React 组件在 react-pull-to-refresh 时失败

Question

我有一个相当简单的 ASP.NET 网站，带有 React 前端。它有一个组件 MetaWeatherForecast，它从 API 端点获取一些数据并将其显示在 table 中。效果不错。

将 react-pull-to-refresh 拉入项目并将其附加到组件后，table 最初在第一次加载时加载并获取数据，但在我拉 table刷新。

这是当前形式的组件的精简版：

MetaWeatherForecast.js

import React, { Component } from 'react';
import authService from './api-authorization/AuthorizeService'
import Moment from 'moment';
import ReactPullToRefresh from 'react-pull-to-refresh'

export class MetaWeatherForecast extends Component {

    static displayName = MetaWeatherForecast.name;

  constructor(props) {
    super(props);
      this.state = {
          locationForecast: {}, loading: true, success: true, errorMessage: null };
  }

  componentDidMount() {
    this.populateWeatherData();
  }

    static renderForecastsTable(locationForecast) {
            // html markup for the table
    }

    static renderError(errorMessage) {
        // error markup
    }

    handleRefresh(resolve, reject) {  

        let success = this.populateWeatherData();

        if (success)
            resolve();
        else
            reject();        
    }

    async populateWeatherData() {

        this.setState({ locationForecast: {}, loading: true, success: true, errorMessage: null});

        const token = await authService.getAccessToken();

        const response = await fetch('api/metaweatherforecast/GetFiveDayForecast/44544', {
            headers: !token ? {} : { 'Authorization': `Bearer ${token}` }
        });

        const baseResponse = await response.json();

        console.log(baseResponse);

        this.setState({ locationForecast: baseResponse.data, loading: false, success: baseResponse.success, errorMessage: baseResponse.errorMessage });

        return baseResponse.success;
    }

    getContent() {

        let contents;

        if (this.state.loading) {
            contents = <p><em>Fetching forecast...</em></p>
        } else {
            contents = this.state.success
                ? MetaWeatherForecast.renderForecastsTable(this.state.locationForecast)
                : MetaWeatherForecast.renderError(this.state.errorMessage);
        }

        return contents;
    }

  render() {   

      return (
          <ReactPullToRefresh
              onRefresh={this.handleRefresh}
              style={{
                  textAlign: 'center'
              }}>                
              <div>
                <p><em>Pull down to refresh</em></p>
                <h1 id="tabelLabel" >Meta Weather forecast</h1>
                  {this.getContent()}
              </div>
          </ReactPullToRefresh>
        );
    }
};

拉table后抛出的错误如下，在handleRefresh()方法内部抛出：

Uncaught (in promise) TypeError: this.populateWeatherData is not a function

欢迎提出任何想法或建议

Answer 1

在 React 类 中，你必须在构造函数中绑定 this

constructor(props) {
    ...
    this.<method> = this.<method>.bind(this);
}

我喜欢用this library。