Question

enter code here我想从profilesProject内的'for'循环（qualityPname）中检索一个String变量（componentDidMount()），但它甚至没有进入使用'for'循环运行。

循环工作正常，连接文本因为我在导出函数中测试。

有些线索我做错了什么？提前谢谢。

import React from 'react';
import .... from ...

export default class MPApp extends React.PureComponent {
  state = {
    name: '',
    profilesProject: '',
  };
  componentDidMount() {
    findQG(this.props.project).then(
      (valuesReturnedByAPI) => {
        this.setState({
          name: valuesReturnedByAPI
        });
      }
    );
    qualityPname(project) {
      const numberQP = project.qp.length;
      var profilesProject = " ";
      if (numberQP > 0) {
        for (var k = 0; k < numberQP; k++) {
          profilesProject = project.qp[k].n + " (" + project.qp[k].l + ")  ";
          console.log(project.qp[k].n);
          console.log(project.qp[k].l);
        }
        console.log(profilesProject);
        return profilesProject; //String I want to retun 
      }
      return ("N/A"); //You should return something in that case also.
    }
  }
  render() {
    return (
      <div className="page page-limited">
        <table >
          <tbody>
            <tr>
              <td>QP: {this.state.profilesProject} </td> //here I want to bring the string
            </tr>
            <tr>
              <td>QG: {this.state.name} </td>
            </tr>
          </tbody>
        </table>
      </div>
    );
  }
}

ANSWER1之后的DEV ENV中的错误 - Git bash

Failed to Compile

Error in ./src/main/js/components/MeasuresProjectApp.js
Syntax error: D:/Userfiles/Expression/plugin-example/src/main/js/components/MeasuresProjectApp.js: Unexpected token, expected ; (53:21)

  51 |
  52 |
> 53 | qualityPname(project){
     |                      ^
  54 |
  55 |                          const numberQP = project.qp.length;
  56 |                          console.log(numberOfQualityP);

 @ ./src/main/js/app-measures_project.js

Answer 1

您不希望从函数返回值，您想要使用该值设置状态。试试这个：

    componentDidMount() {
        findQG(this.props.project).then(
          (valuesReturnedByAPI) => {
            this.setState({
              name: valuesReturnedByAPI
            });
          }
        );
        qualityPname(project) {
          const numberQP = project.qp.length;
          var profilesProject = " ";
          if (numberQP > 0) {
            for (var k = 0; k < numberQP; k++) {
              profilesProject = project.qp[k].n + " (" + project.qp[k].l + ")  ";
              console.log(project.qp[k].n);
              console.log(project.qp[k].l);
            }
            console.log(profilesProject);
            this.setState({ profilesProject })
          }
          this.setState({ profilesProject: 'N/A' })
        }
      }

React JS：如何使用componentDidMount（）从函数中检索字符串变量

1 个答案: