<template>
  <div>
	<a-tree-select
		labelInValue
		style="width: 20%"
		:dropdown-style="{ maxHeight: '400px', overflow: 'auto' }"
		:tree-data="treeData"
		 placeholder="Please select"
		@select="selectTree"
		:value="treeValue"
		 tree-default-expand-all
		 >
	</a-tree-select>
  </div>
</template>

<script>
const treeData = [
  {
    title: 'father1',
    value: '0',
    key: '0',
    children: [
    {
		title: 'Child1',
        value: '0-1',
        key: '0-1',
		children: [
			{
				title: 'Child1-1',
				value: '0-1-1',
				key: '0-1-1'
			},
			{
				title: 'Child1-2',
				value: '0-1-2',
				key: '0-1-2',
			},
		],
     },
     {
        title: 'Child2',
        value: '0-2',
        key: '0-2',
      },
    ],
  },
  {
    title: 'father2',
    value: '1',
    key: '1',
  },
];
export default {
  data() {
    return {
      	treeValue: {
			label: 'father1',
			value: '0'
		},
      	treeData,
		title: '',
		defaultTitle: ''
    };
  },
	created() {
		this.setTitle('0-1')
	},
	methods:{
		/**
		 * @description 设置当前选中对象
		 */
		setTitle(title){
			this.getSelectedItem(title, this.treeData)
			this.$nextTick(()=>{
				this.treeValue = {
					label: this.defaultTitle,
					value: title
				}
			})
		},
		/**
		 * @description 当前选中对象的title(拼接所有父级title)
		 */
		getSelectedItem(value, data, title){
			for(let item of data){
				//在根节点找到对应选项
				if (!title && item.value == value ) {
					this.defaultTitle = item.title
				} 
				//根节点未找到继续递归查找
				else if(!title && item.children){
					this.defaultTitle = item.title 
				 	this.getSelectedItem(value, item.children, this.defaultTitle);
				}
				
				//在子节点找到对应选项
				if (title && item.value == value){
					this.defaultTitle = title + '-' + item.title
				}
				//当前子节点未找到继续递归向下查找
				else if(title && item.children){
					this.defaultTitle = title + '-' + item.title
				  	this.getSelectedItem(value, item.children, this.defaultTitle);
				}
			}
		},
		/**
		 * @description 选择节点触发
		 */
		selectTree(nodeValue){
			this.setTitle(nodeValue.value)
		}
	}
};
</script>

<style scoped>

</style>
</template>