不变暴力预期字符串，获取对象-从回显字符串的php页面

Question

我对React Native非常陌生。我正在登录用户。这是我要去的tutorial。我不得不使用XMLHttpRequest而不是fetch，因为我无法使其正确传递POST参数。它发布的PHP页面只是在返回之前回显了userID。它没有返回json字符串或任何东西。

我正在登录用户并使用

this.setState({ userID: request.responseText });

跟踪用户ID。这行代码给我带来了Invariant Violation错误，它期望一个字符串，而我给它一个对象。

App.js（如果您看到任何明显的答案，我会添加注释掉的提取内容

import React, { Component } from 'react'
import { View, Text,  Alert, Button, TextInput, TouchableOpacity } from 'react-native';
import Home from './Home';
export default class App extends Component{
  state = {
    email: '',
    pwd: '',
    auth_token: '',
    userID: ''
  }

  Login = async () => {
      var request = new XMLHttpRequest();
      var params = "email=" + this.state.email + "&pwd=" + this.state.pwd;
      request.onreadystatechange = (e) => {
    if (request.readyState !== 4) {
        return;
    }

  if (request.status === 200) {
    console.log('success', request.responseText);  
    Alert.alert(request.responseText); //this is returning the correct value
    if(request.responseText != "ERROR"){
       this.setState({ userID: request.responseText });
       Alert.alert("Welcome", " You have succesfully logged in");//also returning
    }else{
        Alert.alert("Oh, no!", " There was a problem");
    }
  } else {
    console.warn('error');
  }
};

request.open('POST', 'https://mysitexzy.com/wLoginCE');
request.send(params);
/*
    fetch('https://mysitexzy.com/wLoginCE', {
          method: 'post',
          headers: {
            Accept: 'application/json',
   // 'Content-Type': 'application/json',
          },
          body: JSON.stringify({
  //          "provider": "username",
            "email": this.state.email,
            "pwd": this.state.pwd

          })
        }).then((response) => response.json())
        .then((res) => {
      if(typeof(res.message) != "undefined"){
       Alert.alert("Error", "Error: "+ res.message);
      }
      else{
        this.setState({ userID: response });
        Alert.alert("Welcome", " You have succesfully logged in");
        }
     }).catch((error) => {
         console.error(error);
        });
        */
  }
  render(){
  //If auth token is not present
   if(this.state.userID==''){
     return(
     <View style={{
        flex: 1,
        flexDirection: 'column',
        justifyContent: 'center',
        alignItems: 'stretch',
      }}>
     <TextInput
           placeholder="Enter User name"
           onChangeText={ TextInputValue =>
           this.setState({email : TextInputValue }) }
           underlineColorAndroid='transparent'
           style={
           {
               textAlign: 'center',
               width: '90%',
               marginBottom: 7,
               height: 40,
               borderRadius: 5 ,
               fontSize: 20,
           }
         }
         />
     <TextInput
           placeholder="Enter password"
           onChangeText={ TextInputValue =>
           this.setState({pwd: TextInputValue }) }
           underlineColorAndroid='transparent'
           secureTextEntry={true}
           style={
           {
               textAlign: 'center',
               width: '90%',
               marginBottom: 7,
               height: 40,
               borderRadius: 5 ,
               fontSize: 20,
           }
         }
         />
        <TouchableOpacity onPress={this.Login.bind(this)}>
        <View style={{height: 50, backgroundColor:
        '#cc0066',justifyContent: 'center',
        alignItems: 'center',}}>
          <Text style={{
          fontSize: 20,
          color: '#FFFFFF',
          }}> 
          Login </Text>
        </View>
        </TouchableOpacity>

     </View>
        );
      }
/* Checking if the auth token is not empty directly sending the user to Home screen */
      else{
        return(
          <Home />
        );
    }
}
}

根据教程中的说明，Home.js为空白。