LangGraph.js API Reference
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    Class StateGraph<SD, S, U, N, I, O, C, NodeReturnType, InterruptType, WriterType>

    A graph whose nodes communicate by reading and writing to a shared state. Each node takes a defined State as input and returns a Partial<State>.

    Each state key can optionally be annotated with a reducer function that will be used to aggregate the values of that key received from multiple nodes. The signature of a reducer function is (left: Value, right: UpdateValue) => Value.

    See Annotation for more on defining state.

    After adding nodes and edges to your graph, you must call .compile() on it before you can use it.

    import {
      type BaseMessage,
      AIMessage,
      HumanMessage,
    } from "@langchain/core/messages";
    import { StateGraph, Annotation } from "@langchain/langgraph";

    // Define a state with a single key named "messages" that will
    // combine a returned BaseMessage or arrays of BaseMessages
    const StateAnnotation = Annotation.Root({
      sentiment: Annotation<string>,
      messages: Annotation<BaseMessage[]>({
        reducer: (left: BaseMessage[], right: BaseMessage | BaseMessage[]) => {
          if (Array.isArray(right)) {
            return left.concat(right);
          }
          return left.concat([right]);
        },
        default: () => [],
      }),
    });

    const graphBuilder = new StateGraph(StateAnnotation);

    // A node in the graph that returns an object with a "messages" key
    // will update the state by combining the existing value with the returned one.
    const myNode = (state: typeof StateAnnotation.State) => {
      return {
        messages: [new AIMessage("Some new response")],
        sentiment: "positive",
      };
    };

    const graph = graphBuilder
      .addNode("myNode", myNode)
      .addEdge("__start__", "myNode")
      .addEdge("myNode", "__end__")
      .compile();

    await graph.invoke({ messages: [new HumanMessage("how are you?")] });

    // {
    //   messages: [HumanMessage("how are you?"), AIMessage("Some new response")],
    //   sentiment: "positive",
    // }

    Type Parameters

    Hierarchy (View Summary)

    • Graph<N, S, U, StateGraphNodeSpec<S, U>, ToStateDefinition<C>>
      • StateGraph
    Index

    Constructors

    constructor

    Properties

    branches channels compiled edges entryPoint? Node nodes waitingEdges

    Accessors

    allEdges

    Methods

    _addSchema addConditionalEdges addEdge addNode addSequence compile validate warnIfCompiled

    Deprecated

    setEntryPoint setFinishPoint

    Constructors

    Properties

    branches: Record<string, Record<string, Branch<RunInput, N, any>>>
    channels: Record<string, BaseChannel>
    compiled: boolean
    edges: Set<["__start__" | N, "__end__" | N]>
    entryPoint?: string
    Node: StrictNodeAction<S, U, C, N, InterruptType, WriterType>
    nodes: Record<N, NodeSpecType>
    waitingEdges: Set<[N[], N]>

    Accessors

    • get allEdges(): Set<[string, string]>

      Returns Set<[string, string]>

    Methods

    _addSchema

    • _addSchema(stateDefinition: SDZod): void

      Parameters

      • stateDefinition: SDZod

      Returns void

    • Parameters

      Returns this

    • Parameters

      • source: N
      • path: RunnableLike$1<
            S,
            BranchPathReturnValue,
            LangGraphRunnableConfig<StateType<ToStateDefinition<C>>>,
        >
      • OptionalpathMap: Record<string, "__end__" | N> | ("__end__" | N)[]

      Returns this

    • Parameters

      • startKey: "__start__" | N | N[]
      • endKey: "__end__" | N

      Returns this

    • Type Parameters

      • K extends string
      • NodeInput = S
      • NodeOutput = U

      Parameters

      Returns StateGraph<
          SD,
          S,
          U,
          N
          | K,
          I,
          O,
          C,
          MergeReturnType<NodeReturnType, { [key in string]: NodeOutput }>,
      >

    • Type Parameters

      Parameters

      Returns StateGraph<
          SD,
          S,
          U,
          N
          | K,
          I,
          O,
          C,
          MergeReturnType<
              NodeReturnType,
              {
                  [key in string
                  | number
                  | symbol]: NodeMap[key] extends NodeAction<
                      S,
                      U,
                      C,
                      InterruptType,
                      WriterType,
                  >
                      ? U
                      : never
              },
          >,
      >

    • Parameters

      • Optional__namedParameters: {
            cache?: BaseCache<unknown>;
            checkpointer?: boolean | BaseCheckpointSaver<number>;
            description?: string;
            interruptAfter?: "*" | N[];
            interruptBefore?: "*" | N[];
            name?: string;
            store?: BaseStore;
        }

      Returns CompiledStateGraph<
          { [K in string
          | number
          | symbol]: S[K] },
          { [K in string | number | symbol]: U[K] },
          N,
          I,
          O,
          C,
          NodeReturnType,
          InterruptType,
          WriterType,
      >

    • Parameters

      • Optionalinterrupt: string[]

      Returns void

    • Parameters

      • message: string

      Returns void

    Deprecated

    • Parameters

      • key: N

      Returns this

      use addEdge(START, key) instead

    • Parameters

      • key: N

      Returns this

      use addEdge(key, END) instead

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    Deprecated