我已经使用Node/Express创建了一个小API，并试图使用Angularjs拉数据，但由于我的html页面在localhost:8888和节点API在端口3000上监听下运行，我得到了No 'Access-Control-Allow-Origin'。我尝试使用node-http-proxy和Vhosts Apache，但没有太多成功，请参阅下面的完整错误和代码。
XMLHttpRequest无法加载localhost:3000。被请求的资源上没有'Access-Control-Allow-Origin'标头。因此，不允许访问Origin 'localhost:8888'。”
// Api Using Node/Express
var express = require('express');
var app = express();
var contractors = [
{
"id": "1",
"name": "Joe Blogg",
"Weeks": 3,
"Photo": "1.png"
}
];
app.use(express.bodyParser());
app.get('/', function(req, res) {
res.json(contractors);
});
app.listen(process.env.PORT || 3000);
console.log('Server is running on Port 3000')
角码
angular.module('contractorsApp', [])
.controller('ContractorsCtrl', function($scope, $http,$routeParams) {
$http.get('localhost:3000').then(function(response) {
var data = response.data;
$scope.contractors = data;
})
HTML
<body ng-app="contractorsApp">
<div ng-controller="ContractorsCtrl">
<ul>
<li ng-repeat="person in contractors">{{person.name}}</li>
</ul>
</div>
</body>
尝试在你的NodeJS/Express应用程序中添加以下中间件(为了方便起见，我添加了一些注释):
// Add headers before the routes are defined
app.use(function (req, res, next) {
// Website you wish to allow to connect
res.setHeader('Access-Control-Allow-Origin', 'http://localhost:8888');
// Request methods you wish to allow
res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE');
// Request headers you wish to allow
res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type');
// Set to true if you need the website to include cookies in the requests sent
// to the API (e.g. in case you use sessions)
res.setHeader('Access-Control-Allow-Credentials', true);
// Pass to next layer of middleware
next();
});
(您可能需要使用127.0.0.1而不是localhost。)
除了所有列出的答案外，我还犯了同样的错误
我可以访问前端和后端，我已经添加了cors模块app.use(cors());尽管如此，我还是在为这个错误而挣扎。
经过一些调试后，我发现了这个问题。当我上传一个大小超过1mb的媒体时，Nginx服务器抛出了错误
<html>
<head>
<title>413 Request Entity Too Large</title>
</head>
<body>
<center>
<h1>413 Request Entity Too Large</h1>
</center>
<hr>
<center>nginx/1.18.0</center>
</body>
</html>
但是在前台控制台，我发现了这个错误
Access to XMLHttpRequest at 'https://api.yourbackend.com' from origin 'https://web.yourfromntend.com' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.
这让人很困惑。但是这个错误的路由原因来自nginx配置。这只是因为指令client_max_body_size的值默认设置为0。它决定了允许的HTTP请求大小是client_max_body_size。这个指令可能已经在你的nginx.conf文件(位于/etc/nginx/nginx.conf)中定义了。现在你需要在http或服务器上添加/编辑client_max_body_size指令的值。
server {
client_max_body_size 100M;
...
}
一旦你设置了你想要的值，保存你的更改并重新加载Nginx: service Nginx reload
经过这些改变，它运行得很好
参考:https://www.keycdn.com/support/413-request-entity-too-large: ~:文本= % 23日处理% 20 % 20 % 20的web服务器% 20。= % 20例% 20请求% 2 c % 20 % 5月20日,如% 20 % 20大% 20媒体% 20文件)。
尝试在你的NodeJS/Express应用程序中添加以下中间件(为了方便起见，我添加了一些注释):
// Add headers before the routes are defined
app.use(function (req, res, next) {
// Website you wish to allow to connect
res.setHeader('Access-Control-Allow-Origin', 'http://localhost:8888');
// Request methods you wish to allow
res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE');
// Request headers you wish to allow
res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type');
// Set to true if you need the website to include cookies in the requests sent
// to the API (e.g. in case you use sessions)
res.setHeader('Access-Control-Allow-Credentials', true);
// Pass to next layer of middleware
next();
});
(您可能需要使用127.0.0.1而不是localhost。)
另一种方法是简单地添加头到你的路由:
router.get('/', function(req, res) {
res.setHeader('Access-Control-Allow-Origin', '*');
res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE'); // If needed
res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type'); // If needed
res.setHeader('Access-Control-Allow-Credentials', true); // If needed
res.send('cors problem fixed:)');
});
