反应本机登录以获取user_id

Question

https://reactnativecode.com/react-native-user-login-using-php-mysql/ I am following the above link to do a simple login app hence I would like to get the user_id after I login but fail, can someone please show me how to do it to display user_id after login?

Below is the code for php

<?php 
// Importing DBConfig.php file.
include 'DBConfig.php';

// Creating connection.
 $con = mysqli_connect($HostName,$HostUser,$HostPass,$DatabaseName);

 // Getting the received JSON into $json variable.
 $json = file_get_contents('php://input');

 // decoding the received JSON and store into $obj variable.
 $obj = json_decode($json,true);

// Populate User email from JSON $obj array and store into $email.
$email = $obj['email'];

// Populate Password from JSON $obj array and store into $password.
$password = $obj['password'];

//Applying User Login query with email and password match.
$Sql_Query = "select * from user where email = '$email' and password = '$password' ";

// Executing SQL Query.
$check = mysqli_fetch_array(mysqli_query($con,$Sql_Query));


if(isset($check)){

 $SuccessLoginMsg = 'Data Matched';

 // Converting the message into JSON format.
$SuccessLoginJson = json_encode($SuccessLoginMsg);

// Echo the message.
 echo $SuccessLoginJson ; 

 }

 else{

 // If the record inserted successfully then show the message.
$InvalidMSG = 'Invalid Username or Password Please Try Again' ;

// Converting the message into JSON format.
$InvalidMSGJSon = json_encode($InvalidMSG);

// Echo the message.
 echo $InvalidMSGJSon ;

 }

 mysqli_close($con);
?>

And here is react native code which allow user login

import React, { Component } from 'react';

import { StyleSheet, TextInput, View, Alert, Button, Text} from 'react-native';

// Importing Stack Navigator library to add multiple activities.
import { StackNavigator } from 'react-navigation';

// Creating Login Activity.
class LoginActivity extends Component {

  // Setting up Login Activity title.
  static navigationOptions =
   {
      title: 'LoginActivity',
   };

constructor(props) {

    super(props)

    this.state = {

      UserEmail: '',
      UserPassword: ''

    }

  }

UserLoginFunction = () =>{

 const { UserEmail }  = this.state ;
 const { UserPassword }  = this.state ;


fetch('http://localhost/login/login.php', {
  method: 'POST',
  headers: {
    'Accept': 'application/json',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({

    email: UserEmail,

    password: UserPassword

  })

}).then((response) => response.json())
      .then((responseJson) => {

        // If server response message same as Data Matched
       if(responseJson === 'Data Matched')
        {

            //Then open Profile activity and send user email to profile activity.
            this.props.navigation.navigate('Second', { Email: UserEmail });

        }
        else{

          Alert.alert(responseJson);
        }

      }).catch((error) => {
        console.error(error);
      });


  }

  render() {
    return (

<View style={styles.MainContainer}>

        <Text style= {styles.TextComponentStyle}>User Login Form</Text>

        <TextInput

          // Adding hint in Text Input using Place holder.
          placeholder="Enter User Email"

          onChangeText={UserEmail => this.setState({UserEmail})}

          // Making the Under line Transparent.
          underlineColorAndroid='transparent'

          style={styles.TextInputStyleClass}
        />

        <TextInput

          // Adding hint in Text Input using Place holder.
          placeholder="Enter User Password"

          onChangeText={UserPassword => this.setState({UserPassword})}

          // Making the Under line Transparent.
          underlineColorAndroid='transparent'

          style={styles.TextInputStyleClass}

          secureTextEntry={true}
        />

        <Button title="Click Here To Login" onPress={this.UserLoginFunction} color="#2196F3" />



</View>

    );
  }
}

// Creating Profile activity.
class ProfileActivity extends Component
{

  // Setting up profile activity title.
   static navigationOptions =
   {
      title: 'ProfileActivity',

   };


   render()
   {

     const {goBack} = this.props.navigation;

      return(
         <View style = { styles.MainContainer }>

            <Text style = {styles.TextComponentStyle}> { this.props.navigation.state.params.Email } </Text>

            <Button title="Click here to Logout" onPress={ () => goBack(null) } />

         </View>
      );
   }
}

export default MainProject = StackNavigator(
{
   First: { screen: LoginActivity },

   Second: { screen: ProfileActivity }

});

const styles = StyleSheet.create({

MainContainer :{

justifyContent: 'center',
flex:1,
margin: 10,
},

TextInputStyleClass: {

textAlign: 'center',
marginBottom: 7,
height: 40,
borderWidth: 1,
// Set border Hex Color Code Here.
 borderColor: '#2196F3',

 // Set border Radius.
 borderRadius: 5 ,

},

 TextComponentStyle: {
   fontSize: 20,
  color: "#000",
  textAlign: 'center',
  marginBottom: 15
 }
});