RenderItems 未定义 no-undef 内返回

Question

Hello Guys 是 reactjs 的新手，我正在尝试获取响应数据对象，以便能够在 webapp 上显示以供用户查看，而不是检查页面并转到网络/控制台查看文件上传错误响应name= 'title' 所以我决定使用下面的函数来给我数据响应，我不断收到这个错误 'renderItems is not defined' no-undef 下面是示例代码：

import React from "react";
import PropTypes from "prop-types";
import axios from 'axios'
import { Card,} from "shards-react";

class Uploaddatastore extends React.Component {

  constructor(props) {
    super(props);

    this.state = {
      UploadNotification: []
    }
  }
  componentDidMount(){
    let notificationComponent = this;
    axios.get("http://127.0.0:8000/uploads/file_upload/")
      .then(function (response) {
        console.log(response);
        console.log(response.data);

        notificationComponent.setState({
          UploadNotification: response.data.items
        });

      })
      .catch(function (error) {
        console.log(error);
      });
  }
render() {
      if (this.state.UploadNotification.length) {
        let renderItems = this.state.UploadNotification.map(function(item, i) {
          return <li key={i}>{item.title}</li>
        });
      }
    return (
     <div>
       <span className="text-danger"> {renderItems} </span>
     </div>
    );
  }
};
export default Uploaddatastore;

Answer 1

您对 renderItems 变量的范围错误。它仅限于if 块。在 if 之前声明它：

render() {
    let renderItems;
    if (this.state.UploadNotification.length) {
      renderItems = this.state.UploadNotification.map(function(item, i) {
          return <li key={i}>{item.title}</li>
      });
    }
    return (
     <div>
       <span className="text-danger"> {renderItems} </span>
     </div>
    );
  }
};