Improve return type of useNodesdata

.changeset/old-laws-melt.md

@@ -0,0 +1,8 @@
+---
+'@xyflow/react': patch
+'@xyflow/svelte': patch
+'@xyflow/system': patch
+---
+
+Improve return type of useNodesData. Now you can narrow down the data type by checking the node type.  
+

examples/react/src/examples/UseNodesData/TextNode.tsx

@@ -1,7 +1,8 @@
 import { memo, useState } from 'react';
 import { Position, NodeProps, Handle, useReactFlow } from '@xyflow/react';
+import type { TextNode } from '.';
 
-function TextNode({ id, data }: NodeProps) {
+function TextNode({ id, data }: NodeProps<TextNode>) {
   const { updateNodeData } = useReactFlow();
   const [text, setText] = useState(data.text);
   const updateText = (text: string) => {

examples/react/src/examples/UseNodesData/UppercaseNode.tsx

@@ -1,18 +1,18 @@
 import { memo, useEffect } from 'react';
 import { Position, NodeProps, useReactFlow, Handle, useNodeConnections, useNodesData } from '@xyflow/react';
-import { isTextNode, type TextNode, type MyNode } from '.';
+import { isTextNode, type TextNode, type MyNode, type UppercaseNode } from '.';
 
-function UppercaseNode({ id }: NodeProps) {
+function UppercaseNode({ id }: NodeProps<UppercaseNode>) {
   const { updateNodeData } = useReactFlow();
   const connections = useNodeConnections({
     handleType: 'target',
   });
   const nodesData = useNodesData<MyNode>(connections[0]?.source);
-  const textNode = isTextNode(nodesData) ? nodesData : null;
 
   useEffect(() => {
-    updateNodeData(id, { text: textNode?.data.text.toUpperCase() });
-  }, [textNode]);
+    const text = nodesData?.type === 'text' ? nodesData?.data.text.toUpperCase() : undefined;
+    updateNodeData(id, { text });
+  }, [nodesData]);
 
   return (
     <div style={{ background: '#eee', color: '#222', padding: 10, fontSize: 12, borderRadius: 10 }}>

examples/svelte/src/routes/examples/usenodesdata/UppercaseNode.svelte

@@ -8,22 +8,21 @@
 		type Node,
 		type NodeProps
 	} from '@xyflow/svelte';
-	import { isTextNode, type MyNode } from './+page.svelte';
+	import { type MyNode } from './+page.svelte';
 
 	let { id }: NodeProps<Node<{ text: string }>> = $props();
 
 	const { updateNodeData } = useSvelteFlow();
 	const connections = useNodeConnections({
-		id: id,
 		handleType: 'target'
 	});
 
-	let nodeData = $derived(useNodesData<MyNode>(connections.current[0]?.source));
-	let textNodeData = $derived(isTextNode(nodeData.current) ? nodeData.current.data.text : null);
+	let nodesData = $derived(useNodesData<MyNode>(connections.current[0]?.source));
 
 	$effect.pre(() => {
-		const input = textNodeData?.toUpperCase() ?? '';
-		updateNodeData(id, { text: input });
+		const text =
+			nodesData.current?.type === 'text' ? nodesData.current?.data.text.toUpperCase() : undefined;
+		updateNodeData(id, { text });
 	});
 </script>
 

packages/react/src/hooks/useNodesData.ts

@@ -1,5 +1,5 @@
 import { useCallback } from 'react';
-import { shallowNodeData } from '@xyflow/system';
+import { DistributivePick, shallowNodeData } from '@xyflow/system';
 
 import { useStore } from '../hooks/useStore';
 import type { Node } from '../types';
@@ -25,11 +25,11 @@ import type { Node } from '../types';
 export function useNodesData<NodeType extends Node = Node>(
   /** The id of the node to get the data from. */
   nodeId: string
-): Pick<NodeType, 'id' | 'type' | 'data'> | null;
+): DistributivePick<NodeType, 'id' | 'type' | 'data'> | null;
 export function useNodesData<NodeType extends Node = Node>(
   /** The ids of the nodes to get the data from. */
   nodeIds: string[]
-): Pick<NodeType, 'id' | 'type' | 'data'>[];
+): DistributivePick<NodeType, 'id' | 'type' | 'data'>[];
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 export function useNodesData(nodeIds: any): any {
   const nodesData = useStore(

packages/svelte/src/lib/hooks/useNodesData.svelte.ts

@@ -1,4 +1,4 @@
-import { shallowNodeData } from '@xyflow/system';
+import { shallowNodeData, type DistributivePick } from '@xyflow/system';
 
 import type { Node } from '$lib/types';
 import { useStore } from '$lib/store';
@@ -12,10 +12,10 @@ import { useStore } from '$lib/store';
  */
 export function useNodesData<NodeType extends Node = Node>(
   nodeId: string
-): { current: Pick<NodeType, 'id' | 'data' | 'type'> | null };
+): { current: DistributivePick<NodeType, 'id' | 'data' | 'type'> | null };
 export function useNodesData<NodeType extends Node = Node>(
   nodeIds: string[]
-): { current: Pick<NodeType, 'id' | 'data' | 'type'>[] };
+): { current: DistributivePick<NodeType, 'id' | 'data' | 'type'>[] };
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 export function useNodesData(nodeIds: any): any {
   const { nodes, nodeLookup } = $derived(useStore());

packages/system/src/types/utils.ts

@@ -56,3 +56,10 @@ export type Transform = [number, number, number];
  * to represent an unbounded extent.
  */
 export type CoordinateExtent = [[number, number], [number, number]];
+
+/**
+ * Using Pick with a union type (e.g. `NodeType`) will merge every property type along all union members.
+ * See https://github.com/microsoft/TypeScript/issues/28339#issuecomment-463577347
+ * Note: Currently you are able to Pick properties that are not in the type without error.
+ */
+export type DistributivePick<T, K extends string> = T extends unknown ? { [P in Extract<keyof T, K>]: T[P] } : never;