React component fails on react-pull-to-refresh

Question

I have a fairly simple ASP.NET site with a react front-end. It has a component MetaWeatherForecast that fetches some data from an API endpoint and displays it in a table. That works fine.

After pulling in react-pull-to-refresh into the project and attaching it to the component, the table initially loads and fetches the data on the first load, but then fails as soon as I pull the table to refresh.

Here's a trimmed version of the component in its current form:

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>
        );
    }
};

The error being thrown after pulling the table is as follows and is thrown inside the handleRefresh() method:

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

Any ideas or suggestions would be most welcome

Answer 1

In react classes, you have to bind this in the constructor

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

I like using this library.