Class ChatPromptTemplate<RunInput, PartialVariableName>

Class that represents a chat prompt. It extends the BaseChatPromptTemplate and uses an array of BaseMessagePromptTemplate instances to format a series of messages for a conversation.

Example

const message = SystemMessagePromptTemplate.fromTemplate("{text}");
const chatPrompt = ChatPromptTemplate.fromMessages([
["ai", "You are a helpful assistant."],
message,
]);
const formattedChatPrompt = await chatPrompt.invoke({
text: "Hello world!",
});

Type Parameters

  • RunInput extends InputValues = any

  • PartialVariableName extends string = any

Hierarchy

Implements

  • ChatPromptTemplateInput<RunInput, PartialVariableName>

Constructors

  • Type Parameters

    • RunInput extends InputValues = any

    • PartialVariableName extends string = any

    Parameters

    • input: ChatPromptTemplateInput<RunInput, PartialVariableName>

    Returns ChatPromptTemplate<RunInput, PartialVariableName>

Properties

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

A list of variable names the prompt template expects

partialVariables: PartialValues<PartialVariableName>

Partial variables

promptMessages: (BaseMessage | BaseMessagePromptTemplate<any, BaseMessage[]>)[]
validateTemplate: boolean
outputParser?: BaseOutputParser<unknown>

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

Methods

  • 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<BaseCallbackConfig> | Partial<BaseCallbackConfig>[]

      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<ChatPromptValue[]>

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

  • Parameters

    Returns Promise<(Error | ChatPromptValue)[]>

  • Parameters

    Returns Promise<(Error | ChatPromptValue)[]>

  • Format the prompt given the input values.

    Parameters

    • values: TypedPromptInputValues<RunInput>

      A dictionary of arguments to be passed to the prompt template.

    Returns Promise<string>

    A formatted prompt string.

    Example

    prompt.format({ foo: "bar" });
    
  • Format the prompt given the input values and return a formatted prompt value.

    Parameters

    • values: TypedPromptInputValues<RunInput>

    Returns Promise<ChatPromptValue>

    A formatted PromptValue.

  • 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<ChatPromptValue>

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

  • Merges partial variables and user variables.

    Parameters

    • userVariables: TypedPromptInputValues<RunInput>

      The user variables to merge with the partial variables.

    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<ChatPromptValue, NewRunOutput>

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

    Returns RunnableSequence<RunInput, Exclude<NewRunOutput, Error>>

    A new runnable sequence.

  • Stream output in chunks.

    Parameters

    Returns Promise<IterableReadableStream<ChatPromptValue>>

    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

    • input: RunInput
    • Optional options: Partial<BaseCallbackConfig>
    • Optional streamOptions: Omit<LogStreamCallbackHandlerInput, "autoClose">

    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<ChatPromptValue, 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, ChatPromptValue, BaseCallbackConfig>

  • Create a chat model-specific prompt from individual chat messages or message-like tuples.

    Type Parameters

    Parameters

    Returns ChatPromptTemplate<RunInput, any>

    A new ChatPromptTemplate

  • Load prompt template from a template f-string

    Type Parameters

    • RunInput extends InputValues = Symbol

    • T extends string = string

    Parameters

    • template: T

    Returns ChatPromptTemplate<RunInput extends Symbol
        ? ParamsFromFString<T>
        : RunInput, any>

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