<el-select v-model="value" multiple placeholder="請選擇" :popper-append-to-body="false"
    @remove-tag="removetag"  collapse-tags @clear="clearall" clearable >
    <el-option :value="selectTree" class="setstyle" disabled>
		<el-tree :data="list" :props="defaultProps" ref="tree"
		show-checkbox check-strictly :expand-on-click-node="false" node-key="id"
		check-on-click-node @check-change="handleNodeClick"></el-tree>
	</el-option>
</el-select>

<script>
	export default {
		data() {
			return {
				value:[],
				selectTree:[],
				defaultProps:{
					children: 'children',
					label: 'label'
				},
				list: [{
					id: 1,
					label: '一級 2',
					children: [{
						id: 3,
						label: '二級 2-1',
						children: [{
							id: 4,
							label: '三級 3-1-1'
						}, {
							id: 5,
							label: '三級 3-1-2',
						}]
					}, {
						id: 2,
						label: '二級 2-2',
						children: [{
							id: 6,
							label: '三級 3-2-1'
						}, {
							id: 7,
							label: '三級 3-2-2',
						}]
					}]
				}],
			}
		},
		methods: {
			handleNodeClick(data,self,child) {
				console.log(this.$refs.tree.getCheckedNodes())
				let datalist = this.$refs.tree.getCheckedNodes()
				this.selectTree = [] //置空
				this.value = []
				datalist.forEach((item)=>{
					this.selectTree.push({id:item.id,label:item.label})
					this.value.push(item.label)
				})
			},
            removetag(){
				this.selectTree.splice(0,1)
				let setlist = this.$refs.tree.getCheckedNodes()
				setlist.splice(0,1)
				this.$nextTick(() => {
					this.$refs.tree.setCheckedNodes(setlist) 
				})
			},
			clearall(){
				this.selectTree = []
				this.$nextTick(() => {
					this.$refs.tree.setCheckedNodes([]) 
				})
			},
		},
	}
</script>

.setstyle {
	min-height: 200px;
	padding: 0 !important;
	margin: 0;
	overflow: auto;
	cursor: default !important;
}