Merge pull request #4725 from xyflow/feat/use-handle-connection

add `useNodeConnections`, deprecate `useHandleConnections`

packages/react/src/hooks/useHandleConnections.ts

@@ -22,6 +22,7 @@ type useHandleConnectionsParams = {
  * Hook to check if a <Handle /> is connected to another <Handle /> and get the connections.
  *
  * @public
+ * @deprecated Use `useNodeConnections` instead.
  * @param param.type - handle type 'source' or 'target'
  * @param param.nodeId - node id - if not provided, the node id from the NodeIdContext is used
  * @param param.id - the handle id (this is only needed if the node has multiple handles of the same type)
@@ -31,18 +32,22 @@ type useHandleConnectionsParams = {
  */
 export function useHandleConnections({
   type,
-  id = null,
+  id,
   nodeId,
   onConnect,
   onDisconnect,
 }: useHandleConnectionsParams): HandleConnection[] {
+  console.warn(
+    '[DEPRECATED] `useHandleConnections` is deprecated. Instead use `useNodeConnections` https://reactflow.dev/api-reference/hooks/useNodeConnections'
+  );
+
   const _nodeId = useNodeId();
   const currentNodeId = nodeId ?? _nodeId;
 
   const prevConnections = useRef<Map<string, HandleConnection> | null>(null);
 
   const connections = useStore(
-    (state) => state.connectionLookup.get(`${currentNodeId}-${type}-${id}`),
+    (state) => state.connectionLookup.get(`${currentNodeId}-${type}${id ? `-${id}` : ''}`),
     areConnectionMapsEqual
   );
 

packages/react/src/hooks/useNodeConnections.ts

@@ -0,0 +1,69 @@
+import { useEffect, useMemo, useRef } from 'react';
+import {
+  Connection,
+  NodeConnection,
+  HandleType,
+  areConnectionMapsEqual,
+  handleConnectionChange,
+  errorMessages,
+} from '@xyflow/system';
+
+import { useStore } from './useStore';
+import { useNodeId } from '../contexts/NodeIdContext';
+
+const error014 = errorMessages['error014']();
+
+type UseNodeConnectionsParams = {
+  type?: HandleType;
+  handleId?: string;
+  nodeId?: string;
+  onConnect?: (connections: Connection[]) => void;
+  onDisconnect?: (connections: Connection[]) => void;
+};
+
+/**
+ * Hook to retrieve all edges connected to a node. Can be filtered by handle type and id.
+ *
+ * @public
+ * @param param.nodeId - node id - optional if called inside a custom node
+ * @param param.type - filter by handle type 'source' or 'target'
+ * @param param.handleId - filter by handle id (this is only needed if the node has multiple handles of the same type)
+ * @param param.onConnect - gets called when a connection is established
+ * @param param.onDisconnect - gets called when a connection is removed
+ * @returns an array with connections
+ */
+export function useNodeConnections({
+  type,
+  handleId,
+  nodeId,
+  onConnect,
+  onDisconnect,
+}: UseNodeConnectionsParams = {}): NodeConnection[] {
+  const _nodeId = useNodeId();
+  const currentNodeId = nodeId ?? _nodeId;
+
+  if (!currentNodeId) {
+    throw new Error(error014);
+  }
+
+  const prevConnections = useRef<Map<string, NodeConnection> | null>(null);
+
+  const connections = useStore(
+    (state) =>
+      state.connectionLookup.get(`${currentNodeId}${type ? (handleId ? `-${type}-${handleId}` : `-${type}`) : ''}`),
+    areConnectionMapsEqual
+  );
+
+  useEffect(() => {
+    // @todo dicuss if onConnect/onDisconnect should be called when the component mounts/unmounts
+    if (prevConnections.current && prevConnections.current !== connections) {
+      const _connections = connections ?? new Map();
+      handleConnectionChange(prevConnections.current, _connections, onDisconnect);
+      handleConnectionChange(_connections, prevConnections.current, onConnect);
+    }
+
+    prevConnections.current = connections ?? new Map();
+  }, [connections, onConnect, onDisconnect]);
+
+  return useMemo(() => Array.from(connections?.values() ?? []), [connections]);
+}

packages/react/src/hooks/useReactFlow.ts

@@ -238,7 +238,14 @@ export function useReactFlow<NodeType extends Node = Node, EdgeType extends Edge
         Array.from(
           store
             .getState()
-            .connectionLookup.get(`${nodeId}-${type}-${id ?? null}`)
+            .connectionLookup.get(`${nodeId}-${type}${id ? `-${id}` : ''}`)
+            ?.values() ?? []
+        ),
+      getNodeConnections: ({ type, handleId, nodeId }) =>
+        Array.from(
+          store
+            .getState()
+            .connectionLookup.get(`${nodeId}${type ? (handleId ? `-${type}-${handleId}` : `-${type}`) : ''}`)
             ?.values() ?? []
         ),
     };

packages/react/src/index.ts

@@ -24,6 +24,7 @@ export { useOnViewportChange, type UseOnViewportChangeOptions } from './hooks/us
 export { useOnSelectionChange, type UseOnSelectionChangeOptions } from './hooks/useOnSelectionChange';
 export { useNodesInitialized, type UseNodesInitializedOptions } from './hooks/useNodesInitialized';
 export { useHandleConnections } from './hooks/useHandleConnections';
+export { useNodeConnections } from './hooks/useNodeConnections';
 export { useNodesData } from './hooks/useNodesData';
 export { useConnection } from './hooks/useConnection';
 export { useInternalNode } from './hooks/useInternalNode';

packages/react/src/types/instance.ts

@@ -1,5 +1,5 @@
 /* eslint-disable @typescript-eslint/no-namespace */
-import type { HandleConnection, HandleType, Rect, Viewport } from '@xyflow/system';
+import type { HandleConnection, HandleType, NodeConnection, Rect, Viewport } from '@xyflow/system';
 import type { Node, Edge, ViewportHelperFunctions, InternalNode } from '.';
 
 export type ReactFlowJsonObject<NodeType extends Node = Node, EdgeType extends Edge = Edge> = {
@@ -183,7 +183,7 @@ export type GeneralHelpers<NodeType extends Node = Node, EdgeType extends Edge =
   getNodesBounds: (nodes: (NodeType | InternalNode | string)[]) => Rect;
   /**
    * Gets all connections for a given handle belonging to a specific node.
-   *
+   * @deprecated
    * @param type - handle type 'source' or 'target'
    * @param id - the handle id (this is only needed if you have multiple handles of the same type, meaning you have to provide a unique id for each handle)
    * @param nodeId - the node id the handle belongs to
@@ -198,6 +198,23 @@ export type GeneralHelpers<NodeType extends Node = Node, EdgeType extends Edge =
     nodeId: string;
     id?: string | null;
   }) => HandleConnection[];
+  /**
+   * Gets all connections to a node. Can be filtered by handle type and id.
+   * @deprecated use `getNodeConnections` instead
+   * @param type - handle type 'source' or 'target'
+   * @param handleId - the handle id (this is only needed if you have multiple handles of the same type, meaning you have to provide a unique id for each handle)
+   * @param nodeId - the node id the handle belongs to
+   * @returns an array with handle connections
+   */
+  getNodeConnections: ({
+    type,
+    handleId,
+    nodeId,
+  }: {
+    type?: HandleType;
+    nodeId: string;
+    handleId?: string | null;
+  }) => NodeConnection[];
 };
 
 export type ReactFlowInstance<NodeType extends Node = Node, EdgeType extends Edge = Edge> = GeneralHelpers<

packages/svelte/src/lib/components/Handle/Handle.svelte

@@ -116,7 +116,7 @@
   $: if (onconnect || ondisconnect) {
     // connectionLookup is not reactive, so we use edges to get notified about updates
     $edges;
-    connections = $connectionLookup.get(`${nodeId}-${type}-${id || null}`);
+    connections = $connectionLookup.get(`${nodeId}-${type}${id ? `-${id}` : ''}`);
   }
 
   $: {

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

@@ -16,14 +16,19 @@ const initialConnections: HandleConnection[] = [];
  *  Hook to check if a <Handle /> is connected to another <Handle /> and get the connections.
  *
  * @public
+ * @deprecated Use `useNodeConnections` instead.
  * @param param.nodeId
  * @param param.type - handle type 'source' or 'target'
  * @param param.id - the handle id (this is only needed if the node has multiple handles of the same type)
  * @returns an array with connections
  */
-export function useHandleConnections({ type, nodeId, id = null }: useHandleConnectionsParams) {
+export function useHandleConnections({ type, nodeId, id }: useHandleConnectionsParams) {
   const { edges, connectionLookup } = useStore();
 
+  console.warn(
+    '[DEPRECATED] `useHandleConnections` is deprecated. Instead use `useNodeConnections` https://svelteflow.dev/api-reference/hooks/useNodeConnections'
+  );
+
   const _nodeId = getContext<string>('svelteflow__node_id');
   const currentNodeId = nodeId ?? _nodeId;
 
@@ -32,7 +37,7 @@ export function useHandleConnections({ type, nodeId, id = null }: useHandleConne
   return derived(
     [edges, connectionLookup],
     ([, connectionLookup], set) => {
-      const nextConnections = connectionLookup.get(`${currentNodeId}-${type}-${id || null}`);
+      const nextConnections = connectionLookup.get(`${currentNodeId}-${type}${id ? `-${id}` : ''}`);
 
       if (!areConnectionMapsEqual(nextConnections, prevConnections)) {
         prevConnections = nextConnections;

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

@@ -0,0 +1,62 @@
+import { derived } from 'svelte/store';
+import {
+  areConnectionMapsEqual,
+  errorMessages,
+  type NodeConnection,
+  type HandleType
+} from '@xyflow/system';
+
+import { useStore } from '$lib/store';
+import { getContext } from 'svelte';
+
+const error014 = errorMessages['error014']();
+
+type UseNodeConnectionsParams = {
+  type?: HandleType;
+  handleId?: string;
+  nodeId?: string;
+  // TODO: Svelte 5
+  //   onConnect?: (connections: Connection[]) => void;
+  //   onDisconnect?: (connections: Connection[]) => void;
+};
+
+const initialConnections: NodeConnection[] = [];
+
+/**
+ * Hook to retrieve all edges connected to a node. Can be filtered by handle type and id.
+ *
+ * @public
+ * @param param.nodeId - node id - optional if called inside a custom node
+ * @param param.type - filter by handle type 'source' or 'target'
+ * @param param.handleId - filter by handle id (this is only needed if the node has multiple handles of the same type)
+ * @todo @param param.onConnect - gets called when a connection is established
+ * @todo @param param.onDisconnect - gets called when a connection is removed
+ * @returns an array with connections
+ */
+export function useNodeConnections({ type, nodeId, handleId }: UseNodeConnectionsParams = {}) {
+  const { edges, connectionLookup } = useStore();
+
+  const _nodeId = getContext<string>('svelteflow__node_id');
+  const currentNodeId = nodeId ?? _nodeId;
+
+  if (!currentNodeId) {
+    throw new Error(error014);
+  }
+
+  let prevConnections: Map<string, NodeConnection> | undefined = undefined;
+
+  return derived(
+    [edges, connectionLookup],
+    ([, connectionLookup], set) => {
+      const nextConnections = connectionLookup.get(
+        `${currentNodeId}${type ? (handleId ? `-${type}-${handleId}` : `-${type}`) : ''}`
+      );
+
+      if (!areConnectionMapsEqual(nextConnections, prevConnections)) {
+        prevConnections = nextConnections;
+        set(Array.from(prevConnections?.values() || []));
+      }
+    },
+    initialConnections
+  );
+}

packages/svelte/src/lib/index.ts

@@ -31,6 +31,7 @@ export * from '$lib/hooks/useUpdateNodeInternals';
 export * from '$lib/hooks/useConnection';
 export * from '$lib/hooks/useNodesEdges';
 export * from '$lib/hooks/useHandleConnections';
+export * from '$lib/hooks/useNodeConnections';
 export * from '$lib/hooks/useNodesData';
 export * from '$lib/hooks/useInternalNode';
 export { useInitialized, useNodesInitialized } from '$lib/hooks/useInitialized';

packages/system/src/constants.ts

@@ -24,6 +24,8 @@ export const errorMessages = {
     `Node with id "${id}" does not exist, it may have been removed. This can happen when a node is deleted before the "onNodeClick" handler is called.`,
   error013: (lib: string = 'react') =>
     `It seems that you haven't loaded the styles. Please import '@xyflow/${lib}/dist/style.css' or base.css to make sure everything is working properly.`,
+  error014: () =>
+    'useNodeConnections: No node ID found. Call useNodeConnections inside a custom Node or provide a node ID.',
 };
 
 export const infiniteExtent: CoordinateExtent = [

packages/system/src/types/general.ts

@@ -33,10 +33,15 @@ export type Connection = {
   targetHandle: string | null;
 };
 
+// TODO: remove in next version
 export type HandleConnection = Connection & {
   edgeId: string;
 };
 
+export type NodeConnection = Connection & {
+  edgeId: string;
+};
+
 export enum ConnectionMode {
   Strict = 'strict',
   Loose = 'loose',

packages/system/src/utils/store.ts

@@ -1,4 +1,4 @@
-import { infiniteExtent } from '..';
+import { HandleConnection, infiniteExtent } from '..';
 import {
   NodeBase,
   CoordinateExtent,
@@ -42,7 +42,7 @@ const adoptUserNodesDefaultOptions = {
   checkEquality: true,
 };
 
-function mergeObjects<T extends Record<string, any>>(base: T, incoming?: Partial<T>): T {
+function mergeObjects<T extends Record<string, unknown>>(base: T, incoming?: Partial<T>): T {
   const result = { ...base };
   for (const key in incoming) {
     if (incoming[key] !== undefined) {
@@ -439,22 +439,56 @@ export async function panBy({
   return Promise.resolve(transformChanged);
 }
 
+/**
+ * this function adds the connection to the connectionLookup
+ * at the following keys: nodeId-type-handleId, nodeId-type and nodeId
+ * @param type type of the connection
+ * @param connection connection that should be added to the lookup
+ * @param connectionKey at which key the connection should be added
+ * @param connectionLookup reference to the connection lookup
+ * @param nodeId nodeId of the connection
+ * @param handleId handleId of the conneciton
+ */
+function addConnectionToLookup(
+  type: 'source' | 'target',
+  connection: HandleConnection,
+  connectionKey: string,
+  connectionLookup: ConnectionLookup,
+  nodeId: string,
+  handleId: string | null
+) {
+  // We add the connection to the connectionLookup at the following keys
+  // 1. nodeId, 2. nodeId-type, 3. nodeId-type-handleId
+  // If the key already exists, we add the connection to the existing map
+  let key = nodeId;
+  const nodeMap = connectionLookup.get(key) || new Map();
+  connectionLookup.set(key, nodeMap.set(connectionKey, connection));
+
+  key = `${nodeId}-${type}`;
+  const typeMap = connectionLookup.get(key) || new Map();
+  connectionLookup.set(key, typeMap.set(connectionKey, connection));
+
+  if (handleId) {
+    key = `${nodeId}-${type}-${handleId}`;
+    const handleMap = connectionLookup.get(key) || new Map();
+    connectionLookup.set(key, handleMap.set(connectionKey, connection));
+  }
+}
+
 export function updateConnectionLookup(connectionLookup: ConnectionLookup, edgeLookup: EdgeLookup, edges: EdgeBase[]) {
   connectionLookup.clear();
   edgeLookup.clear();
 
   for (const edge of edges) {
-    const { source, target, sourceHandle = null, targetHandle = null } = edge;
+    const { source: sourceNode, target: targetNode, sourceHandle = null, targetHandle = null } = edge;
 
-    const sourceKey = `${source}-source-${sourceHandle}`;
-    const targetKey = `${target}-target-${targetHandle}`;
+    const connection = { edgeId: edge.id, source: sourceNode, target: targetNode, sourceHandle, targetHandle };
+    const sourceKey = `${sourceNode}-${sourceHandle}`;
+    const targetKey = `${targetNode}-${targetHandle}`;
 
-    const prevSource = connectionLookup.get(sourceKey) || new Map();
-    const prevTarget = connectionLookup.get(targetKey) || new Map();
-    const connection = { edgeId: edge.id, source, target, sourceHandle, targetHandle };
+    addConnectionToLookup('source', connection, targetKey, connectionLookup, sourceNode, sourceHandle);
+    addConnectionToLookup('target', connection, sourceKey, connectionLookup, targetNode, targetHandle);
 
     edgeLookup.set(edge.id, edge);
-    connectionLookup.set(sourceKey, prevSource.set(`${target}-${targetHandle}`, connection));
-    connectionLookup.set(targetKey, prevTarget.set(`${source}-${sourceHandle}`, connection));
   }
 }