發送後無法設置標題。雖然調用create（data，cb）

Question

我是新來的節點，並試圖在mongodb中創建模型。當我打電話localhost：3000/a。我看到的請求兩次在控制檯也越來越誤差不能設置頭髮送之後

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 = "admin@test.com"; 
 
    User.create(user,cb); 
 
    res.send("hey"); 
 
    }); 
 
};

輸出：

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

當您完成您的請求發生錯誤和然後稍後嘗試發送更多相同的請求。這通常發生在有人在異步處理中犯了錯誤，這會在請求對象上發送事件的時間。

我看到你的代碼有兩個問題。首先，您嘗試從路由處理程序調用next()，就好像您還沒有真正完成處理請求一樣。其次，在您撥打next()之前，您發送的是res.send()，因爲User.create()是異步的，並且稍後會結束。

我建議你使用這個：

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 = "admin@test.com"; 
    User.create(user,function() { 
     res.send("hey"); 
    }); 
    });