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<Handle />

To learn what a Handle is, click here.

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

import { Handle } from 'reactflow';

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

type

Description:
Defines the handle type
Type:
'source' or 'target'
Default:
'source'

id

Description:
You only need this when you have multiple source or target handles (otherwise the node id is used)
Type:
string
Default:
undefined

position

Description:
Handle position
Type:
'left', 'right', 'top' or 'bottom'
Default:
'top' for type target, 'bottom' for type source

onConnect

Description:
Gets triggered on connect. This callback only gets executed on source handles.
Type:
function
Default:
undefined

isValidConnection

Description:
Receives 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
Type:
function
Default:
undefined

isConnectable

Description:
boolean (this prop gets passed to your custom node component)
Type:
boolean
Default:
true

style

Description:
Controls style attributes
Type:
CSSProperties
Default:
undefined

className

Description:
Additional class name
Type:
string
Default:
undefined

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.

Dynamic Handles

If you are programmatically changing the position or number of handles in your custom node, you need to update the node internals with the useUpdateNodeInternals hook.

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.

Custom Handle Styles

Since the handle is a div, you can use CSS to style it or pass a style prop to customize a Handle. You can see this in the Add Node On Edge Drop and Simple Floating Edges examples.