我在将数据发布到我fetch在 react-native 应用程序中使用的快速 REST API 时遇到问题。这是我的代码：

/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 * @flow
 */

import React, { Component } from 'react';
import {
  AppRegistry,
  StyleSheet,
  Text,
  View
} from 'react-native';
import Button from 'react-native-button';
import DeviceInfo from 'react-native-device-info'

export default class ReliefMobile extends Component {
  state: any;

  constructor(props) {
    super(props);
    this.state = {
      currentLocation: {latitude: 40.6391, longitude: 10.9969},
      name: 'Some dumb name',
      description: 'Some dumb description',
      deviceId: DeviceInfo.getUniqueID()
    }
  }

  addData() {
    fetch('http://localhost:3000/api/effort/add', {
      method: 'POST',
      headers: {
        'Accept': 'application/json',
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({
        name: this.state.name,
        description: this.state.description,
        deviceId: this.state.deviceId,
        currentLocation: this.state.currentLocation
      })
    });
  }

  render() {
    return (
      <View style={styles.container}>
        <Text style={styles.welcome}>
          Welcome to React Native
        </Text>
        <Text style={styles.instructions}>
          Your device ID is {DeviceInfo.getUniqueID()}
        </Text>
        <Text style={styles.instructions}>
        Effort Name: {this.state.name}
        </Text>
        <Text style={styles.instructions}>
        Effort Description: {this.state.description}
        </Text>
        <Text style={styles.instructions}>
        Location: {this.state.currentLocation.latitude}, {this.state.currentLocation.longitude}
        </Text>
        <Button onPress={this.addData}>Add data</Button>
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#F5FCFF',
  },
  welcome: {
    fontSize: 20,
    textAlign: 'center',
    margin: 10,
  },
  instructions: {
    textAlign: 'center',
    color: '#333333',
    marginBottom: 5,
  },
});

AppRegistry.registerComponent('ReliefMobile', () => ReliefMobile);

当我尝试按我的按钮来调用addData函数，我得到这个错误：undefined is not an object (evaluating this.state.name)。

在应用程序加载时，我的状态变量似乎加载到了以下<Text/>区域：

但是当我提交时，这是显示：

当我改变的身体fetch是一样的东西

body: JSON.stringify({name: 'some name', description: 'some description'})

它工作正常。所以我认为函数this内部的值可能不一样fetch，所以在顶部addData()我做了一些类似的事情let that = this;并将我的所有状态变量设置为that.state.name, etc但仍然不起作用。