How to define input/output schema for your graph¶
By default, StateGraph takes in a single schema and all nodes are expected to communicate with that schema. However, it is also possible to define explicit input and output schemas for a graph. This is helpful if you want to draw a distinction between input and output keys.
In this notebook we'll walk through an example of this. At a high level, in order to do this you simply have to pass in separate Annotation.Root({}) objets as { input: Annotation.Root({}), output: Annotation.Root({}) } when defining the graph. Let's see an example below!
import { Annotation, StateGraph } from "@langchain/langgraph";
const InputAnnotation = Annotation.Root({
question: Annotation<string>,
});
const OutputAnnotation = Annotation.Root({
answer: Annotation<string>,
});
const answerNode = (_state: typeof InputAnnotation.State) => {
return { answer: "bye" };
};
const graph = new StateGraph({
input: InputAnnotation,
output: OutputAnnotation,
})
.addNode("answerNode", answerNode)
.addEdge("__start__", "answerNode")
.compile();
await graph.invoke({
question: "hi",
});