Class RetrievalQAChain

Class representing a chain for performing question-answering tasks with a retrieval component.

Example

// Initialize the OpenAI model and the remote retriever with the specified configuration
const model = new ChatOpenAI({});
const retriever = new RemoteLangChainRetriever({
url: "http://example.com/api",
auth: { bearer: "foo" },
inputKey: "message",
responseKey: "response",
});

// Create a RetrievalQAChain using the model and retriever
const chain = RetrievalQAChain.fromLLM(model, retriever);

// Execute the chain with a query and log the result
const res = await chain.call({
query: "What did the president say about Justice Breyer?",
});
console.log({ res });

Hierarchy

Implements

Constructors

Properties

combineDocumentsChain: BaseChain<ChainValues, ChainValues>
inputKey: string = "query"
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

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

    Returns Promise<Record<string, unknown>>

  • 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>

  • 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, BaseCallbackConfig>

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