React Flow 边事件处理实战：鼠标事件、键盘操作及连接规则设置（附完整代码）

本文为《React Agent：从零开始构建 AI 智能体》专栏系列文章。 专栏地址：https://blog.csdn.net/suiyingy/category_12933485.html。项目地址：https://gitee.com/fgai/react-agent（含完整代码示​例与实战源）。完整介绍：https://blog.csdn.net/suiyingy/article/details/146983582。

        边可以响应多种用户操作，如点击、双击、鼠标悬停等。通过绑定相应的事件处理函数，实现边的交互功能。点击边弹出其详细信息窗口；鼠标悬停时显示工具提示，说明边所代表的关系含义。

1 鼠标悬停

        下面程序为鼠标悬停事件示例，显示边的信息、改变线条颜色、宽度和线型。

import React, { useCallback, useState } from 'react';
import {ReactFlow,useNodesState,useEdgesState,addEdge,
} from 'reactflow';
import 'reactflow/dist/style.css';const initialNodes = [{ id: '1', position: { x: 0, y: 0 }, data: { label: '1' } },{ id: '2', position: { x: 0, y: 100 }, data: { label: '2' } },
];const initialEdges = [{ id: 'e1-2', source: '1', target: '2',type: 'default' }
];export default function FlowComponent() {const [nodes, setNodes, onNodesChange] = useNodesState(initialNodes);const [edges, setEdges, onEdgesChange] = useEdgesState(initialEdges);const [hoveredEdgeId, setHoveredEdgeId] = useState(null);const onConnect = useCallback((params) => setEdges((eds) => addEdge(params, eds)),[setEdges]);// 动态获取边样式const getEdgeStyle = (edge) => {return hoveredEdgeId === edge.id ? {stroke: 'red',strokeWidth: 3,strokeDasharray: '5 5',}: {};};return (<div style={{ height: '500px', width: '100%' }}><ReactFlownodes={nodes}edges={edges.map(edge => ({...edge,style: getEdgeStyle(edge)}))}onNodesChange={onNodesChange}onEdgesChange={onEdgesChange}onConnect={onConnect}onEdgeMouseEnter={(event, edge) => setHoveredEdgeId(edge.id)}onEdgeMouseLeave={() => setHoveredEdgeId(null)}fitView/></div>);
}

        运行程序后结果如下图所示。

图1 边 - 鼠标悬停

2 鼠标单击

        下面程序为鼠标单击事件示例，显示边的信息。

export default function App() {const [nodes, setNodes, onNodesChange] = useNodesState(initialNodes);const [edges, setEdges, onEdgesChange] = useEdgesState(initialEdges);const onConnect = useCallback((params) => setEdges((eds) => addEdge(params, eds)),[setEdges],);const onEdgeClick = useCallback((event, edge) => {console.log('Clicked edge:', edge);// 这里可以添加更多逻辑，比如显示模态框等}, []);return (<div style={{ height: '500px' }}><ReactFlownodes={nodes}edges={edges}onNodesChange={onNodesChange}onEdgesChange={onEdgesChange}onConnect={onConnect}onEdgeClick={onEdgeClick}fitView/></div>);
}

        运行程序后结果如下图所示。

图2 边 - 鼠标单击

3 鼠标双击

        下面程序为鼠标双击事件示例。

export default function App() {const [nodes, setNodes, onNodesChange] = useNodesState(initialNodes);const [edges, setEdges, onEdgesChange] = useEdgesState(initialEdges);const onConnect = useCallback((params) => setEdges((eds) => addEdge(params, eds)),[setEdges],);const handleEdgeDoubleClick = (event, edge) => {alert(`双击了边：${edge.id}`);// 这里可以添加更多自定义逻辑，比如：// - 删除边// - 编辑边属性// - 高亮关联节点等};return (<div style={{ height: '500px' }}><ReactFlownodes={nodes}edges={edges}onNodesChange={onNodesChange}onEdgesChange={onEdgesChange}onConnect={onConnect}onEdgeDoubleClick={handleEdgeDoubleClick}fitView/></div>);
}

4 键盘事件

        同样地，边也支持键盘事件，示例如下：

export default function App() {const [nodes, setNodes, onNodesChange] = useNodesState(initialNodes);const [edges, setEdges, onEdgesChange] = useEdgesState(initialEdges);// 处理连接线const onConnect = useCallback((params) => setEdges((eds) => addEdge(params, eds)),[setEdges],);// 键盘事件处理const handleKeyDown = useCallback((event) => {if (event.key === 'Delete') {alert('键盘Delete键被按下')}}, [setNodes, setEdges]);return (<div style={{ height: '500px', outline: 'none' }} tabIndex={0} onKeyDown={handleKeyDown}><ReactFlownodes={nodes}edges={edges}onNodesChange={onNodesChange}onEdgesChange={onEdgesChange}onConnect={onConnect}fitView/></div>);
}

5 连接事件

        在 React Flow 中，边的连接和断开是常见操作。当用户尝试连接两个节点时，系统需要验证连接的合法性，如检查节点的输入输出端口是否匹配、是否存在循环连接等。断开连接时需要处理相关的数据更新和视觉效果变化。可以通过onConnect 和 onEdgesDelete 事件进行自定义逻辑处理。

        onConnect示例程序如下所示。

export default function App() {const [nodes, setNodes, onNodesChange] = useNodesState(initialNodes);const [edges, setEdges, onEdgesChange] = useEdgesState(initialEdges);const onConnect = useCallback((params) => {// 查找源节点和目标节点const sourceNode = nodes.find(node => node.id === params.source);const targetNode = nodes.find(node => node.id === params.target);// 打印节点信息console.log('连接起始端点:', sourceNode);console.log('连接终止端点:', targetNode);// 添加连接边setEdges((eds) => addEdge(params, eds));},[setEdges, nodes] // 添加nodes依赖确保获取最新数据);return (<div style={{ height: '500px' }}><ReactFlownodes={nodes}edges={edges}onNodesChange={onNodesChange}onEdgesChange={onEdgesChange}onConnect={onConnect}fitView/></div>);
}

        运行程序后结果如下图所示。

图3 onConnect 连接

6 连接规则

        我们也可以设置连接规则，例如下面程序不允许自身内部进行连接。

import React, { useCallback } from 'react';
import { ReactFlow, Handle, useNodesState, useEdgesState, addEdge } from 'reactflow';
import 'reactflow/dist/style.css';
import { FiDatabase, FiCloud } from 'react-icons/fi';
import { toast, Toaster } from 'react-hot-toast'; // 添加Toast组件// 自定义节点组件 npm install react-hot-toast
const CustomNode = ({ id, data, selected }) => {return (<div className={`custom-node ${selected ? 'selected' : ''}`}><Handletype="target"position="top"className="!bg-teal-500"// isValidConnection={(connection) => //   connection.source !== id  // 禁止自连接// }/><div className="node-header"><FiCloud className="node-icon" /><h3 className="node-title">{data.label}</h3></div><div className="node-body"><FiDatabase className="node-icon" /><span className="node-info">{data.content}</span></div><Handletype="source"position="bottom"className="!bg-purple-500"/><Handletype="source"position="right"id={`${id}-output-2`}className="!bg-pink-500"style={{ top: '30%' }}/></div>);
};const initialNodes = [{ id: '1', position: { x: 0, y: 0 }, data: { label: '开始节点',content: '输入数据源'},type: 'custom',},{ id: '2', position: { x: 200, y: 150 }, data: { label: '处理节点',content: '数据处理流程'},type: 'custom',},
];const initialEdges = [{ id: 'e1-2', source: '1', target: '2',animated: true,style: { stroke: '#94a3b8' },
}];const nodeTypes = {custom: CustomNode,
};// 节点样式
const nodeStyle = `.custom-node {background: linear-gradient(145deg, #ffffff, #f1f5f9);border-radius: 8px;border: 2px solid #cbd5e1;box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);padding: 16px;min-width: 200px;transition: all 0.2s ease;}.custom-node.selected {border-color: #6366f1;box-shadow: 0 4px 15px rgba(99, 102, 241, 0.2);}.custom-node:hover {transform: translateY(-2px);}.node-header {display: flex;align-items: center;margin-bottom: 12px;border-bottom: 1px solid #e2e8f0;padding-bottom: 8px;}.node-title {margin: 0;font-size: 1.1rem;color: #1e293b;margin-left: 8px;}.node-body {display: flex;align-items: center;color: #64748b;}.node-icon {font-size: 1.2rem;margin-right: 8px;color: #6366f1;}.node-info {font-size: 0.9rem;}.react-flow__handle {width: 14px;height: 14px;border-radius: 3px;border: none;}
`;export default function App() {// 使用useNodesState管理节点状态const [nodes, setNodes, onNodesChange] = useNodesState(initialNodes);const [edges, setEdges, onEdgesChange] = useEdgesState(initialEdges);// 连接处理回调const onConnect = useCallback((connection) => {// 根据不同的输出端口设置边样式const edgeStyle = connection.sourceHandle?.endsWith('-output-2') ? { stroke: '#ec4899' } : { stroke: '#94a3b8' };return setEdges((eds) =>addEdge({...connection,animated: true,style: edgeStyle,}, eds));},[setEdges]);// 连接验证逻辑const isValidConnection = useCallback((connection) => {// 禁止自连接if (connection.source === connection.target) {toast.error('不能连接到自身');// alert('不能连接到自身');return false;}// 检查目标节点是否已有连接const targetConnections = edges.filter((edge) => edge.target === connection.target);if (targetConnections.length > 0) {toast.error('目标节点已有连接');console.log(`连接被禁止：节点 ${connection.target} 已有输入连接`);return false;}return true;},[edges]);return (<div style={{ height: '100vh', background: '#f8fafc' }}><style>{nodeStyle}</style><Toaster position="top-right" /> {/* Toast消息容器 */}<ReactFlow nodes={nodes}edges={edges}onNodesChange={onNodesChange}  // 添加状态变更处理器onEdgesChange={onEdgesChange}onConnect={onConnect}nodeTypes={nodeTypes}isValidConnection={isValidConnection}fitViewstyle={{ background: '#f8fafc' }}connectionLineStyle={{ stroke: '#94a3b8', strokeWidth: 2 }}defaultEdgeOptions={{type: 'smoothstep',animated: true,style: { strokeWidth: 2 }}}/></div>);
}

7 断开事件

        onEdgesDelete 示例程序如下所示。

export default function App() {const [nodes, setNodes, onNodesChange] = useNodesState(initialNodes);const [edges, setEdges, onEdgesChange] = useEdgesState(initialEdges);// 连接处理const onConnect = useCallback((params) => {const sourceNode = nodes.find(n => n.id === params.source);const targetNode = nodes.find(n => n.id === params.target);console.log('[连接建立] 起始节点:', sourceNode);console.log('[连接建立] 终止节点:', targetNode);setEdges((eds) => addEdge(params, eds));},[setEdges, nodes]);// 断开连接处理const onEdgesDeleted = useCallback((deletedEdges) => {deletedEdges.forEach(edge => {const sourceNode = nodes.find(n => n.id === edge.source);const targetNode = nodes.find(n => n.id === edge.target);console.log('[连接断开] 起始节点:', sourceNode);console.log('[连接断开] 终止节点:', targetNode);});},[nodes]);return (<div style={{ height: '500px' }}><ReactFlownodes={nodes}edges={edges}onNodesChange={onNodesChange}onEdgesChange={onEdgesChange}onConnect={onConnect}onEdgesDelete={onEdgesDeleted}  // 添加断开连接处理器fitView/></div>);
}

        运行程序后结果如下图所示。

图4 onEdgesDelete 连接断开

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