Element-UI中<el-cascader />回显失败问题的完美解决

depart_check: [],
options: [
	{
	    value: 1,
	    label: '东南',
	    children: [
	    	{
		        value: 11,
		        label: '上海',
		        children: [{
		            value: 111,
		            label: '黄浦区'
		        }, {
		            value: 112,
		            label: '静安区'
		        }, {
		            value: 113,
		            label: '虹口区'
		        }, {
		            value: 114,
		            label: '长宁区'
		        }]
		    }, {
		        value: 12,
		        label: '江苏',
		    }, {
		        value: 13,
		        label: '浙江',
		    }
	    ]
	}, 
	{
	    value: 2,
	    label: '西北',
	    children: [{
	        value: 21,
	        label: '陕西',
	    }, {
	        value: 22,
	        label: '新疆维吾尔族自治区',
	    }]
	}
]

/*
* @param  list 数据列表
* @param  id 后端返回的id
**/
getParentsById(list, id) {
    for (let i in list) {
        if (list[i].value == id) {
            //查询到就返回该数组对象的value
            return [list[i].value]
        }
        if (list[i].children) {
            let node = this.getParentsById(list[i].children, id)
            if (node !== undefined) {
                //查询到把父节把父节点加到数组前面
                node.unshift(list[i].value)
                return node
            }
        }
    }
},

// 选择单位
  handlechangedepatt(v) {
  	  console.log(v)
      this.depart_check = v
  },

	let _depart_check = data.depart_id ? data.depart_id.split(",").map(i => Number(i)) : []
	let _arr = []
	// 使用上面写的方法 getParentsById 找出父级id并组合
	_depart_check && _depart_check.map(i => _arr.push(this.getParentsById(this.options, i)))
	console.log("_arr: ",_arr)
	this.depart_check = _arr

	let _depart_check = data.depart_id || ""
	let _arr = []
	_arr = this.getParentsById(this.options, _depart_check )
	this.depart_check = _arr