Class SequentialChain

Chain where the outputs of one chain feed directly into next.

Example

const promptTemplate = new PromptTemplate({
  template: `You are a playwright. Given the title of play and the era it is set in, it is your job to write a synopsis for that title.
Title: {title}
Era: {era}
Playwright: This is a synopsis for the above play:`,
  inputVariables: ["title", "era"],
});

const reviewPromptTemplate = new PromptTemplate({
  template: `You are a play critic from the New York Times. Given the synopsis of play, it is your job to write a review for that play.
  
    Play Synopsis:
    {synopsis}
    Review from a New York Times play critic of the above play:`,
  inputVariables: ["synopsis"],
});

const overallChain = new SequentialChain({
  chains: [
    new LLMChain({
      llm: new ChatOpenAI({ temperature: 0 }),
      prompt: promptTemplate,
      outputKey: "synopsis",
    }),
    new LLMChain({
      llm: new OpenAI({ temperature: 0 }),
      prompt: reviewPromptTemplate,
      outputKey: "review",
    }),
  ],
  inputVariables: ["era", "title"],
  outputVariables: ["synopsis", "review"],
  verbose: true,
});

const chainExecutionResult = await overallChain.call({
  title: "Tragedy at sunset on the beach",
  era: "Victorian England",
});
console.log(chainExecutionResult);

Deprecated

Switch to expression language. Will be removed in 0.2.0

Hierarchy

Implements

Constructors

constructor

Properties

chains inputVariables outputVariables verbose callbacks? memory? metadata? name? returnAll? 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 isRunnable

Constructors

constructor

Properties

chains

chains: BaseChain<ChainValues, ChainValues>[]

Array of chains to run as a sequence. The chains are run in order they appear in the array.

inputVariables

inputVariables: string[]

Defines which variables should be passed as initial input to the first chain.

outputVariables

outputVariables: string[]

Which variables should be returned as a result of executing the chain. If not specified, output of the last of the chains is used.

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 returnAll

returnAll?: boolean

Whether or not to return all intermediate outputs and variables (excluding initial input variables).

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 isRunnable

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