Javascript TypeError:无法读取属性';地图';数组中未定义状态对象的类型?
数组顺序中的状态对象\u转换映射错误Javascript TypeError:无法读取属性';地图';数组中未定义状态对象的类型?,javascript,arrays,json,reactjs,undefined,Javascript,Arrays,Json,Reactjs,Undefined,数组顺序中的状态对象\u转换映射错误 this.state = { order: { "id": 2, "order_trans": [ { "id": 2, "order_payment_id": "61023184-4ee7-4b8d-80c7-b593b994607f&quo
this.state = {
order: {
"id": 2,
"order_trans": [
{
"id": 2,
"order_payment_id": "61023184-4ee7-4b8d-80c7-b593b994607f",
"order_amount": 11628.0,
"signature": "TSbSYzqNcT3PD7sgu4KGpuTsgIPzumTeg753iswBGsw=",
"created_at": "2020-10-29T16:13:22.158603Z",
"updated_at": "2020-10-29T16:13:22.158630Z",
"buyer": 20,
"order": 2
}
],
"order_token": "61023184-4ee7-4b8d-80c7-b593b994607f",
"grand_total": 11628.0,
"name": "Achu",
"land_mark": "",
"created_at": "2020-10-29T16:12:31.291014Z",
"updated_at": "2020-10-29T16:12:31.291035Z",
"buyer": 20
}
}
当在状态对象数组中循环时
{this.state.order.order_trans.map((p) => (
<p>{p.id}</p>
))}
{this.state.order.order_trans.map((p)=>(
{p.id}
))}
我得到错误类型错误:无法读取未定义的属性“map”我认为您正在渲染后更新状态。在这种情况下,只需确保状态中存在
order\u trans
值。您可以执行以下操作:
{this.state.order && this.state.order.order_trans && this.state.order.order_trans.map((p) => (
<p>{p.id}</p>
))}
{this.state.order&&this.state.order.order\u trans&&this.state.order.order\u trans.map((p)=>(
{p.id}
))}
或者您可以使用新的可选链接操作符
{ this.state.order?.order_trans.map((p) => (
<p>{p.id}</p>
))}
{this.state.order?.order\u trans.map((p)=>(
{p.id}
))}
看起来正确。您能提供更多信息吗?请尝试this.state.order?.order\u trans?.map