React Flow Implementation

React Flow Implementation

Quick Start

import { useCallback } from 'react';
import { ReactFlow, useNodesState, useEdgesState, addEdge } from '@xyflow/react';
import '@xyflow/react/dist/style.css';

const initialNodes = [
  { id: '1', position: { x: 0, y: 0 }, data: { label: 'Node 1' } },
  { id: '2', position: { x: 200, y: 100 }, data: { label: 'Node 2' } },
];

const initialEdges = [{ id: 'e1-2', source: '1', target: '2' }];

export default function Flow() {
  const [nodes, setNodes, onNodesChange] = useNodesState(initialNodes);
  const [edges, setEdges, onEdgesChange] = useEdgesState(initialEdges);

  const onConnect = useCallback(
    (connection) => setEdges((eds) => addEdge(connection, eds)),
    [setEdges]
  );

  return (
    
      
    
  );
}

Implementation gates

Run these in order; do not skip ahead on “looks fine.”

1. Styles on the page — Pass if the bundle that renders `` imports @xyflow/react/dist/style.css (or equivalent CSS pipeline) so nodes/edges are visible and hit-targets match visuals.
2. useReactFlow boundary — Pass if every caller of useReactFlow() is a descendant of that wraps the same tree as (or you have intentionally split stores and can name both roots).
3. Stable nodeTypes / edgeTypes — Pass if those maps are module-scope constants or useMemo with stable deps—not a new { ... } literal each render in the component that renders ``.
4. Handles match edges — Pass if for nodes with multiple Handle ids, every edge that must land on a specific handle sets sourceHandle / targetHandle accordingly (or you accept default handle resolution deliberately).

See ADDITIONAL_COMPONENTS.md for MiniMap, Controls, Background, NodeToolbar, and NodeResizer patterns.

Core Patterns

TypeScript Types

import type { Node, Edge, NodeProps, BuiltInNode } from '@xyflow/react';

// Define custom node type with data shape
type CustomNode = Node<{ value: number; label: string }, 'custom'>;

// Combine with built-in nodes
type MyNode = CustomNode | BuiltInNode;
type MyEdge = Edge<{ weight?: number }>;

// Use throughout app
const [nodes, setNodes] = useNodesState(initialNodes);

Custom Nodes

import { memo } from 'react';
import { Handle, Position, type NodeProps } from '@xyflow/react';

// Define node type
type CounterNode = Node<{ count: number }, 'counter'>;

// Always wrap in memo for performance
const CounterNode = memo(function CounterNode({ data, isConnectable }: NodeProps) {
  return (
    <>
      
      
        Count: {data.count}
        {/* nodrag prevents dragging when interacting with button */}
         console.log('clicked')}>
          Increment
        
      
      
    </>
  );
});

// Register in nodeTypes (define OUTSIDE component to avoid re-renders)
const nodeTypes = { counter: CounterNode };

// Use in ReactFlow

Multiple Handles

// Use handle IDs when a node has multiple handles of same type


// Connect with specific handles
const edge = {
  id: 'e1-2',
  source: '1',
  sourceHandle: 'a',
  target: '2',
  targetHandle: null
};

Custom Edges

import { BaseEdge, EdgeProps, getSmoothStepPath } from '@xyflow/react';

function CustomEdge({ id, sourceX, sourceY, targetX, targetY, sourcePosition, targetPosition, data }: EdgeProps) {
  const [edgePath, labelX, labelY] = getSmoothStepPath({
    sourceX, sourceY, sourcePosition,
    targetX, targetY, targetPosition,
  });

  return (
    <>
      
      {data?.label}
    </>
  );
}

const edgeTypes = { custom: CustomEdge };

State Management

Controlled (Recommended for Production)

// External state with change handlers
const [nodes, setNodes] = useState(initialNodes);
const [edges, setEdges] = useState(initialEdges);

const onNodesChange = useCallback(
  (changes) => setNodes((nds) => applyNodeChanges(changes, nds)),
  []
);

const onEdgesChange = useCallback(
  (changes) => setEdges((eds) => applyEdgeChanges(changes, eds)),
  []
);

Using useReactFlow

import { useReactFlow, ReactFlowProvider } from '@xyflow/react';

function FlowControls() {
  const {
    getNodes, setNodes, addNodes, updateNodeData,
    getEdges, setEdges, addEdges,
    fitView, zoomIn, zoomOut, setViewport,
    deleteElements, toObject,
  } = useReactFlow();

  const addNode = () => {
    addNodes({ id: `${Date.now()}`, position: { x: 100, y: 100 }, data: { label: 'New' } });
  };

  return Add Node;
}

// Must wrap in provider when using useReactFlow
function App() {
  return (
    
      
      
    
  );
}

Updating Node Data

const { updateNodeData } = useReactFlow();

// Merge with existing data
updateNodeData(nodeId, { label: 'Updated' });

// Replace data entirely
updateNodeData(nodeId, { newField: 'value' }, { replace: true });

Viewport & Fit View

// Fit on initial render


// Programmatic control
const { fitView, setViewport, getViewport, zoomTo } = useReactFlow();

// Fit to specific nodes
fitView({ nodes: [{ id: '1' }, { id: '2' }], duration: 500 });

// Set exact viewport
setViewport({ x: 100, y: 100, zoom: 1.5 }, { duration: 300 });

Connection Validation

const isValidConnection = useCallback((connection: Connection) => {
  // Prevent self-connections
  if (connection.source === connection.target) return false;

  // Custom validation logic
  const sourceNode = getNode(connection.source);
  const targetNode = getNode(connection.target);

  return sourceNode?.type !== targetNode?.type;
}, []);

Common Props Reference

CSS Classes for Interaction

Additional Components

See ADDITIONAL_COMPONENTS.md for MiniMap, Controls, Background, NodeToolbar, NodeResizer.