[英]Error in nodejs : Cannot set headers after they are sent to the client
我正在使用HTML和nodejs創建一個簡單的表單。 該表格接收電子郵件和密碼這兩個數據，並根據代碼中編寫的功能運行。
我的程序中有兩個文件app.js和index.html 。
app.js
const _ = require('lodash');
const express = require('express');
const path = require('path');
const Joi = require('joi');
const bodyParser = require('body-parser');
const app = express();
app.use(bodyParser.urlencoded({extended:false}));
app.use(bodyParser.json());
app.get('/',(req,res)=>{
res.sendFile(path.join(__dirname,'index.html'));
});
app.get('/example',(req,res)=>{
res.send('Hitting Example Route');
});
app.get('/example/:name/:age',(req,res)=>{
console.log(req.params);
console.log(req.query);
//res.send('example with route params');
res.send(req.params.name+":"+req.params.age);
});
app.post('/',(req,res)=> {
console.log(req.body);
const schema = Joi.object().keys({
email : Joi.string().trim().email().required(),
password : Joi.string().min(5).max(10).required()
});
Joi.validate(req.body,schema,(err,result)=>{
if(err)
{
console.log(err);
res.send('An error has occured');
}
console.log(result);
res.send('Successfully posted data');
});
//database work here
//res.json({success:true});
});
app.listen(3000);
index.html
<!DOCTYPE html>
<html>
<head>
<title>Text Input Control</title>
</head>
<body>
<!--<form !action="/"></form> method="POST" id="form">-->
<form method="POST" id="form">
First name: <input type = "text" name = "first_name" />
<br>
Last name: <input type = "text" name = "last_name" />
<input type="submit" value="Submit">
</form>
<script
src="http://code.jquery.com/jquery-3.3.1.js"
integrity="sha256-2Kok7MbOyxpgUVvAk/HJ2jigOSYS2auK4Pfzbm7uH60="
crossorigin="anonymous"></script>
<script>
$(document).ready(()=>{
$('#form').submit((e)=>{
e.preventDefault({});
$.ajax({
url : '/',
type : 'post',
contentType : 'application/json',
data : JSON.stringify($('#form').serializeArray()),
success : (response)=>{
console.log('Successfuly got response');
console.log(response);
}
});
});
});
</script>
</body>
</html>
我收到一條錯誤消息，指出Cannot set headers after they are sent to the client 。 我該如何修復代碼？
錯誤：
PS F:\DatabaseProject8> node app.js
[ { name: 'first_name', value: 'hello@gmail.com' },
{ name: 'last_name', value: 'gredyjht' } ]
{ ValidationError: "value" must be an object
at Object.exports.process (F:\DatabaseProject8\node_modules\joi\lib\errors.js:203:19)
at internals.Object._validateWithOptions (F:\DatabaseProject8\node_modules\joi\lib\types\any\index.js:764:31)
at module.exports.internals.Any.root.validate (F:\DatabaseProject8\node_modules\joi\lib\index.js:147:23)
at app.post (F:\DatabaseProject8\app.js:40:9)
at Layer.handle [as handle_request] (F:\DatabaseProject8\node_modules\express\lib\router\layer.js:95:5)
at next (F:\DatabaseProject8\node_modules\express\lib\router\route.js:137:13)
at Route.dispatch (F:\DatabaseProject8\node_modules\express\lib\router\route.js:112:3)
at Layer.handle [as handle_request] (F:\DatabaseProject8\node_modules\express\lib\router\layer.js:95:5)
at F:\DatabaseProject8\node_modules\express\lib\router\index.js:281:22
at Function.process_params (F:\DatabaseProject8\node_modules\express\lib\router\index.js:335:12)
isJoi: true,
name: 'ValidationError',
details:
[ { message: '"value" must be an object',
path: [],
type: 'object.base',
context: [Object] } ],
_object:
[ { name: 'first_name', value: 'hello@gmail.com' },
{ name: 'last_name', value: 'gredyjht' } ],
annotate: [Function] }
[ { name: 'first_name', value: 'hello@gmail.com' },
{ name: 'last_name', value: 'gredyjht' } ]
Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
at ServerResponse.setHeader (_http_outgoing.js:470:11)
at ServerResponse.header (F:\DatabaseProject8\node_modules\express\lib\response.js:767:10)
at ServerResponse.send (F:\DatabaseProject8\node_modules\express\lib\response.js:170:12)
at Joi.validate (F:\DatabaseProject8\app.js:47:13)
at internals.Object._validateWithOptions (F:\DatabaseProject8\node_modules\joi\lib\types\any\index.js:767:20)
at module.exports.internals.Any.root.validate (F:\DatabaseProject8\node_modules\joi\lib\index.js:147:23)
at app.post (F:\DatabaseProject8\app.js:40:9)
at Layer.handle [as handle_request] (F:\DatabaseProject8\node_modules\express\lib\router\layer.js:95:5)
at next (F:\DatabaseProject8\node_modules\express\lib\router\route.js:137:13)
at Route.dispatch (F:\DatabaseProject8\node_modules\express\lib\router\route.js:112:3)
您收到有關兩次設置標題的錯誤的原因是， Joi.validate回調中發生錯誤。 您正在發送“發生了錯誤”，但是在錯誤處理程序之后，您仍在發送“成功發布數據”。 您不應調用send兩次，否則會收到該錯誤。 發生錯誤時，您應該退出Joi.validate回調。
您定義的架構可能不正確
這樣定義
const schema = {
email: Joi.string().trim().email().required(),
password: Joi.string().min(5).max(10).required()
};
有時我遇到了這個問題，我為res.redirect('/example')解決了res.redirect('/example') res.send 。
您可以嘗試的另一件事是更改if語句，是否有可能在res.send執行兩次時出錯：
if(err){
console.log(err);
res.send('An error has occured');
}
else {
console.log(result);
res.send('Successfully posted data');
}
您收到的錯誤是由於Nodejs的異步特性。 使用Promise / Async-Await來防止此類錯誤。 使用異步等待
app.post('/',async(req,res)=> {
console.log(req.body);
const schema = Joi.object().keys({
email : Joi.string().trim().email().required(),
password : Joi.string().min(5).max(10).required()
});
let result = await Joi.validate(req.body,schema);
if(result.err){
console.log(err);
res.send('An error has occured');
}else{
console.log(result);
res.send('Successfully posted data');
}
//database work here
//res.json({success:true});
}）;
這可能會做
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[英]Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client in my nodeJS app
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