无法读取未定义 REACT 的属性“地图"
构造函数(){极好的();这个.state = {清单:[],}}组件DidMount(){fetch('http://lospraianos-env-1.qu3skpxsmw.sa-east-1.elasticbeanstalk.com/api/materials').then(response => response.json()).then(resData => {this.setState({data: resData.results});})}<table className="纯表"><头><tr><th>id</th><th>产品</th><th>Quantidade</th></tr></头><身体>{this.props.lista.map(函数(数据){返回 (<tr 键={data.codMat}><td>{data.codMat}</td><td>{data.material}</td><td>{data.qntMin}</td></tr>);})}</tbody></表></div>
我正在尝试从 API 获取信息并使用它制作一个表格,但我遇到了一些错误.
<块引用>无法读取未定义的属性地图"
我该如何处理?
解决方案您正在设置对代码中不存在的状态变量数据的响应.您需要将其设置为 lista 而不是 fetch Api 调用中的数据,例如
this.setState({lista : resData.results});
在这里做条件检查和做.map
.map 没有返回
<tbody>{this.props.lista &&this.props.lista.map(数据 => (<tr 键={data.codMat}><td>{data.codMat}</td><td>{data.material}</td><td>{data.qntMin}</td></tr>))}</tbody>
.map 带返回
<tbody>{this.props.lista &&this.props.lista.map(data => {return (constructor(){
super();
this.state = {
lista: [],
}
}
componentDidMount(){
fetch('http://lospraianos-env-1.qu3skpxsmw.sa-east-1.elasticbeanstalk.com/api/materials')
.then(response => response.json())
.then(resData => {
this.setState( {data: resData.results});
})
}
<div>
<table className="pure-table">
<thead>
<tr>
<th>id</th>
<th>Produto</th>
<th>Quantidade</th>
</tr>
</thead>
<tbody>{
this.props.lista.map(function(data){
return (
<tr key={data.codMat}>
<td>{data.codMat}</td>
<td>{data.material}</td>
<td>{data.qntMin}</td>
</tr>
);
})
}
</tbody>
</table>
</div>
I'm trying to get info from the API and make a table with it but I'm getting some errors.
Cannot read property 'map' of undefined
how can I deal with it?
解决方案 You are setting response to a state variable data which doesn’t exist in your code. You need to set it to lista instead of data in fetch Api call like
this.setState({lista : resData.results});
And here do conditional check and do .map
.map without return
<tbody>{
this.props.lista && this.props.lista.map(data => (
<tr key={data.codMat}>
<td>{data.codMat}</td>
<td>{data.material}</td>
<td>{data.qntMin}</td>
</tr>
))
}
</tbody>
.map with return
<tbody>{
this.props.lista && this.props.lista.map(data => {
return (<tr key={data.codMat}>
<td>{data.codMat}</td>
<td>{data.material}</td>
<td>{data.qntMin}</td>
</tr>)
})
}
</tbody>
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