Edges

Edges are what connects your nodes into a map.

They cannot exist on their own and need nodes to which they are connected.

Each edge requires a unique id, a source node and a target node id. Anything else is optional.

You can check the full options for an edge element in the TypeDocs here.

Usage

Generally you create edges by adding them to the model-value or the edges prop of the Vue Flow component.

<script>
import { VueFlow } from '@vue-flow/core'

export default defineComponent({
  components: { VueFlow },
  data() {
    return {
      elements: [
        {
          id: '1',
          position: { x: 50, y: 50 },
          label: 'Node 1',
        },
        {
          id: '2',
          position: { x: 50, y: 250 },
          label: 'Node 2',
        }
      ]
    }
  },
  mounted() {
    // Add an edge after mount
    this.elements.push(
      {
        id: 'e1-2',
        source: '1',
        target: '2',
      }
    )
  }
})
</script>
<template>
  <div style="height: 300px">
    <VueFlow v-model="elements" />
  </div>
</template>

For more advanced graphs that require more state access you will want to use the useVueFlow composable. useVueFlow will provide you with an addEdges utility function, which you can use to add edges directly to the state.

<script setup>
import { VueFlow, useVueFlow } from '@vue-flow/core'

const initialNodes = ref([
  {
    id: '1',
    position: { x: 50, y: 50 },
    label: 'Node 1',
  },
  {
    id: '2',
    position: { x: 50, y: 250 },
    label: 'Node 2',
  }
])
const { addEdges } = useVueFlow({
  nodes: initialNodes,
})

onMounted(() => {
  // Add an edge after mount
  addEdges([
     {
        source: '1',
        target: '2',
        sourceHandle: null,
        targetHandle: null,
     }
  ])
})
</script>
<template>
  <div style="height: 300px">
    <VueFlow />
  </div>
</template>

You can also apply changes (like removing elements safely) using the applyEdgeChanges utility function, which expects an array of changes to be applied to the currently stored edges.

Default Edge-Types

Vue Flow comes with built-in edges that you can use right out of the box. These edge types include default (bezier), step, smoothstep and straight.

Default Edge (Bezier)

A bezier edge has a curved path.

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

Step Edge

A step edge has a straight path with a step towards the target.

const edges = [
  {
    id: 'e1-2',
    type: 'step',
    source: '1',
    target: '2',
  }
]

Smoothstep Edge

The same as the step edge though with a border radius on the step (rounded step).

const edges = [
  {
    id: 'e1-2',
    type: 'smoothstep',
    source: '1',
    target: '2',
  }
]

Straight Edge

A simple straight path.

const edges = [
  {
    id: 'e1-2',
    type: 'straight',
    source: '1',
    target: '2',
  }
]

Custom Edges

In addition to the default edge types from the previous chapter, you can define any amount of custom edge-types. Edge-types are inferred from your edge's definition.

const edges = [
  {
    id: 'e1-2',
    type: 'special',
    source: '1',
    target: '2',
  },
]

Vue Flow will now try to resolve this edge-type to a component. First and foremost we will look for a definition in the edgeTypes object of the state. After that we will try to resolve the component to a globally registered one that matches the exact name. Finally, we will check if a template slot has been provided to fill the edge-type.

If none of these methods succeed in resolving the component the default (bezier) edge-type will be used as a fallback.

Template slots

The easiest way to define custom edges is, by passing them as template slots. Your custom edge-types are dynamically resolved to slot-names, meaning an edge with the type custom will expect a slot to have the name edge-custom.

<script setup>
import { VueFlow } from '@vue-flow/core'
import CustomEdge from './CustomEdge.vue'

const elements = ref([
  {
    id: '1',
    label: 'Node 1',
    position: { x: 50, y: 50 },
  },
  {
    id: '2',
    label: 'Node 2',
    position: { x: 50, y: 250 },
  },
  {
    id: 'e1-2',
    type: 'custom',
    source: '1',
    target: '2',
  },
])
</script>
<template>
  <VueFlow v-model="elements">
    <template #edge-custom="props">
      <CustomEdge v-bind="props" />
    </template>
  </VueFlow>
</template>

Edge-types object

You can also define edge-types by passing an object as a prop to the VueFlow component (or as an option to the composable).

WARNING

When doing this, mark your components as raw (using the designated function from the vue library) to avoid them being turned into reactive objects. Otherwise, vue will throw a warning in the console.

<script setup>
import { markRaw } from 'vue'
import CustomEdge from './CustomEdge.vue'

const edgeTypes = {
  custom: markRaw(CustomEdge),
}

const elements = ref([
  {
    id: '1',
    label: 'Node 1',
  },
  {
    id: '1',
    label: 'Node 1',
  },
    {
    id: 'e1-2',
    type: 'custom',
    source: '1',
    target: '2',
  },
])
</script>
<template>
  <div style="height: 300px">
    <VueFlow v-model="elements" :edge-types="edgeTypes" />
  </div>
</template>

Edge Template

You can also set a template per edge, which will overwrite the edge-type component but will retain the type otherwise.

<script setup>
import { markRaw } from 'vue'
import CustomEdge from './CustomEdge.vue'

const elements = ref([
  {
    id: '1',
    label: 'Node 1',
    position: { x: 0, y: 0 },
  },
  {
    id: '2',
    label: 'Node 2',
    position: { x: 0, y: 150 },
  },
    {
    id: '3',
    label: 'Node 3',
    position: { x: 0, y: 300 },
  },
  {
    id: 'e1-2',
    source: '1',
    target: '2',
  },
  {
    id: 'e1-3',
    source: '1',
    target: '2',
    template: markRaw(CustomEdge),
  },
])
</script>
<template>
  <div style="height: 300px">
    <VueFlow v-model="elements" />
  </div>
</template>

Custom Edge Props

Your custom edges are wrapped so that the basic functions like selecting work. But you might want to extend on that functionality or implement your own business logic inside of edges, therefore your edges receive the following props:

Name	Definition	Type	Optional
id	Edge id	string	false
source	The source node id	string	false
target	The target node id	string	false
sourceNode	The source node	GraphNode	false
targetNode	The target node	GraphNode	false
sourceX	X position of source handle	number	false
sourceY	Y position of source handle	number	false
targetX	X position of target handle	number	false
targetY	Y position of target handle	number	false
type	Edge type	string	true
sourceHandleId	Source handle id	string	true
targetHandleId	Target handle id	string	true
data	Custom data object	Any object	true
events	Edge events and custom events	EdgeEventsOn	true
label	Edge label	string, Component	true
labelStyle	Additional label styles	CSSProperties	true
labelShowBg	Enable/Disable label bg	boolean	true
labelBgPadding	Edge label bg padding	number	true
labelBgBorderRadius	Edge label bg border radius	number	true
selected	Is edge selected	boolean	true
animated	Is edge animated	boolean	true
updatable	Is edge updatable	EdgeUpdatable	true
markerEnd	Edge marker id	string	true
markerStart	Edge marker id	string	true
curvature	Edge path curvature	number	true

(Custom) Edge Events

In addition to the event handlers that you can access through useVueFlow or the Vue Flow component, you can also pass in event handlers in your initial edge definition, or you can access the edge events through the events prop passed to your edge components.

<script setup>
import { VueFlow } from '@vue-flow/core'

const elements = ref([
  {
    id: '1',
    label: 'Node 1',
    position: { x: 50, y: 50 },
  },
  {
    id: '2',
    label: 'Node 2',
    position: { x: 50, y: 150 },
  },
  {
    id: 'edge1-2',
    source: '1',
    target: '2',
    events: {
      click: () => {
        console.log('Edge clicked')
      },
      change: () => {
        console.log('Something changed')
      },
    },
  }
])
</script>

As you can see above, you can also pass in custom event handlers. These will not be called by Vue Flow but can be used to forward callback functions to your custom components. The click handler is part of the EdgeEventsHandler type, meaning it will be triggered when the edge is clicked.

<script lang="ts" setup>
import type { EdgeProps, EdgeEventsOn } from '@vue-flow/core'

// define your events
interface CustomEdgeEvents {
  click: EdgeEventsOn['click']
  customEvent: (input: string) => void
}

interface CustomEdgeProps extends EdgeProps<any, CustomEdgeEvents> {
  id: string
  events: CustomEdgeEvents
}

props.events.click(() => {
  console.log(`Edge ${props.id} clicked`)
})

// custom events are just functions, they are not hooks which you can listen to like `click`
props.events.customEvent('custom event triggered')
</script>
<template>
  <!-- Omitted for simplicty -->
</template>

Edges #

Usage #

Default Edge-Types #

Default Edge (Bezier) #

Step Edge #

Smoothstep Edge #

Straight Edge #

Custom Edges #

Template slots #

Edge-types object #

Edge Template #

Custom Edge Props #

(Custom) Edge Events #