Class BasePromptTemplate<RunInput, RunOutput, PartialVariableName>Abstract

Base class for prompt templates. Exposes a format method that returns a string prompt given a set of input values.

Type Parameters

Hierarchy

Implements

Constructors

Properties

PromptValueReturnType: RunOutput
inputVariables: Extract<keyof RunInput, string>[]

A list of variable names the prompt template expects

partialVariables: PartialValues<PartialVariableName>

Partial variables

name?: string
outputParser?: BaseOutputParser<unknown>

How to parse the output of calling an LLM on this formatted prompt

Methods

  • Format the prompt given the input values.

    Parameters

    Returns Promise<string>

    A formatted prompt string.

    Example

    prompt.format({ foo: "bar" });
    
  • Invokes the prompt template with the given input and options.

    Parameters

    • input: RunInput

      The input to invoke the prompt template with.

    • Optional options: BaseCallbackConfig

      Optional configuration for the callback.

    Returns Promise<RunOutput>

    A Promise that resolves to the output of the prompt template.

  • Merges partial variables and user variables.

    Parameters

    Returns Promise<InputValues<PartialVariableName | Extract<keyof RunInput, string>>>

    A Promise that resolves to an object containing the merged variables.

  • 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<RunOutput, NewRunOutput>

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

    Returns Runnable<RunInput, Exclude<NewRunOutput, Error>, RunnableConfig>

    A new runnable sequence.

  • 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

    • generator: AsyncGenerator<RunInput, any, unknown>
    • options: Partial<RunnableConfig>

    Returns AsyncGenerator<RunOutput, 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<RunInput, RunOutput, RunnableConfig>

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