在编写树形组件时遇到的问题：
- 组件如何才能递归调用？
- 递归组件点击事件如何传递？
2、树形控件基本结构及样式
<template>
<ul class="vue-tree">
<li class="tree-item">
<div class="tree-content"><!--节点内容-->
<div class="expand-arrow"></div><!--展开或收缩节点按钮-->
<div class="tree-label">小学</div><!--节点文本内容-->
</div>
<ul class="sub-tree"><!--子节点-->
<li class="tree-item expand">
<div class="tree-content">
<div class="expand-arrow"></div>
<div class="tree-label">语文</div>
</div>
</li>
<li class="tree-item">
<div class="tree-content">
<div class="expand-arrow"></div>
<div class="tree-label">数学</div>
</div>
</li>
</ul>
</li>
</ul>
</template>
<style lang="stylus">
.vue-tree{
list-style: none;
padding: 0;
margin: 0;
.tree-item{
cursor: pointer;
transition: background-color .2s;
.tree-content{
position: relative;
padding-left: 28px;
&:hover{
background-color: #f0f7ff;
}
}
.expand-arrow{
position: absolute;
top: 0;
left: 0;
width: 28px;
height: 28px;
cursor: pointer;
&::after{
position: absolute;
top: 50%;
left: 50%;
display: block;
content: ' ';
border-width: 5px;
border-style: solid;
border-color: transparent;
border-left-color: #ccc;
margin: -5px 0 0 -2.5px;
transition: all .2s;
}
}
&.expand{
&>.tree-content{
background-color: #f0f7ff;
&>.expand-arrow{
&::after{
transform: rotate(90deg);
margin: -2.5px 0 0 -5px;
}
}
}
}
.tree-label{
height: 28px;
line-height: 28px;
font-size: 14px;
}
.sub-tree{
display: none;
list-style: none;
padding: 0 0 0 28px;
margin: 0;
}
&.expand>.sub-tree{
display: block;
}
&.no-child{
&>.tree-content{
&>.expand-arrow{
display: none;
}
}
}
}
}
</style>
3、组件目录及数据结构
目录结构
vue-tree
vuetree.vue
treeitem.vue
树形控件数据结构
let treedata = [
{
text: "一级", // 显示的文字
expand: false, // 默认是否展开
children: [ // 子节点
{
text: "一级-1",
expand: false,
},
{
text: "一级-2",
expand: false,
children: [
{
text: "一级-2-1",
expand: false,
},
{
text: "一级-2-2",
expand: false,
}
]
}
]
}
];
3.1、 treeitem.vue 代码
<template>
<li class="tree-item" :class="{expand: isexpand, 'no-child': !treeitemdata.children || treeitemdata.children.length === 0}">
<div class="tree-content" @click="_clickevent">
<div class="expand-arrow" @click.stop="expandtree()"></div>
<div class="tree-label">{{treeitemdata.text}}</div>
</div>
<ul class="sub-tree" v-if="treeitemdata.children && treeitemdata.children.length > 0">
<!--treeitem组件中调用treeitem组件-->
<treeitem
v-for="item in treeitemdata.children"
:tree-item-data="item"
:key="uuid()"
:tree-click-event="treeclickevent"></treeitem>
</ul>
</li>
</template>
<script>
export default {
name: "treeitem",
props: {
treeitemdata: {
type: object,
default(){
return {};
}
},
// 节点点击事件
treeclickevent: {
type: function,
default() {
return function () {};
}
}
},
data(){
return {
// 节点是否展开
isexpand: this.treeitemdata.expand || false
}
},
methods: {
// 展开/收缩
expandtree(flag){
if(!this.treeitemdata.children || this.treeitemdata.children.length === 0){
return;
}
if(typeof flag === 'undefined'){
flag = !this.isexpand;
}else{
flag = !!flag;
}
this.isexpand = flag;
},
// 创建一个唯一id
uuid(){
let str = math.random().tostring(32);
str = str.substr(2);
return str;
},
// 节点点击事件
_clickevent(){
// 如果有传递事件函数，则调用事件函数并传递当前节点数据及组件
if(this.treeclickevent && typeof this.treeclickevent === 'function'){
this.treeclickevent(this.treeitemdata, this);
}
}
}
}
</script>
3.1.1、解决 组件如何才能递归调用？ 问题
在组件模板内调用自身 必须明确定义组件的name属性 ，并且递归调用时组件名称就是name属性。如在 treeitem.vue 组件中组件的name名称为'treeitem'，那么在template中调用时组件名称就必须是 <treeitem> 。
当然也可以全局注册组件，具体可以查看vue官方文档 递归组件
3.1.2、解决 递归组件点击事件如何传递？ 问题
我这里的解决方案是使用 props 将事件函数传递进来，在点击节点的时候调用事件函数，并把相应的数据传递进去。
之前也尝试过使用 $emit 的形式并把数据传递过去，由于是递归组件，这样一直 $emit ，到最外层时传递的数据就变了，比如传递是第3层节点的数据，到最后执行时数据就变成第1层节点的数据了
4、 vuetree.vue 组件
<template>
<ul class="vue-tree">
<treeitem
v-for="(item, index) in treedata"
:key="index"
:treeitemdata="item"
:tree-click-event="treeclickevent"></treeitem>
</ul>
</template>
<script>
import treeitem from "./treeitem";
export default {
name: "vuetreemenu",
components: {
treeitem
},
props: {
// 树形控件数据
treedata: {
type: array,
default(){
return [];
}
},
// 节点点击事件
treeclickevent: {
type: function,
default() {
return function () {};
}
}
}
}
</script>
<style lang="stylus">
.vue-tree{
list-style: none;
padding: 0;
margin: 0;
.tree-item{
cursor: pointer;
transition: background-color .2s;
.tree-content{
position: relative;
padding-left: 28px;
&:hover{
background-color: #f0f7ff;
}
}
.expand-arrow{
position: absolute;
top: 0;
left: 0;
width: 28px;
height: 28px;
cursor: pointer;
&::after{
position: absolute;
top: 50%;
left: 50%;
display: block;
content: ' ';
border-width: 5px;
border-style: solid;
border-color: transparent;
border-left-color: #ccc;
margin: -5px 0 0 -2.5px;
transition: all .2s;
}
}
&.expand{
&>.tree-content{
background-color: #f0f7ff;
&>.expand-arrow{
&::after{
transform: rotate(90deg);
margin: -2.5px 0 0 -5px;
}
}
}
}
.tree-label{
height: 28px;
line-height: 28px;
font-size: 14px;
}
.sub-tree{
display: none;
list-style: none;
padding: 0 0 0 28px;
margin: 0;
}
&.expand>.sub-tree{
display: block;
}
&.no-child{
&>.tree-content{
/*padding-left: 0;*/
&>.expand-arrow{
display: none;
}
}
}
}
}
</style>
5、使用树形组件
<template>
<div class="app" id="app">
<vuetree :tree-data="treedata2" :tree-click-event="treeclickevent"></vuetree>
</div>
</template>
<script>
import vuetree from "./components/vue-tree/vuetree";
export default {
name: 'app',
data(){
return {
treedata2: [
{
text: "一级", // 显示的文字
expand: false, // 默认是否展开
children: [
{
text: "二级-1",
expand: false,
},
{
text: "二级-2",
expand: false,
children: [
{
text: "三级-1",
expand: false,
},
{
text: "三级-2",
expand: false,
children: [
{
text: "四级-1",
expand: false,
}
]
}
]
}
]
},
{
text: "一级-2",
expand: false
}
]
}
},
methods: {
treeclickevent(item, treeitem){
console.log(item);
}
},
components: {
vuetree
}
}
</script>
总结
