Class RunnableWithMessageHistory<RunInput, RunOutput>

Wraps a LCEL chain and manages history. It appends input messages and chain outputs as history, and adds the current history messages to the chain input.

Example

// yarn add @langchain/anthropic @langchain/community @upstash/redis

import {
ChatPromptTemplate,
MessagesPlaceholder,
} from "@langchain/core/prompts";
import { ChatAnthropic } from "@langchain/anthropic";
import { UpstashRedisChatMessageHistory } from "@langchain/community/stores/message/upstash_redis";
// For demos, you can also use an in-memory store:
// import { ChatMessageHistory } from "langchain/stores/message/in_memory";

const prompt = ChatPromptTemplate.fromMessages([
["system", "You're an assistant who's good at {ability}"],
new MessagesPlaceholder("history"),
["human", "{question}"],
]);

const chain = prompt.pipe(new ChatAnthropic({}));

const chainWithHistory = new RunnableWithMessageHistory({
runnable: chain,
getMessageHistory: (sessionId) =>
new UpstashRedisChatMessageHistory({
sessionId,
config: {
url: process.env.UPSTASH_REDIS_REST_URL!,
token: process.env.UPSTASH_REDIS_REST_TOKEN!,
},
}),
inputMessagesKey: "question",
historyMessagesKey: "history",
});

const result = await chainWithHistory.invoke(
{
ability: "math",
question: "What does cosine mean?",
},
{
configurable: {
sessionId: "some_string_identifying_a_user",
},
}
);

const result2 = await chainWithHistory.invoke(
{
ability: "math",
question: "What's its inverse?",
},
{
configurable: {
sessionId: "some_string_identifying_a_user",
},
}
);

Type Parameters

  • RunInput

  • RunOutput

Hierarchy

Constructors

Properties

bound: Runnable<RunInput, RunOutput, RunnableConfig>
getMessageHistory: GetSessionHistoryCallable
runnable: Runnable<RunInput, RunOutput, RunnableConfig>
configFactories?: ((config) => RunnableConfig | Promise<RunnableConfig>)[]

Type declaration

historyMessagesKey?: string
inputMessagesKey?: string
name?: string
outputMessagesKey?: string
kwargs?: Partial<RunnableConfig>

Methods

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

    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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