Class HandlebarsPromptTemplate<RunInput>

constructor

• new HandlebarsPromptTemplate<RunInput>(input): HandlebarsPromptTemplate<RunInput>

• Type Parameters

  • RunInput extends InputValues = any

  Parameters

  • input: CustomFormatPromptTemplateInput<RunInput>

  Returns HandlebarsPromptTemplate<RunInput>

PromptValueReturnType

inputVariables

partialVariables

renderer

template

templateFormat

validateTemplate

Optional name

Optional outputParser

Optional templateValidator

assign

• assign(mapping): Runnable<any, any, RunnableConfig>

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

  Parameters

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

  Returns Runnable<any, any, RunnableConfig>

batch

• batch(inputs, options?, batchOptions?): Promise<StringPromptValueInterface[]>

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

  Parameters

  • inputs: RunInput[]

    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<StringPromptValueInterface[]>

  An array of RunOutputs, or mixed RunOutputs and errors if batchOptions.returnExceptions is set
• batch(inputs, options?, batchOptions?): Promise<(StringPromptValueInterface | Error)[]>

• Parameters

  • inputs: RunInput[]

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

  • Optional batchOptions: RunnableBatchOptions & {
        returnExceptions: true;
    }

  Returns Promise<(StringPromptValueInterface | Error)[]>

• batch(inputs, options?, batchOptions?): Promise<(StringPromptValueInterface | Error)[]>

• Parameters

  • inputs: RunInput[]

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

  • Optional batchOptions: RunnableBatchOptions

  Returns Promise<(StringPromptValueInterface | Error)[]>

bind

• bind(kwargs): Runnable<RunInput, StringPromptValueInterface, RunnableConfig>

• Bind arguments to a Runnable, returning a new Runnable.

  Parameters

  • kwargs: Partial<RunnableConfig>

  Returns Runnable<RunInput, StringPromptValueInterface, RunnableConfig>

  A new RunnableBinding that, when invoked, will apply the bound args.

format

• format(values): Promise<string>

• Formats the prompt template with the provided values.

  Parameters

  • values: TypedPromptInputValues<RunInput>

    The values to be used to format the prompt template.

  Returns Promise<string>

  A promise that resolves to a string which is the formatted prompt.

formatPromptValue

• formatPromptValue(values): Promise<StringPromptValueInterface>

• Formats the prompt given the input values and returns a formatted prompt value.

  Parameters

  • values: TypedPromptInputValues<RunInput>

    The input values to format the prompt.

  Returns Promise<StringPromptValueInterface>

  A Promise that resolves to a formatted prompt value.

getName

• getName(suffix?): string

• Parameters

  • Optional suffix: string

  Returns string

invoke

• invoke(input, options?): Promise<StringPromptValueInterface>

• 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<StringPromptValueInterface>

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

map

• map(): Runnable<RunInput[], StringPromptValueInterface[], RunnableConfig>

• Return a new Runnable that maps a list of inputs to a list of outputs, by calling invoke() with each input.

  Returns Runnable<RunInput[], StringPromptValueInterface[], RunnableConfig>

mergePartialAndUserVariables

• mergePartialAndUserVariables(userVariables): Promise<InputValues<any>>

• Merges partial variables and user variables.

  Parameters

  • userVariables: TypedPromptInputValues<RunInput>

    The user variables to merge with the partial variables.

  Returns Promise<InputValues<any>>

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

partial

• partial<NewPartialVariableName>(values): Promise<PromptTemplate<InputValues<Exclude<Extract<keyof RunInput, string>, NewPartialVariableName>>, any>>

• Partially applies values to the prompt template.

  Type Parameters

  • NewPartialVariableName extends string

  Parameters

  • values: PartialValues<NewPartialVariableName>

    The values to be partially applied to the prompt template.

  Returns Promise<PromptTemplate<InputValues<Exclude<Extract<keyof RunInput, string>, NewPartialVariableName>>, any>>

  A new instance of PromptTemplate with the partially applied values.

pick

• pick(keys): Runnable<any, any, RunnableConfig>

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

  Parameters

  • keys: string | string[]

  Returns Runnable<any, any, RunnableConfig>

pipe

• pipe<NewRunOutput>(coerceable): Runnable<RunInput, Exclude<NewRunOutput, Error>, RunnableConfig>

• 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<StringPromptValueInterface, NewRunOutput>

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

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

  A new runnable sequence.

serialize

• serialize(): SerializedPromptTemplate

• Return a json-like object representing this prompt template.

  Returns SerializedPromptTemplate

  Deprecated

stream

• stream(input, options?): Promise<IterableReadableStream<StringPromptValueInterface>>

• Stream output in chunks.

  Parameters

  • input: RunInput

  • Optional options: Partial<RunnableConfig>

  Returns Promise<IterableReadableStream<StringPromptValueInterface>>

  A readable stream that is also an iterable.

streamLog

• streamLog(input, options?, streamOptions?): AsyncGenerator<RunLogPatch, any, unknown>

• 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: RunInput

  • Optional options: Partial<RunnableConfig>

  • Optional streamOptions: Omit<LogStreamCallbackHandlerInput, "autoClose">

  Returns AsyncGenerator<RunLogPatch, any, unknown>

toJSON

• toJSON(): Serialized

• Returns Serialized

toJSONNotImplemented

• toJSONNotImplemented(): SerializedNotImplemented

• Returns SerializedNotImplemented

transform

• transform(generator, options): AsyncGenerator<StringPromptValueInterface, 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<StringPromptValueInterface, any, unknown>

withConfig

• withConfig(config): RunnableBinding<RunInput, StringPromptValueInterface, RunnableConfig>

• Bind config to a Runnable, returning a new Runnable.

  Parameters

  • config: RunnableConfig

    New configuration parameters to attach to the new runnable.

  Returns RunnableBinding<RunInput, StringPromptValueInterface, RunnableConfig>

  A new RunnableBinding with a config matching what's passed.

withFallbacks

• withFallbacks(fields): RunnableWithFallbacks<RunInput, StringPromptValueInterface>

• Create a new runnable from the current one that will try invoking other passed fallback runnables if the initial invocation fails.

  Parameters

  • fields: {
        fallbacks: Runnable<RunInput, StringPromptValueInterface, RunnableConfig>[];
    }

    • fallbacks: Runnable<RunInput, StringPromptValueInterface, RunnableConfig>[]

      Other runnables to call if the runnable errors.

  Returns RunnableWithFallbacks<RunInput, StringPromptValueInterface>

  A new RunnableWithFallbacks.

withListeners

• withListeners(params): Runnable<RunInput, StringPromptValueInterface, RunnableConfig>

• 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

          • run: Run

          • Optional config: RunnableConfig

          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

          • run: Run

          • Optional config: RunnableConfig

          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

          • run: Run

          • Optional config: RunnableConfig

          Returns void | Promise<void>

  Returns Runnable<RunInput, StringPromptValueInterface, RunnableConfig>

withRetry

• withRetry(fields?): RunnableRetry<RunInput, StringPromptValueInterface, RunnableConfig>

• Add retry logic to an existing runnable.

  Parameters

  • Optional fields: {
        onFailedAttempt?: RunnableRetryFailedAttemptHandler;
        stopAfterAttempt?: number;
    }

    • Optional onFailedAttempt?: RunnableRetryFailedAttemptHandler

    • Optional stopAfterAttempt?: number

  Returns RunnableRetry<RunInput, StringPromptValueInterface, RunnableConfig>

  A new RunnableRetry that, when invoked, will retry according to the parameters.

Static deserialize

• deserialize(data): Promise<PromptTemplate<any, any>>

• Parameters

  • data: SerializedPromptTemplate

  Returns Promise<PromptTemplate<any, any>>

  ⚠️ Deprecated ⚠️

  Load a prompt template from a json-like object describing it.

  This feature is deprecated and will be removed in the future.

  It is not recommended for use.

  Remarks

  Deserializing needs to be async because templates (e.g. FewShotPromptTemplate) can reference remote resources that we read asynchronously with a web request.

Static fromExamples

• fromExamples(examples, suffix, inputVariables, exampleSeparator?, prefix?): PromptTemplate<any, any>

• Take examples in list format with prefix and suffix to create a prompt.

  Intended to be used a a way to dynamically create a prompt from examples.

  Parameters

  • examples: string[]

    List of examples to use in the prompt.

  • suffix: string

    String to go after the list of examples. Should generally set up the user's input.

  • inputVariables: string[]

    A list of variable names the final prompt template will expect

  • Optional exampleSeparator: string

    The separator to use in between examples

  • Optional prefix: string

    String that should go before any examples. Generally includes examples.

  Returns PromptTemplate<any, any>

  The final prompt template generated.

Static isRunnable

• isRunnable(thing): thing is Runnable<any, any, RunnableConfig>

• Parameters

  • thing: any

  Returns thing is Runnable<any, any, RunnableConfig>