Interface UseStreamOptions<StateType, Bag>

interface UseStreamOptions<StateType, Bag> {
    apiKey?: string;
    apiUrl?: string;
    assistantId: string;
    callerOptions?: AsyncCallerParams;
    client?: Client<DefaultValues, DefaultValues, unknown>;
    defaultHeaders?: Record<string, HeaderValue>;
    fetchStateHistory?: boolean | {
        limit: number;
    };
    initialValues?: null | StateType;
    messagesKey?: string;
    onCheckpointEvent?: ((data, options) => void);
    onCreated?: ((run) => void);
    onCustomEvent?: ((data, options) => void);
    onError?: ((error, run) => void);
    onFinish?: ((state, run) => void);
    onLangChainEvent?: ((data) => void);
    onMetadataEvent?: ((data) => void);
    onStop?: ((options) => void);
    onTaskEvent?: ((data, options) => void);
    onThreadId?: ((threadId) => void);
    onUpdateEvent?: ((data, options) => void);
    reconnectOnMount?: boolean | (() => RunMetadataStorage);
    threadId?: null | string;
}

Type Parameters

  • StateType extends Record<string, unknown> = Record<string, unknown>
  • Bag extends BagTemplate = BagTemplate

Properties

apiKey? apiUrl? assistantId callerOptions? client? defaultHeaders? fetchStateHistory? initialValues? messagesKey? onCheckpointEvent? onCreated? onCustomEvent? onError? onFinish? onLangChainEvent? onMetadataEvent? onStop? onTaskEvent? onThreadId? onUpdateEvent? reconnectOnMount? threadId?

Properties

Optional apiKey

apiKey?: string

The API key to use.

Optional apiUrl

apiUrl?: string

The URL of the API to use.

assistantId

assistantId: string

The ID of the assistant to use.

Optional callerOptions

callerOptions?: AsyncCallerParams

Custom call options, such as custom fetch implementation.

Optional client

client?: Client<DefaultValues, DefaultValues, unknown>

Client used to send requests.

Optional defaultHeaders

defaultHeaders?: Record<string, HeaderValue>

Default headers to send with requests.

Optional fetchStateHistory

fetchStateHistory?: boolean | {
    limit: number;
}

Whether to fetch the history of the thread. If true, the history will be fetched from the server. Defaults to 10 entries. If false, only the last state will be fetched from the server.

Type declaration

  • limit: number

Default

true

Optional initialValues

initialValues?: null | StateType

Initial values to display immediately when loading a thread. Useful for displaying cached thread data while official history loads. These values will be replaced when official thread data is fetched.

Note: UI components from initialValues will render immediately if they're predefined in LoadExternalComponent's components prop, providing instant cached UI display without server fetches.

Optional messagesKey

messagesKey?: string

Specify the key within the state that contains messages. Defaults to "messages".

Default

"messages"

Optional onCheckpointEvent

onCheckpointEvent?: ((data, options) => void)

Callback that is called when a checkpoints event is received.

Type declaration

    • (data, options): void

    • Parameters

      Returns void

Optional onCreated

onCreated?: ((run) => void)

Callback that is called when a new stream is created.

Type declaration

    • (run): void

    • Parameters

      • run: RunCallbackMeta

      Returns void

Optional onCustomEvent

onCustomEvent?: ((data, options) => void)

Callback that is called when a custom event is received.

Type declaration

    • (data, options): void

    • Parameters

      • data: GetCustomEventType<Bag>
      • options: {
            mutate: ((update) => void);
            namespace: undefined | string[];
        }
        • mutate: ((update) => void)
            • (update): void

            • Parameters

              Returns void

        • namespace: undefined | string[]

      Returns void

Optional onError

onError?: ((error, run) => void)

Callback that is called when an error occurs.

Type declaration

    • (error, run): void

    • Parameters

      • error: unknown
      • run: undefined | RunCallbackMeta

      Returns void

Optional onFinish

onFinish?: ((state, run) => void)

Callback that is called when the stream is finished.

Type declaration

    • (state, run): void

    • Parameters

      Returns void

Optional onLangChainEvent

onLangChainEvent?: ((data) => void)

Callback that is called when a LangChain event is received.

Type declaration

    • (data): void

    • Parameters

      • data: {
            data: unknown;
            event: string & {} | "on_chain_start" | "on_chain_end" | "on_chat_model_start" | "on_chat_model_stream" | "on_chat_model_end" | "on_chain_stream" | "on_tool_start" | "on_tool_stream" | "on_tool_end" | "on_prompt_start" | "on_prompt_stream" | "on_prompt_end" | "on_llm_start" | "on_llm_stream" | "on_llm_end" | "on_retriever_start" | "on_retriever_stream" | "on_retriever_end";
            metadata: Record<string, unknown>;
            name: string;
            parent_ids: string[];
            run_id: string;
            tags: string[];
        }
        • data: unknown
        • event: string & {} | "on_chain_start" | "on_chain_end" | "on_chat_model_start" | "on_chat_model_stream" | "on_chat_model_end" | "on_chain_stream" | "on_tool_start" | "on_tool_stream" | "on_tool_end" | "on_prompt_start" | "on_prompt_stream" | "on_prompt_end" | "on_llm_start" | "on_llm_stream" | "on_llm_end" | "on_retriever_start" | "on_retriever_stream" | "on_retriever_end"
        • metadata: Record<string, unknown>
        • name: string
        • parent_ids: string[]
        • run_id: string
        • tags: string[]

      Returns void

See

https://langchain-ai.github.io/langgraph/cloud/how-tos/stream_events/#stream-graph-in-events-mode for more details.

Optional onMetadataEvent

onMetadataEvent?: ((data) => void)

Callback that is called when a metadata event is received.

Type declaration

    • (data): void

    • Parameters

      • data: {
            run_id: string;
            thread_id: string;
        }
        • run_id: string
        • thread_id: string

      Returns void

Optional onStop

onStop?: ((options) => void)

Callback that is called when the stream is stopped by the user. Provides a mutate function to update the stream state immediately without requiring a server roundtrip.

Type declaration

    • (options): void

    • Parameters

      • options: {
            mutate: ((update) => void);
        }
        • mutate: ((update) => void)
            • (update): void

            • Parameters

              Returns void

      Returns void

Example

onStop: ({ mutate }) => {
  mutate((prev) => ({
    ...prev,
    ui: prev.ui?.map(component =>
      component.props.isLoading
        ? { ...component, props: { ...component.props, stopped: true, isLoading: false }}
        : component
    )
  }));
}

Optional onTaskEvent

onTaskEvent?: ((data, options) => void)

Callback that is called when a tasks event is received.

Type declaration

    • (data, options): void

    • Parameters

      • data: {
            error: string;
            id: string;
            interrupts: Interrupt<unknown>[];
            name: string;
        } | {
            id: string;
            input: StateType;
            interrupts: Interrupt<unknown>[];
            name: string;
            triggers: string[];
        } | {
            id: string;
            interrupts: Interrupt<unknown>[];
            name: string;
            result: [string, GetUpdateType<Bag, StateType>][];
        }
      • options: {
            namespace: undefined | string[];
        }
        • namespace: undefined | string[]

      Returns void

Optional onThreadId

onThreadId?: ((threadId) => void)

Callback that is called when the thread ID is updated (ie when a new thread is created).

Type declaration

    • (threadId): void

    • Parameters

      • threadId: string

      Returns void

Optional onUpdateEvent

onUpdateEvent?: ((data, options) => void)

Callback that is called when an update event is received.

Type declaration

    • (data, options): void

    • Parameters

      • data: {
            [node: string]: UpdateType;
        }
      • options: {
            mutate: ((update) => void);
            namespace: undefined | string[];
        }
        • mutate: ((update) => void)
            • (update): void

            • Parameters

              Returns void

        • namespace: undefined | string[]

      Returns void

Optional reconnectOnMount

reconnectOnMount?: boolean | (() => RunMetadataStorage)

Will reconnect the stream on mount

Type declaration

    • (): RunMetadataStorage

    • Returns RunMetadataStorage

Optional threadId

threadId?: null | string

The ID of the thread to fetch history and current values from.

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