTime, endTime, and any tags or metadata added to the run.

    Parameters

    • params: {
          onEnd?: ((run, config?) => void | Promise<void>);
          onError?: ((run, config?) => void | Promise<void>);
          onStart?: ((run, config?) => void | Promise<void>);
      }

      The object containing the callback functions.

      • Optional onEnd?: ((run, config?) => void | Promise<void>)
          • (run, config?): void | Promise<void>

          • Called after the runnable finishes running, with the Run object.

            Parameters

            Returns void | Promise<void>

      • Optional onError?: ((run, config?) => void | Promise<void>)
          • (run, config?): void | Promise<void>

          • Called if the runnable throws an error, with the Run object.

            Parameters

            Returns void | Promise<void>

      • Optional onStart?: ((run, config?) => void | Promise<void>)
          • (run, config?): void | Promise<void>

          • Called before the runnable starts running, with the Run object.

            Parameters

            Returns void | Promise<void>

    Returns Runnable<ChainValues, ChainValues, RunnableConfig>

withRetry

Static deserialize

Static fromLLM

Static getChatHistoryString

  • 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.

Static isRunnable

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