发送后无法设置标题。虽然调用create（data，cb）

Question

我是新来的节点，并试图在mongodb中创建模型。当我打电话localhost：3000/a。我看到的请求两次在控制台也越来越误差不能设置头发送之后

module.exports = function(app) { 
 
    app.get('/',function(req,res){ 
 
    res.render("adminpanel/panel",{}); 
 
    }); 
 
    app.get('/a',function (req,res,cb) { 
 
    console.log(req.url) 
 
    var User = app.models.test; 
 
    var user = app.models.test(); 
 
    user.username = "admin"; 
 
    user.type = "hey"; 
 
    user.password = "132"; 
 
    user.email = "[email protected]"; 
 
    User.create(user,cb); 
 
    res.send("hey"); 
 
    }); 
 
};

输出：

output: 
 
    /a 
 
    /a 
 
    Error: Can't set headers after they are sent. 
 
    at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:344:11) 
 
    at ServerResponse.header (E:\workspace\orderapp\node_modules\express  \lib\response.js:718:10) 
 
    at ServerResponse.contentType (E:\workspace\orderapp\node_modules\express\lib\response.js:551:15) 
 
    at ServerResponse.send (E:\workspace\orderapp\node_modules\express\lib\response.js:138:14) 
 
    at E:\workspace\orderapp\server\boot\root.js:14:9 
 
    at Layer.handle [as handle_request] (E:\workspace\orderapp\node_modules\express\lib\router\layer.js:95:5) 
 
    at next (E:\workspace\orderapp\node_modules\express\lib\router\route.js:131:13) 
 
    at Route.dispatch (E:\workspace\orderapp\node_modules\express\lib\router\route.js:112:3) 
 
    at Layer.handle [as handle_request] (E:\workspace\orderapp\node_modules\express\lib\router\layer.js:95:5) 
 
    at E:\workspace\orderapp\node_modules\express\lib\router\index.js:277:22

Answer 1

当您完成您的请求发生错误和然后稍后尝试发送更多相同的请求。这通常发生在有人在异步处理中犯了错误，这会在请求对象上发送事件的时间。

我看到你的代码有两个问题。首先，您尝试从路由处理程序调用next()，就好像您还没有真正完成处理请求一样。其次，在您拨打next()之前，您发送的是res.send()，因为User.create()是异步的，并且稍后会结束。

我建议你使用这个：

app.get('/a',function (req,res) { 
    console.log(req.url) 
    var User = app.models.test; 
    var user = app.models.test(); 
    user.username = "admin"; 
    user.type = "hey"; 
    user.password = "132"; 
    user.email = "[email protected]"; 
    User.create(user,function() { 
     res.send("hey"); 
    }); 
    });