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<Handle />

We export a Handle component as a helper for your custom nodes:

import { Handle } from 'react-flow-renderer';

const targetHandleWithValidation = (
<Handle
type="target"
position="left"
isValidConnection={(connection) => connection.source === 'some-id'}
onConnect={(params) => console.log('handle onConnect', params)}
style={{ background: '#fff' }}
/>
);

Prop Types

NameTypeDefaultDescription
type'source' or 'target''source'Defines the handle type
idstringundefinedYou only need this when you have multiple source or target handles (otherwise the node id is used)
position'left', 'right', 'top' or 'bottom''top' for type target, 'bottom' for type sourceHandle position
onConnectfunctionundefinedGets triggered on connect. This callback only gets executed on source handles.
isValidConnectionfunctionundefinedReceives a connection { target: 'some-id', source: 'another-id', sourceHandle: 'source handle id or null', targetHandle: 'target handle id or null' } as param, returns a boolean
isConnectablebooleantrueboolean (this prop gets passed to your custom node component)
styleCSSPropertiesundefinedControls style attributes
classNamestringundefinedAdditional class name

Typescript: The interface of the Handle Prop Types are exported as HandleComponentProps.

Validation

The handle receives the additional class names connecting when the connection line is above the handle and valid if the connection is valid. You can find an example which uses these classes here.

Multiple Handles

If you need multiple source or target handles you can achieve this by creating a custom node. Normally you just use the id of a node for the source or target of an edge. If you have multiple source or target handles you need to pass an id to these handles. These ids can be used by an edge with the sourceHandle and targetHandle options, so that you can connect a specific handle. If you have a node with an id = 1 and a handle with an id = a you can connect this handle by using the node source=1 and the sourceHandle=a.

You can find an example of how to implement a custom node with multiple handles in the custom node guide or in the custom node example.