langchain.js
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    Class MomentoChatMessageHistory

    A class that stores chat message history using Momento Cache. It interacts with a Momento cache client to perform operations like fetching, adding, and deleting messages.

    const chatHistory = await MomentoChatMessageHistory.fromProps({
      client: new CacheClient({
        configuration: Configurations.Laptop.v1(),
        credentialProvider: CredentialProvider.fromEnvironmentVariable({
          environmentVariableName: "MOMENTO_API_KEY",
        }),
        defaultTtlSeconds: 60 * 60 * 24,
      }),
      cacheName: "langchain",
      sessionId: new Date().toISOString(),
      sessionTtl: 300,
    });

    const messages = await chatHistory.getMessages();
    console.log({ messages });

    Hierarchy (View Summary)

    Index

    Properties

    lc_namespace

    Methods

    addMessage clear getMessages fromProps

    Properties

    lc_namespace: string[] = ...

    Methods

    • Adds a message to the cache.

      Parameters

      • message: BaseMessage

        The BaseMessage instance to add to the cache.

      Returns Promise<void>

      A Promise that resolves when the message has been added.

    • Deletes all messages from the cache.

      Returns Promise<void>

      A Promise that resolves when all messages have been deleted.

    • Fetches messages from the cache.

      Returns Promise<BaseMessage[]>

      A Promise that resolves to an array of BaseMessage instances.

    • Create a new chat message history backed by Momento.

      Parameters

      • props: MomentoChatMessageHistoryProps

        The settings to instantiate the Momento chat message history.

        The settings to instantiate the Momento chat message history.

        • cacheName: string

          The name of the cache to use to store the data.

        • client: ICacheClient

          The Momento cache client.

        • OptionalensureCacheExists?: true

          If true, ensure that the cache exists before returning. If false, the cache is not checked for existence. Defaults to true.

        • sessionId: string

          The session ID to use to store the data.

        • OptionalsessionTtl?: number

          The time to live for the cache items in seconds. If not specified, the cache client default is used.

      Returns Promise<MomentoChatMessageHistory>

      A new chat message history backed by Momento.

      If props.sessionTtl is not strictly positive.

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