Question

我正在尝试为我的react-native应用程序创建登录屏幕，但是当我尝试登录时，出现错误消息“ JSON解析错误：显示了意外的标记“ var””。

我在本地主机访问的另一个文件夹中有一个React Native应用程序和一个服务器应用程序。

我尝试更改var以查看会发生什么，但是随后我将得到相同的错误，但用let代替。

这是我的本机代码

    login = () => {
        fetch('http://192.168.0.105:8888/loginbackend/routes/users.js', {
            method: 'POST',
            header: {
                'Content-Type': 'application/json',
                'Accept': 'application/json',
            },
            body: JSON.stringify({
                username: this.state.username,
                password: this.state.password,
            })
        })

            .then((response) => response.json())
            .then ((res) => {

                if (res.success === true) {
                    AsyncStorage.setItem('user', res.user);
                    this.props.navigation.navigate('Profile');
                }
                else {
                    alert(res.message);
                }
            })
            .done();
    }
}

我的服务器文件

var express = require('express');
var router = express.Router();
var mysql = require('mysql');

var connection = mysql.createConnection({
  host: 'localhost',
  user: 'root',
  password: 'root',
  database: 'users'
});

router.POST('/', function(req, res) {

  var username = req.body.username;
  var password = req.body.password;

  connection.query(
    "SELECT * FROM user WHERE username = ? AND password = ?",
    [username, password], function (err, row){

      if (err) {
        console.log(err);
        res.send({ 'success': false, 'message': 'Kan niet met de database verbinden'});
      }

      if (row.length > 0 ){
        res.send({ 'success': true, 'user': row[0].username });
      } else {
        res.send({ 'success': false, 'message': 'Gebruiker niet gevonden'});
      }
    });
});

module.exports = router;

之前，我遇到了JSON Parse错误：意外令牌'<'，但是现在它的JSON Parse错误：意外标识符“ var”。如果凭据不正确，我将无法登录，也不会收到警报。

Answer 1

Express设置不正确，在我的应用程序文件中，我已将“ header”更改为“ headers”。

应用文件

login = () => {
        fetch('http://localhost:8080/users/', {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json',
                'Accept': 'application/json',
            },
            body: JSON.stringify({
                "username": this.state.username,
                "password": this.state.password,
            })
        })

            .then((response) => response.json())
            .then ((res) => {

                if (res.success === true) {
                    AsyncStorage.setItem('user', res.user);
                    this.props.navigation.navigate('Profile');
                }
                else {
                    alert(res.message);
                }
            })
            .done();
    }
}

表达文件App.js

const port = 8080;

var createError = require('http-errors');
var express = require('express');
var path = require('path');
var cookieParser = require('cookie-parser');
var logger = require('morgan');
var bodyParser = require('body-parser');
var mysql = require('mysql');

var indexRouter = require('./routes/index');
var usersRouter = require('./routes/users');

var app = express();

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');

app.use(logger('dev'));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

app.use('/', indexRouter);
app.use('/users', usersRouter);

// catch 404 and forward to error handler
app.use(function(req, res, next) {
  next(createError(404));
});

// error handler
app.use(function(err, req, res, next) {
  // set locals, only providing error in development
  res.locals.message = err.message;
  res.locals.error = req.app.get('env') === 'development' ? err : {};

  // render the error page
  res.status(err.status || 500);
  res.render('error');
});

app.listen(port, () => console.log(`Backend now listening on ${port}!`));

module.exports = app;

表达users.js

var express = require('express');
var router = express.Router();
var mysql = require('mysql');

var connection = mysql.createConnection({
  host: '127.0.0.1',
  user: 'root',
  password: 'root',
  database: 'users',
  port: 8889
});

router.post('/', function(req, res) {

  var username = req.body.username;
  var password = req.body.password;


  connection.query(
    "SELECT * FROM user WHERE username = ? AND password = ?",
    [username, password], function (err, row){

      if (err) {
        console.log(err);
        res.send({ 'success': false, 'message': 'Kan niet met de database verbinden'});
      }

      if (row.length > 0 ){
        res.send({ 'success': true, 'user': row[0].username });
      } else {
        res.send({ 'success': false, 'message': 'Gebruiker niet gevonden'});
      }
    });
});

module.exports = router;

希望这对卡在同一事物上的人有所帮助。

React-Native JSON Parse错误：意外的标识符“ var”

1 个答案: