Ant Design table 排序 ，點擊頭部只有升序和降序

state = {
    sortedInfo: {
        columnKey:'proportion',
        order:'descend'
    },
    saveSortedInfo:null
}

每列
const columns = [
    {
        title: '名稱',
        dataIndex: 'name',
        key: 'name',
        className:'t_center',
        width:'120px'
    },
    {
        title: '占比',
        dataIndex: 'proportion',
        key: 'proportion',
        className:'t_center',
        sorter: (a, b) => a.proportion - b.proportion,
        defaultSortOrder:'descend',
        sortDirections: [ 'descend','ascend'],  
        sortOrder: sortedInfo.columnKey === 'proportion' && sortedInfo.order,
     
    },
　　{....},{...}
]

//變化事件

function has_value(data){
    return Object.keys(data).length>0
}

handleChange = (pagination, filters, sorter) => {
    if(has_value(sorter)){  //判斷sorter 是否為null ,我用的是Object.keys(obj).length 
        this.setState({
            sortedInfo: sorter,
            saveSortedInfo: sorter   //保存此次點擊的對象
        });
    }else{
        this.setState({
            sortedInfo:{
                order:this.state.saveSortedInfo.order=='ascend'?'descend':'ascend',
                columnKey:this.state.saveSortedInfo.columnKey
            }
        })
    }



}