React组件在react拉-to-刷新上失败。

Question

我有一个相当简单的ASP.NET站点与一个反应前端。它有一个组件MetaWeatherForecast，它从一个API端点获取一些数据并将其显示在一个表中。效果很好。

在将反应-拉动-刷新导入项目并将其附加到组件后，表最初在第一次加载时加载和获取数据，但在我拉出表刷新后立即失败。

下面是该组件当前形式的修整版本：

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>
        );
    }
};

在拉动表后引发的错误如下所示，并在handleRefresh()方法中引发：

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

欢迎您提出任何意见或建议。

Answer 1

在react类中，必须在构造函数中绑定this。

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

我喜欢使用这个图书馆。