n-cascader

name	n-cascader
description	A cascader component for displaying and selecting tree-structured data with support for single/multiple selection, async loading, filtering, and various check strategies
author	jiaiyan
version	1.0.0

n-cascader Component

The n-cascader component is used to display and select tree-structured data. It supports single and multiple selection modes, async data loading, filtering, and various check strategies for flexible selection behavior.

When to Use

Use n-cascader when you need to:

• Select from hierarchical data (e.g., region selection, category selection)
• Build multi-level navigation or selection interfaces
• Support both single and multiple selection in tree structures
• Load data asynchronously as users navigate
• Filter through large hierarchical datasets
• Display selected values as paths or individual items

Basic Usage

Single Selection

<template>
  <n-cascader
    v-model:value="value"
    placeholder="Select option"
    :options="options"
    check-strategy="child"
    @update:value="handleUpdateValue"
  />
</template>

<script setup>
import { ref } from 'vue'

const value = ref(null)

const options = [
  {
    label: 'Asia',
    value: 'asia',
    children: [
      {
        label: 'China',
        value: 'china',
        children: [
          { label: 'Beijing', value: 'beijing' },
          { label: 'Shanghai', value: 'shanghai' }
        ]
      }
    ]
  }
]

const handleUpdateValue = (value) => {
  console.log(value)
}
</script>

Multiple Selection

<template>
  <n-cascader
    v-model:value="value"
    multiple
    placeholder="Select options"
    clearable
    :options="options"
    cascade
    check-strategy="all"
    @update:value="handleUpdateValue"
  />
</template>

<script setup>
import { ref } from 'vue'

const value = ref([])
const options = []
</script>

Different Sizes

<template>
  <n-space vertical>
    <n-cascader
      v-model:value="value"
      placeholder="Small"
      :options="options"
      size="small"
    />
    <n-cascader
      v-model:value="value"
      placeholder="Medium (default)"
      :options="options"
      size="medium"
    />
    <n-cascader
      v-model:value="value"
      placeholder="Large"
      :options="options"
      size="large"
    />
  </n-space>
</template>

API Reference

Props

Name	Type	Default	Description
value / v-model:value	string | number | Array<number | string> | null	undefined	Value of the cascader.
allow-checking-not-loaded	boolean	false	Whether to allow cascade checking on not loaded nodes.
cascade	boolean	true	Whether to cascade the checkbox selection onto children.
check-strategy	'all' | 'parent' | 'child'	'all'	The way to show checked options.
children-field	string	'children'	The children field in CascaderOption.
clearable	boolean	false	Whether the cascader is clearable.
clear-filter-after-select	boolean	true	Whether to clear filter keyword after select.
default-value	string | number | Array<number | string> | null	null	Default selected value.
disabled	boolean	false	Whether to disable the cascader.
disabled-field	string	'disabled'	The disabled field in CascaderOption.
ellipsis-tag-popover-props	PopoverProps	undefined	Popover props of the preview ellipsis tag.

CascaderOption Properties

Name	Type	Description
label	string	Label of the option.
value	string | number	Value of the option.
disabled?	boolean	Whether this option is disabled.
children?	CascaderOption[]	The children options.

Events

Name	Parameters	Description
update:value	(value, option, pathValues)	Triggered when value changes.
update:show	(value: boolean)	Triggered when menu opens/closes.
blur	()	Triggered on blur.
focus	()	Triggered on focus.
load	(option: CascaderOption) => Promise<void>	Callback when a node is loaded (for remote).

Slots

Name	Parameters	Description
action	()	Action content in the cascading menu.
arrow	()	Arrow content in the cascading menu.
empty	()	Empty state slot for options.
not-found	()	Data not found slot when searching.

Methods

Name	Type	Description
blur	() => void	Blur the cascader.
focus	() => void	Focus the cascader.
getCheckedData	() => { keys, options }	Get checked data.
getIndeterminateData	() => { keys, options }	Get indeterminate data.

Common Patterns

Async Loading

<template>
  <n-cascader
    v-model:value="value"
    placeholder="Select option"
    :options="options"
    remote
    :on-load="handleLoad"
  />
</template>

<script setup>
import { ref } from 'vue'

const value = ref(null)
const options = ref([
  {
    label: 'Root',
    value: 'root'
  }
])

const handleLoad = async (option) => {
  const children = await fetchChildren(option.value)
  option.children = children
}
</script>

Check Strategies

<template>
  <n-space vertical>
    <n-radio-group v-model:value="checkStrategy">
      <n-radio-button value="all">All</n-radio-button>
      <n-radio-button value="parent">Parent</n-radio-button>
      <n-radio-button value="child">Child</n-radio-button>
    </n-radio-group>

    <n-cascader
      multiple
      cascade
      :check-strategy="checkStrategy"
      :options="options"
    />
  </n-space>
</template>

<script setup>
import { ref } from 'vue'

const checkStrategy = ref('all')
</script>

Custom Field Names

<template>
  <n-cascader
    :options="options"
    label-field="name"
    value-field="id"
    children-field="items"
  />
</template>

<script setup>
const options = [
  {
    name: 'Category',
    id: 'cat1',
    items: [
      { name: 'Sub Category', id: 'sub1' }
    ]
  }
]
</script>

Filterable with Hover Trigger

<template>
  <n-cascader
    v-model:value="value"
    placeholder="Select option"
    :options="options"
    :expand-trigger="'hover'"
    :filterable="true"
  />
</template>

Custom Label Rendering

<template>
  <n-cascader
    v-model:value="value"
    :options="options"
    :render-label="renderLabel"
  />
</template>

<script setup>
import { h } from 'vue'

const renderLabel = (option) => {
  return h('span', { style: { fontWeight: 'bold' } }, option.label)
}
</script>

Large Data Handling

<template>
  <n-cascader
    v-model:value="value"
    placeholder="Select from large dataset"
    :options="options"
    :virtual-scroll="true"
    :filterable="true"
  />
</template>

Using Methods via Ref

<template>
  <n-space item-style="display: flex; align-item: center;">
    <n-button @click="handleClick">Focus then blur in 1 second</n-button>
    <n-cascader ref="cascaderRef" style="width: 200px" />
  </n-space>
</template>

<script setup>
import { ref } from 'vue'

const cascaderRef = ref(null)

const handleClick = () => {
  cascaderRef.value?.focus()
  setTimeout(() => {
    cascaderRef.value?.blur()
  }, 1000)
}
</script>

Best Practices

1. Choose appropriate check-strategy: Use 'child' when you only want leaf nodes selected, 'parent' for cleaner display when all children are selected, and 'all' for full flexibility.

2. Use cascade wisely: Enable cascade when parent-child selection should be linked. Disable it for independent selection behavior.

3. Implement async loading for large datasets: Use remote and on-load for lazy loading to improve initial render performance.

4. Enable virtual-scroll for large data: Keep virtual-scroll: true (default) for smooth scrolling with thousands of options.

5. Customize field names for backend data: Use label-field, value-field, and children-field to match your API response structure without data transformation.

6. Use show-path for clarity: Keep show-path: true to show the full selection path, helping users understand their selection context.

7. Handle disabled nodes carefully: When using allow-checking-not-loaded, be aware of consistency between frontend and backend checking logic.

8. Use max-tag-count: 'responsive': For multiple selection with many items, this keeps the display clean and responsive.