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# UTreeView 树型视图

- [示例](#示例)
    - [基本用法](#基本用法)
    - [选项值](#选项值)
    - [只读、禁用、禁用某一项](#只读-禁用-禁用某一项)
    - [异步加载](#异步加载)
    - [Tag 和 Data 混合](#tag-和-data-混合)
    - [字段路径](#字段路径)
    - [手风琴](#手风琴)
    - [展开/折叠触发方式](#展开折叠触发方式)
    - [可取消](#可取消)
    - [节点显示/隐藏](#节点显示隐藏)
    - [多选](#多选)
    - [其他方法](#其他方法)
- [UTreeView API](#utreeview-api)
    - [Props/Attrs](#propsattrs)
    - [Slots](#slots)
    - [Events](#events)
    - [Methods](#methods)
- [UTreeViewNode API](#utreeviewnode-api)
    - [Props/Attrs](#propsattrs-2)
    - [Slots](#slots-2)
    - [Events](#events-2)

## 示例
### 基本用法

有两种书写方式，这里推荐使用Data方式，因为树型结构的数据有时非常多。

#### Tag 方式

``` html { width: 30% }
<u-tree-view>
    <u-tree-view-node text="节点 1">
        <u-tree-view-node text="节点 1.1"></u-tree-view-node>
        <u-tree-view-node text="节点 1.2">
            <u-tree-view-node text="节点 1.2.1"></u-tree-view-node>
            <u-tree-view-node text="节点 1.2.2"></u-tree-view-node>
        </u-tree-view-node>
        <u-tree-view-node text="节点 1.3"></u-tree-view-node>
        <u-tree-view-node text="节点 1.4"></u-tree-view-node>
    </u-tree-view-node>
    <u-tree-view-node text="节点 2"></u-tree-view-node>
    <u-tree-view-node text="节点 3">
        <u-tree-view-node text="节点 3.1"></u-tree-view-node>
        <u-tree-view-node text="节点 3.2"></u-tree-view-node>
    </u-tree-view-node>
</u-tree-view>
```

#### Data 方式

``` html { width: 30% }
<u-tree-view :data="[
    { text: '节点 1', children: [
        { text: '节点 1.1' },
        { text: '节点 1.2', children: [
            { text: '节点 1.2.1' },
            { text: '节点 1.2.2' },
        ] },
        { text: '节点 1.3' },
        { text: '节点 1.4' },
    ] },
    { text: '节点 2' },
    { text: '节点 3', children: [
        { text: '节点 3.1' },
        { text: '节点 3.2' },
    ] },
]"></u-tree-view>
```

#### 自定义模板

Tag 方式很容易自定义模板，而 Data 方式却不好扩展。我们提供了一个名为`text`的作用域插槽，可以很轻松地处理这个问题。

``` html { width: 30% }
<u-tree-view :data="[
    { text: '文件夹1', type: 'directory', children: [
        { text: '文件夹1.1', type: 'directory' },
        { text: '文件夹1.2', type: 'directory', children: [
            { text: '文件1.2.1', type: 'file' },
            { text: '文件1.2.2', type: 'file' },
        ] },
        { text: '文件1.3', type: 'file' },
        { text: '文件1.4', type: 'file' },
    ] },
    { text: '文件夹2', type: 'directory' },
    { text: '文件夹3', type: 'directory', children: [
        { text: '文件3.1', type: 'file' },
        { text: '文件3.2', type: 'file' },
    ] },
]">
    <span slot="text" slot-scope="{ node, expanded, text }">
        {{ node.type === 'directory' ? (expanded ? '📂' : '📁') : '📄' }}
        {{ text }}
    </span>
</u-tree-view>
```

但`text`作用域插槽只支持扩展 text 文本内容，如果你的需求更加复杂，建议直接通过继承 UTreeView 相关组件来实现。

### 选项值

#### Tag 方式

``` html { width: 30% }
<u-tree-view value="1.2">
    <u-tree-view-node text="节点 1" value="1">
        <u-tree-view-node text="节点 1.1" value="1.1"></u-tree-view-node>
        <u-tree-view-node text="节点 1.2" value="1.2">
            <u-tree-view-node text="节点 1.2.1" value="1.2.1"></u-tree-view-node>
            <u-tree-view-node text="节点 1.2.2" value="1.2.2"></u-tree-view-node>
        </u-tree-view-node>
        <u-tree-view-node text="节点 1.3" value="1.3"></u-tree-view-node>
        <u-tree-view-node text="节点 1.4" value="1.4"></u-tree-view-node>
    </u-tree-view-node>
    <u-tree-view-node text="节点 2" value="2"></u-tree-view-node>
    <u-tree-view-node text="节点 3" value="3">
        <u-tree-view-node text="节点 3.1" value="3.1"></u-tree-view-node>
        <u-tree-view-node text="节点 3.2" value="3.2"></u-tree-view-node>
    </u-tree-view-node>
</u-tree-view>
```

#### Data 方式

``` html { width: 30% }
<u-tree-view value="1.2" :data="[
    { text: '节点 1', value: '1', children: [
        { text: '节点 1.1', value: '1.1' },
        { text: '节点 1.2', value: '1.2', children: [
            { text: '节点 1.2.1', value: '1.2.1' },
            { text: '节点 1.2.2', value: '1.2.2' },
        ] },
        { text: '节点 1.3', value: '1.3' },
        { text: '节点 1.4', value: '1.4' },
    ] },
    { text: '节点 2', value: '2' },
    { text: '节点 3', value: '3', children: [
        { text: '节点 3.1', value: '3.1' },
        { text: '节点 3.2', value: '3.2' },
    ] },
]"></u-tree-view>
```

### 只读、禁用、禁用某一项

#### Tag 方式

``` html
<u-grid-layout>
    <u-grid-layout-column :span="4">
        <u-tree-view readonly>
            <u-tree-view-node text="节点 1">
                <u-tree-view-node text="节点 1.1"></u-tree-view-node>
                <u-tree-view-node text="节点 1.2">
                    <u-tree-view-node text="节点 1.2.1"></u-tree-view-node>
                    <u-tree-view-node text="节点 1.2.2"></u-tree-view-node>
                </u-tree-view-node>
                <u-tree-view-node text="节点 1.3"></u-tree-view-node>
                <u-tree-view-node text="节点 1.4"></u-tree-view-node>
            </u-tree-view-node>
            <u-tree-view-node text="节点 2"></u-tree-view-node>
            <u-tree-view-node text="节点 3">
                <u-tree-view-node text="节点 3.1"></u-tree-view-node>
                <u-tree-view-node text="节点 3.2"></u-tree-view-node>
            </u-tree-view-node>
        </u-tree-view>
    </u-grid-layout-column>
    <u-grid-layout-column :span="4">
        <u-tree-view disabled>
            <u-tree-view-node text="节点 1">
                <u-tree-view-node text="节点 1.1"></u-tree-view-node>
                <u-tree-view-node text="节点 1.2">
                    <u-tree-view-node text="节点 1.2.1"></u-tree-view-node>
                    <u-tree-view-node text="节点 1.2.2"></u-tree-view-node>
                </u-tree-view-node>
                <u-tree-view-node text="节点 1.3"></u-tree-view-node>
                <u-tree-view-node text="节点 1.4"></u-tree-view-node>
            </u-tree-view-node>
            <u-tree-view-node text="节点 2"></u-tree-view-node>
            <u-tree-view-node text="节点 3">
                <u-tree-view-node text="节点 3.1"></u-tree-view-node>
                <u-tree-view-node text="节点 3.2"></u-tree-view-node>
            </u-tree-view-node>
        </u-tree-view>
    </u-grid-layout-column>
    <u-grid-layout-column :span="4">
        <u-tree-view>
            <u-tree-view-node text="节点 1">
                <u-tree-view-node text="节点 1.1"></u-tree-view-node>
                <u-tree-view-node text="节点 1.2" disabled>
                    <u-tree-view-node text="节点 1.2.1"></u-tree-view-node>
                    <u-tree-view-node text="节点 1.2.2"></u-tree-view-node>
                </u-tree-view-node>
                <u-tree-view-node text="节点 1.3" disabled></u-tree-view-node>
                <u-tree-view-node text="节点 1.4"></u-tree-view-node>
            </u-tree-view-node>
            <u-tree-view-node text="节点 2" disabled></u-tree-view-node>
            <u-tree-view-node text="节点 3">
                <u-tree-view-node text="节点 3.1"></u-tree-view-node>
                <u-tree-view-node text="节点 3.2"></u-tree-view-node>
            </u-tree-view-node>
        </u-tree-view>
    </u-grid-layout-column>
</u-grid-layout>
```

#### Data 方式

``` html { width: 30% }
<u-tree-view :data="[
    { text: '节点 1', children: [
        { text: '节点 1.1' },
        { text: '节点 1.2', disabled: true, children: [
            { text: '节点 1.2.1' },
            { text: '节点 1.2.2'}
        ] },
        { text: '节点 1.3', disabled: true  },
        { text: '节点 1.4' },
    ] },
    { text: '节点 2', disabled: true  },
    { text: '节点 3', children: [
        { text: '节点 3.1' },
        { text: '节点 3.2'}
    ]}
]"></u-tree-view>
```

### 异步加载

``` vue { width: 30% }
<template>
<u-tree-view :data-source="load" text-field="title"></u-tree-view>
</template>
<script>
// 模拟后端请求
const mockRequest = (data, timeout = 300) => new Promise((res, rej) => setTimeout(() => res(data), timeout));

export default {
    methods: {
        load(params) {
            if (!params.node) {
                return mockRequest([
                    { type: 'app', title: '应用1', childrenField: 'services' },
                    { type: 'app', title: '应用2', childrenField: 'services' },
                ]);
            } else if (params.node.type === 'app') {
                return mockRequest([
                    { type: 'service', title: '服务1', childrenField: 'pages' },
                    { type: 'service', title: '服务2', childrenField: 'pages' },
                    { type: 'service', title: '服务3', childrenField: 'pages' },
                ]);
            } else if (params.node.type === 'service') {
                return mockRequest([
                    { type: 'page', title: '页面1', isLeaf: true, childrenField: 'children' },
                    { type: 'page', title: '页面2', isLeaf: true, childrenField: 'children' },
                ]);
            }
        },
    },
}
</script>
```

### Tag 和 Data 混合

``` vue { width: 30% }
<template>
<u-tree-view :data-source="load" text-field="title">
    <u-tree-view-node v-for="app in apps" v-if="app.subType !== 'other'" :text="app.title" :node="app" children-field="services"></u-tree-view-node>
</u-tree-view>
</template>
<script>
// 模拟后端请求
const mockRequest = (data, timeout = 300) => new Promise((res, rej) => setTimeout(() => res(data), timeout));

export default {
    data() {
        return {
            apps: [
                { type: 'app', title: '应用1' },
                { type: 'app', title: '应用2' },
                { type: 'app', title: '应用3', subType: 'other' },
                { type: 'app', title: '应用4' },
            ],
        };
    },
    methods: {
        load(params) {
            if (params.node.type === 'app') {
                return mockRequest([
                    { type: 'service', title: '服务1', childrenField: 'pages' },
                    { type: 'service', title: '服务2', childrenField: 'pages' },
                    { type: 'service', title: '服务3', childrenField: 'pages' },
                ]);
            } else if (params.node.type === 'service') {
                return mockRequest([
                    { type: 'page', title: '页面1' },
                    { type: 'page', title: '页面2' },
                ]);
            } else {
                return mockRequest();
            }
        },
    },
}
</script>
```

### 字段路径

``` vue { width: 30% }
<template>
<u-tree-view :data-source="load" text-field="title"></u-tree-view>
</template>
<script>
// 模拟后端请求
const mockRequest = (data, timeout = 300) => new Promise((res, rej) => setTimeout(() => res(data), timeout));

export default {
    methods: {
        load(params) {
            if (!params.node) {
                return mockRequest([
                    { type: 'app', title: '应用1', childrenField: 'services' },
                    { type: 'app', title: '应用2', childrenField: 'services' },
                ]);
            } else if (params.node.type === 'app') {
                return mockRequest([
                    { type: 'service', title: '服务1', front: {}, childrenField: 'front.pages' },
                    { type: 'service', title: '服务2', front: {}, childrenField: 'front.pages' },
                    { type: 'service', title: '服务3', front: {}, childrenField: 'front.pages' },
                ]);
            } else if (params.node.type === 'service') {
                return mockRequest([
                    { type: 'page', title: '页面1', isLeaf: true, childrenField: 'children' },
                    { type: 'page', title: '页面2', isLeaf: true, childrenField: 'children' },
                ]);
            }
        },
    },
}
</script>
```

### 手风琴

``` html { width: 30% }
<u-tree-view accordion>
    <u-tree-view-node text="节点 1">
        <u-tree-view-node text="节点 1.1">
            <u-tree-view-node text="节点 1.1.1"></u-tree-view-node>
            <u-tree-view-node text="节点 1.1.2"></u-tree-view-node>
        </u-tree-view-node>
        <u-tree-view-node text="节点 1.2">
            <u-tree-view-node text="节点 1.2.1"></u-tree-view-node>
            <u-tree-view-node text="节点 1.2.2"></u-tree-view-node>
        </u-tree-view-node>
        <u-tree-view-node text="节点 1.3">
            <u-tree-view-node text="节点 1.3.1"></u-tree-view-node>
            <u-tree-view-node text="节点 1.3.2"></u-tree-view-node>
        </u-tree-view-node>
        <u-tree-view-node text="节点 1.4"></u-tree-view-node>
    </u-tree-view-node>
    <u-tree-view-node text="节点 2" expanded>
        <u-tree-view-node text="节点 2.1"></u-tree-view-node>
        <u-tree-view-node text="节点 2.2"></u-tree-view-node>
    </u-tree-view-node>
    <u-tree-view-node text="节点 3">
        <u-tree-view-node text="节点 3.1"></u-tree-view-node>
        <u-tree-view-node text="节点 3.2"></u-tree-view-node>
    </u-tree-view-node>
</u-tree-view>
```

### 展开/折叠触发方式

``` html
<u-grid-layout>
    <u-grid-layout-column :span="4" expand-trigger="click">
        <p>整行点击均可触发（默认）</p>
        <u-tree-view>
            <u-tree-view-node text="节点 1" expanded>
                <u-tree-view-node text="节点 1.1" expanded></u-tree-view-node>
                <u-tree-view-node text="节点 1.2" expanded>
                    <u-tree-view-node text="节点 1.2.1"></u-tree-view-node>
                    <u-tree-view-node text="节点 1.2.2"></u-tree-view-node>
                </u-tree-view-node>
                <u-tree-view-node text="节点 1.3"></u-tree-view-node>
                <u-tree-view-node text="节点 1.4"></u-tree-view-node>
            </u-tree-view-node>
            <u-tree-view-node text="节点 2"></u-tree-view-node>
            <u-tree-view-node text="节点 3">
                <u-tree-view-node text="节点 3.1"></u-tree-view-node>
                <u-tree-view-node text="节点 3.2"></u-tree-view-node>
            </u-tree-view-node>
        </u-tree-view>
    </u-grid-layout-column>
    <u-grid-layout-column :span="4">
        <p>仅点击小箭头时触发</p>
        <u-tree-view expand-trigger="click-expander">
            <u-tree-view-node text="节点 1" expanded>
                <u-tree-view-node text="节点 1.1" expanded></u-tree-view-node>
                <u-tree-view-node text="节点 1.2" expanded>
                    <u-tree-view-node text="节点 1.2.1"></u-tree-view-node>
                    <u-tree-view-node text="节点 1.2.2"></u-tree-view-node>
                </u-tree-view-node>
                <u-tree-view-node text="节点 1.3"></u-tree-view-node>
                <u-tree-view-node text="节点 1.4"></u-tree-view-node>
            </u-tree-view-node>
            <u-tree-view-node text="节点 2"></u-tree-view-node>
            <u-tree-view-node text="节点 3">
                <u-tree-view-node text="节点 3.1"></u-tree-view-node>
                <u-tree-view-node text="节点 3.2"></u-tree-view-node>
            </u-tree-view-node>
        </u-tree-view>
    </u-grid-layout-column>
</u-grid-layout>
```

### 可取消

``` html { width: 30% }
<u-tree-view cancelable>
    <u-tree-view-node text="节点 1">
        <u-tree-view-node text="节点 1.1"></u-tree-view-node>
        <u-tree-view-node text="节点 1.2">
            <u-tree-view-node text="节点 1.2.1"></u-tree-view-node>
            <u-tree-view-node text="节点 1.2.2"></u-tree-view-node>
        </u-tree-view-node>
        <u-tree-view-node text="节点 1.3"></u-tree-view-node>
        <u-tree-view-node text="节点 1.4"></u-tree-view-node>
    </u-tree-view-node>
    <u-tree-view-node text="节点 2"></u-tree-view-node>
    <u-tree-view-node text="节点 3">
        <u-tree-view-node text="节点 3.1"></u-tree-view-node>
        <u-tree-view-node text="节点 3.2"></u-tree-view-node>
    </u-tree-view-node>
</u-tree-view>
```

### 节点显示/隐藏

Tag 方式中可以使用`v-show`，Data 方式中可以使用`hidden`属性

``` html { width: 30% }
<u-tree-view cancelable>
    <u-tree-view-node v-show="false" text="节点1">
        <u-tree-view-node text="节点1.1"></u-tree-view-node>
        <u-tree-view-node text="节点1.2">
            <u-tree-view-node text="节点1.2.1"></u-tree-view-node>
            <u-tree-view-node text="节点1.2.2"></u-tree-view-node>
        </u-tree-view-node>
        <u-tree-view-node text="节点1.3"></u-tree-view-node>
        <u-tree-view-node text="节点1.4"></u-tree-view-node>
    </u-tree-view-node>
    <u-tree-view-node text="节点2"></u-tree-view-node>
    <u-tree-view-node text="节点3">
        <u-tree-view-node text="节点3.1" hidden></u-tree-view-node>
        <u-tree-view-node text="节点3.2"></u-tree-view-node>
    </u-tree-view-node>
</u-tree-view>
```

### 多选

通过`checkable`属性开启多选模式。

控制多选有两种方式，一种是设置数据各项的`checked`属性，该属性会与多项选择框进行双向绑定。`disabled`属性可以禁用多项选择框。

``` vue { width: 30% }
<template>
<u-tree-view ref="treeView" checkable :data="data"></u-tree-view>
</template>

<script>
export default {
    data() {
        return {
            data: [
                { text: '节点 1', expanded: true, checked: false, children: [
                    { text: '节点 1.1', expanded: false, checked: false },
                    { text: '节点 1.2', expanded: true, checked: false, children: [
                        { text: '节点 1.2.1', expanded: false, checked: false },
                        { text: '节点 1.2.2', expanded: false, checked: false },
                    ] },
                    { text: '节点 1.3', expanded: false, checked: false },
                    { text: '节点 1.4', expanded: false, checked: false },
                ] },
                { text: '节点 2', expanded: false, checked: false },
                { text: '节点 3', expanded: false, checked: false },
            ],
        };
    },
};
</script>
```

另一种是通过`:values.sync`对选择值进行双向绑定，该方法要求每项有`value`作为唯一值。`values`只会收集叶子节点的值。

``` vue { width: 30% }
<template>
<u-tree-view ref="treeView" checkable :values.sync="values" :data="data"></u-tree-view>
</template>

<script>
export default {
    data() {
        return {
            values: ['1.2.1', '1.2.2', '1.3', '3'],
            data: [
                { text: '节点 1', value: '1', expanded: true, checked: false, children: [
                    { text: '节点 1.1', value: '1.1', expanded: false, checked: false },
                    { text: '节点 1.2', value: '1.2', expanded: true, checked: false, children: [
                        { text: '节点 1.2.1', value: '1.2.1', expanded: false, checked: false },
                        { text: '节点 1.2.2', value: '1.2.2', expanded: false, checked: false },
                    ] },
                    { text: '节点 1.3', value: '1.3', expanded: false, checked: false },
                    { text: '节点 1.4', value: '1.4', expanded: false, checked: false },
                ] },
                { text: '节点 2', value: '2', expanded: false, checked: false },
                { text: '节点 3', value: '3', expanded: false, checked: false },
            ],
        };
    },
};
</script>
```

通过 `check-controlled` 属性开启节点状态完全受控，父子不关联。

``` vue { width: 30% }
<template>
<u-tree-view ref="treeView" check-controlled checkable :values.sync="values" :data="data"></u-tree-view>
</template>
<script>
export default {
    data() {
        return {
            values: ['1', '1.2', '1.2.1', '1.2.2'],
            data: [
                { text: '节点 1', value: '1', expanded: true, checked: false, children: [
                    { text: '节点 1.1', value: '1.1', expanded: false, checked: false },
                    { text: '节点 1.2', value: '1.2', expanded: true, checked: false, children: [
                        { text: '节点 1.2.1', value: '1.2.1', expanded: false, checked: false },
                        { text: '节点 1.2.2', value: '1.2.2', expanded: false, checked: false },
                    ] },
                    { text: '节点 1.3', value: '1.3', expanded: false, checked: false },
                    { text: '节点 1.4', value: '1.4', expanded: false, checked: false },
                ] },
                { text: '节点 2', value: '2', expanded: false, checked: false },
                { text: '节点 3', value: '3', expanded: false, checked: false },
            ],
        };
    },
};
</script>
```

### 其他方法

#### 统一操作

UTreeView 有针对选中/取消和展开/收起两个操作的统一处理的方法：`checkAll`和`toggleAll`，方便开发者使用。

``` vue { width: 30% }
<template>
<u-linear-layout direction="vertical">
    <u-tree-view ref="treeView" checkable :data="data"></u-tree-view>
    <u-linear-layout>
        <u-button @click="checkAll(true)">全部选中</u-button>
        <u-button @click="checkAll(false)">全部取消</u-button>
        <u-button @click="toggleAll(true)">全部展开</u-button>
        <u-button @click="toggleAll(false)">全部收起</u-button>
    </u-linear-layout>
</u-linear-layout>
</template>

<script>
export default {
    data() {
        return {
            data: [
                { text: '节点 1', expanded: true, checked: false, children: [
                    { text: '节点 1.1', expanded: false, checked: false },
                    { text: '节点 1.2', expanded: true, checked: false, disabled: true, children: [
                        { text: '节点 1.2.1', expanded: false, checked: false },
                        { text: '节点 1.2.2', expanded: false, checked: false },
                    ] },
                    { text: '节点 1.3', expanded: false, checked: false },
                    { text: '节点 1.4', expanded: false, checked: false },
                ] },
                { text: '节点 2', expanded: false, checked: false },
                { text: '节点 3', expanded: false, checked: false },
            ],
        };
    },
    methods: {
        checkAll(checked) {
            this.$refs.treeView.checkAll(checked);
        },
        toggleAll(expanded) {
            this.$refs.treeView.toggleAll(expanded);
        },
    },
};
</script>
```

#### 遍历和查找

UTreeView 有关于遍历与查找节点的方法：`walk`和`find`，方便开发者使用。

``` vue { width: 30% }
<template>
<u-linear-layout direction="vertical">
    <u-tree-view ref="treeView" :data="data"></u-tree-view>
    <u-linear-layout>
        <u-button @click="walk()">遍历所有节点</u-button>
        <u-button @click="find()">查找末尾为`4`的节点</u-button>
    </u-linear-layout>
</u-linear-layout>
</template>

<script>
export default {
    data() {
        return {
            data: [
                { text: '节点 1', expanded: true, checked: false, children: [
                    { text: '节点 1.1', expanded: false, checked: false },
                    { text: '节点 1.2', expanded: true, checked: false, disabled: true, children: [
                        { text: '节点 1.2.1', expanded: false, checked: false },
                        { text: '节点 1.2.2', expanded: false, checked: false },
                    ] },
                    { text: '节点 1.3', expanded: false, checked: false },
                    { text: '节点 1.4', expanded: false, checked: false },
                ] },
                { text: '节点 2', expanded: false, checked: false },
                { text: '节点 3', expanded: false, checked: false },
            ],
        };
    },
    methods: {
        walk() {
            // 注意：如果有返回值，遍历会终止。
            this.$refs.treeView.walk((nodeVM) => console.info(nodeVM.text));
        },
        find() {
            const nodeVM = this.$refs.treeView.find((nodeVM) => nodeVM.text.endsWith('4'));
            alert(nodeVM.text);
        },
    },
};
</script>
```

## UTreeView API
### Props/Attrs

| Prop/Attr | Type | Options | Default | Description |
| --------- | ---- | ------- | ------- | ----------- |
| data | Array\<{ text, value }\> |  |  | Data书写方式中的数据列表 |
| value.sync, v-model | any |  |  | 当前选择的值 |
| text-field | string |  | `'text'` | 选项文本的字段名 |
| value-field | string |  | `'value'` | 选项值的字段名 |
| cancelable | boolean |  | `false` | 是否可以取消选择 |
| checkable | boolean |  | `false` | 是否可以选中/取消 |
| accordion | boolean |  | `false` | 是否每次只会展开一个分组 |
| expand-trigger | string |  | `'click'` | 展开/折叠的触发方式。可选值：`'click'`表示整行点击均可触发、`'click-expander'`表示仅点击小箭头时触发 |
| readonly | boolean |  | `false` | 是否只读 |
| disabled | boolean |  | `false` | 是否禁用 |
| check-controlled | boolean |  | `false` | checkable 开启情况下，是否完全受控（父子节点状态不关联） |

### Slots

#### (default)

插入`<u-tree-view-node>`子组件

### Events

#### @before-select

选择某一项前触发

| Param | Type | Description |
| ----- | ---- | ----------- |
| $event.value | any | 选择项的值 |
| $event.oldValue | any | 旧的值 |
| $event.node | object | 选择项相关对象 |
| $event.oldNode | object | 旧的选择项相关对象 |
| $event.nodeVM | UTreeViewNode | 选择项子组件 |
| $event.oldVM | UTreeViewNode | 旧的选择项子组件 |
| $event.preventDefault | Function | 阻止选择流程 |
| senderVM | UTreeView | 发送事件实例 |

#### @input

选择某一项时触发

| Param | Type | Description |
| ----- | ---- | ----------- |
| $event | any | 选择项的值 |
| senderVM | UTreeView | 发送事件实例 |

#### @select

选择某一项时触发

| Param | Type | Description |
| ----- | ---- | ----------- |
| $event.value | any | 改变后的值 |
| $event.oldValue | any | 旧的值 |
| $event.node | object | 选择项相关对象 |
| $event.oldNode | object | 旧的选择项相关对象 |
| $event.nodeVM | UTreeViewNode | 选择项子组件 |
| $event.oldVM | UTreeViewNode | 旧的选择项子组件 |
| senderVM | UTreeView | 发送事件实例 |

#### @change

选择值改变时触发

| Param | Type | Description |
| ----- | ---- | ----------- |
| $event.value | any | 选择项的值 |
| $event.oldValue | any | 旧的值 |
| $event.node | object | 选择项相关对象 |
| $event.oldNode | object | 旧的选择项相关对象 |
| $event.nodeVM | UTreeViewNode | 选择项子组件 |
| $event.oldVM | UTreeViewNode | 旧的选择项子组件 |
| senderVM | UTreeView | 发送事件实例 |

#### @toggle

展开/折叠某节点时触发

| Param | Type | Description |
| ----- | ---- | ----------- |
| $event.expanded | boolean | 展开/折叠状态 |
| $event.node | object | 节点相关对象 |
| $event.nodeVM | UTreeViewNode | 节点组件 |
| senderVM | UTreeView | 发送事件实例 |

#### @check

选中/取消节点时触发

| Param | Type | Description |
| ----- | ---- | ----------- |
| $event.checked | boolean | 选中/取消状态 |
| $event.oldChecked | boolean | 旧的选中/取消状态 |
| $event.values | Array | 所有选中节点的值 |
| $event.node | object | 节点相关对象 |
| $event.nodeVM | UTreeViewNode | 节点组件 |
| senderVM | UTreeView | 发送事件实例 |

Methods

#### walk(func)

广度优先遍历树。当`func`函数有返回值时，停止遍历。

| Param | Type | Default | Description |
| ----- | ---- | ------- | ----------- |
| func | Function |  | 遍历的处理函数 |

#### find(func)

查找节点实例。

| Param | Type | Default | Description |
| ----- | ---- | ------- | ----------- |
| func | Function |  | 查找函数。找到第一个返回值为`true`的实例。 |

#### toggleAll(expanded)

展开/折叠所有节点

| Param | Type | Default | Description |
| ----- | ---- | ------- | ----------- |
| expanded | boolean |  | 展开/折叠 |

#### checkAll(checked)

选中/取消所有节点

| Param | Type | Default | Description |
| ----- | ---- | ------- | ----------- |
| expanded | boolean |  | 选中/取消 |

## UTreeViewNode API
### Props/Attrs

| Prop/Attr | Type | Options | Default | Description |
| --------- | ---- | ------- | ------- | ----------- |
| value | any |  |  | 此项的值 |
| expanded.sync | any |  |  | 展开/折叠状态 |
| checked.sync | any |  |  | 选中/取消状态 |
| disabled | boolean |  | `false` | 禁用此项 |
| node | object |  |  | 相关对象。当选择此项时，抛出的事件会传递该对象，便于开发 |

### Slots

#### (default)

插入文本或 HTML。

### Events

#### @before-select

选择此项前触发

| Param | Type | Description |
| ----- | ---- | ----------- |
| $event.value | any | 此项的值 |
| $event.node | object | 此项的相关对象 |
| $event.nodeVM | UTreeViewNode | 此组件 |
| $event.preventDefault | Function | 阻止选择流程 |
| senderVM | UTreeViewNode | 发送事件实例 |

#### @before-toggle

展开/折叠此节点前触发

| Param | Type | Description |
| ----- | ---- | ----------- |
| $event.expanded | boolean | 展开/折叠状态 |
| $event.node | object | 节点相关对象 |
| $event.nodeVM | UTreeViewNode | 节点组件 |
| $event.preventDefault | Function | 阻止展开/折叠流程 |
| senderVM | UTreeViewNode | 发送事件实例 |

#### @toggle

展开/折叠某节点时触发

| Param | Type | Description |
| ----- | ---- | ----------- |
| $event.expanded | boolean | 展开/折叠状态 |
| $event.node | object | 节点相关对象 |
| $event.nodeVM | UTreeViewNode | 节点组件 |
| senderVM | UTreeViewNode | 发送事件实例 |

#### @check

选中节点时触发

| Param | Type | Description |
| ----- | ---- | ----------- |
| $event.checked | boolean | 选中状态 |
| $event.oldChecked | boolean | 旧的选中状态 |
| $event.node | object | 节点相关对象 |
| $event.nodeVM | UTreeViewNode | 节点组件 |
| senderVM | UTreeViewNode | 发送事件实例 |

