使用Postman时如何解决nodejs中的CORS错误？

Question

我使用 nodejs 和 mongodb 创建了一个 REST Api，我想在 postman 中测试它，但在这样做时我收到了 CORS 错误。

var express = require('express');
var log = require('morgan')('dev');
var bodyParser = require('body-parser');

var properties = require('./config/properties');
var db = require('./config/database.js');
//hero routes
var herosRoutes = require('./api/heros/heros.routes');
var app = express();

//configure bodyparser
var bodyParserJSON = bodyParser.json();
var bodyParserURLEncoded = bodyParser.urlencoded({extended:true});

//initialise express router
var router = express.Router();

// call the database connectivity function
db.mongoc();

// configure app.use()
app.use(log);
app.use(bodyParserJSON);
app.use(bodyParserURLEncoded);

// Error handling
app.use(function(req, res, next) {
    res.setHeader("Access-Control-Allow-Origin", "*");
     res.setHeader("Access-Control-Allow-Credentials", "true");
     res.setHeader("Access-Control-Allow-Methods", "GET,HEAD,OPTIONS,POST,PUT");
     res.setHeader("Access-Control-Allow-Headers", "Access-Control-Allow-Origin,Access-Control-Allow-Headers, Origin,Accept, X-Requested-With, Content-Type, Access-Control-Request-Method, Access-Control-Request-Headers,Authorization");
   next();
 });

// use express router
app.use('/api',router);
//call heros routing
herosRoutes.hero(router);

// intialise server
app.listen(properties.PORT, (req, res) => {
    console.log(`Server is running on ${properties.PORT} port.`);
})

每当我发出任何创建或获取请求时，我都会在邮递员中收到此 CORS 错误。怎么解决这个问题呢？

CORS 错误：由于 CORS 策略，请求已被阻止

Answer 1

如果有人仍然遇到这个问题，Postman 在调用 API 时不会提供来源，因此当我们限制 CORS 策略时，会生成一个错误，提示Error: Not allowed by CORS。

绕过此问题的示例代码如下：

const whitelist = ['https://localhost:3001']
const corsOptions = {
 origin: function (origin, callback) {
    if(!origin){//for bypassing postman req with  no origin
      return callback(null, true);
    }
    if (whitelist.indexOf(origin) !== -1) {
      callback(null, true);
    } else {
      callback(new Error('Not allowed by CORS'))
    }
  }
}
app.use(cors(corsOptions));