vue element table expand 扩展行点击行展示且保证只展示一行

背景：因为element里面的扩展行支持多行展示扩展行，但接到了需求，只能展示一行，如：第一行扩展，点击第二行的时候，第一行收起，第二行展开。同时改成点击行展示扩展内容

<el-table
        :data="eventTableData"
        style="width: 100%"
        @cell-click="clickTable"
        ref="refTable"
        @selection-change="handleSelectionChange"
        @expand-change="expandSelect"
       >
<el-table-column type="expand"  width="0px" label="扩展">

</el-table-column>

</el-table>

data:{

eventTableData:[],

expands:[],

}

methods:{

clickTable:function(row, column, cell, event){//展开事件日志列表
    if(cell.cellIndex!=3 && cell.cellIndex!=10){
        this.$refs.refTable.toggleRowExpansion(row);
    }
    this.getnoTicketReason("",row.businessType);
},
handleSelectionChange:function (val) {
console.log(val)
},
expandSelect:function (row, expandedRows) {
    var that = this
    if (expandedRows.length>1) {
        that.expands = []
        if (row) {
            that.expands.push(row);
        }
        this.$refs.refTable.toggleRowExpansion(expandedRows[0]);
    } else {
        that.expands = [];
    }
},

}