this.setState不是函数，本机反应

Question

It is telling me this.setState' is undefined, but i'm not sure what I can do to make "this" refer to the proper context for setState. I don't know what else I can bind to help.

 import React from 'react';
 import { StyleSheet, Text, View } from 'react-native';
 import axios from 'react-native-axios';

 export default class App extends React.Component {
   constructor(props) {
   super(props);
   this.state = {
     data: 50
   }
   this.apirequest = this.apirequest.bind(this);
 }

  componentWillMount() {
    this.apirequest();
  }

  apirequest() { 

    axios.get('http://api.openweathermap.org/data/2.5/weather')
    .then(function (response) {
      console.log(response.data.main.temp);
      this.setState({
         data: response.data.main.temp 
       })
    })
   .catch(function (error) {
     console.log(error);
    });
}

Answer 1

Use arrow function inside the then block to stay in the scope:

.then(response => {
  this.setState({
     data: response.data.main.temp 
   })
})

Answer 2

Try replacing your function by using a ES6 fat arrow function

instead of

.then(function (response) {...

do

.then(response => { ...

This works because fat arrow functions do not redefine the definition of this , therefore the value of this is still the originating context