对预检请求的响应没有通过访问控制检查：没有'Access-Control-Allow-Origin'标头存在于角度js

Question

我已经使用nga admin使用节点js我是新的角度js和节点js。我已经在本地主机上使用mysql节点js创建了rest api，并且我使用邮递员检查了它，并且它的工作正常。但是，当我解析这个API网址时，它给了我下面的错误。看到我想创建管理面板让用户编辑删除和更新只需要实现基本的东西。但它的'显示我404错误HEADERS ERROR。

XMLHttpRequest无法加载http://localhost:3000/api/user?_page=1&_perPage=30&_sortDir=DESC&_sortField=id。对预检请求的响应不会通过访问控制检查：请求的资源上不存在“访问控制 - 允许来源”标头。因此不允许访问原产地'http://localhost'。 Server.js文件包含以下代码。

server.js文件

var express = require('express'), 
path  = require('path'), 
bodyParser = require('body-parser'), 
app = express(), 
expressValidator = require('express-validator'); 

app.use(bodyParser.urlencoded({ extended: true })); 
app.use(bodyParser.json({ type: 'application/vnd.api+json' })); 
app.use(bodyParser.json()); 
var connection = require('express-myconnection'), 
mysql = require('mysql'); 


app.use(

connection(mysql,{ 
    host  : 'localhost', 
    user  : 'root', 
    password : '', 
    database : 'gkv', 
    debug : true //set true if you wanna see debug logger 
},'request') 

); 

app.get('/',function(req,res){ 
res.send('Welcome'); 
}); 

var router = express.Router(); 

router.use(function(req, res, next) { 
console.log(req.method, req.url); 
console.log(res.headers); 
next(); 
}); 

var curut = router.route('/user'); 

curut.get(function(req,res,next){ 
res.header("Access-Control-Allow-Headers","Content-Type"); 
res.header("Access-Control-Allow-Origin", "*"); 
res.header("Access-Control-Allow-Methods", "GET, PUT, POST,OPTIONS"); 

req.getConnection(function(err,conn){ 

    if (err) return next("Cannot Connect"); 

    var query = conn.query('SELECT * FROM users',function(err,rows){ 

     if(err){ 
      console.log(err); 
      return next("Mysql error, check your query"); 
     } 
    res.json({message: 'All users!',data: rows }); 
     //res.render('user',{title:"RESTful Crud Example",data:rows}); 

    }); 

    }); 

    }); 


app.use('/api', router); 
    var server = app.listen(3000,function(){ 

     console.log("Listening to port %s",server.address().port); 

}); 

admin.js文件

var myApp = angular.module('myApp', ['ng-admin']); 
myApp.config(function($httpProvider) { 
//Enable cross domain calls 
$httpProvider.defaults.useXDomain = true; 

//Remove the header containing XMLHttpRequest used to identify ajax call 
//that would prevent CORS from working 

delete $httpProvider.defaults.headers.common['X-Requested-With']; 
$httpProvider.defaults.headers.common["Access-Control-Allow-Origin"] = "*"; 
$httpProvider.defaults.headers.common["Accept"] = "application/json"; 
$httpProvider.defaults.headers.common["content-type"] = "application/json"; 
}); 

myApp.config(['NgAdminConfigurationProvider', function (nga) { 


// create an admin application 
var admin = nga.application('My First Admin') 
    .baseApiUrl('http://localhost:3000/api/'); // main API endpoint 
// create a user entity 
// the API endpoint for this entity will be  'http://jsonplaceholder.typicode.com/users/:id 
var user = nga.entity('user'); 
// set the fields of the user entity list view 
user.listView().fields([ 
    nga.field('Nachname').isDetailLink(true), 
    nga.field('Anrede'), 
    nga.field('Emailadresse'), 
    nga.field('Telefonummer'), 
    nga.field('Date&Time'), 
    nga.field('URL'), 
    nga.field('UserIP'), 
]); 
user.creationView().fields([ 
nga.field('Nachname'), 
nga.field('Anrede'), 
nga.field('Emailadresse'), 
nga.field('Telefonummer'), 
nga.field('Date'), 
nga.field('URL'), 
nga.field('UserIP') 

]); 
//user.editionView().fields(user.creationView().fields()); 
admin.addEntity(user); 
/*var post=nga.entity('posts'); 
post.listView().fields([ 
nga.field('id'), 
nga.field('title'), 
nga.field('userId','reference').targetEntity(user).targetField(nga.field('username')).label('User'), 
nga.field('comments','referenced_list').targetEntity(nga.entity('comments')).targetReferenceField('postId').targetFields([nga.field('email'),nga.field('name')]).sortField('id').sortDir('DESC') 
]);*/ 
// add the user entity to the admin application 

//admin.addEntity(post); 
// attach the admin application to the DOM and execute it 
nga.configure(admin); 
}]); 

Answer 1

作为

我已经使用芯包NPM和使用节点JS CMD安装它和下面的代码添加这以上查询已经解决在server.js文件

cors = require('cors'); 
// use it before all route definitions 
app.use(cors({origin: 'http://localhost'})); 

Answer 2

我解决我的问题，通过添加以下到我的“app.js”文件，就像一个通道臂。

var app = express() 
, cors = require('cors') 
, app = express(); 
app.use(cors());