对于某些页面，我的应用程序中有自定义的 500、404 和 403 错误处理。例如，在数据库查询失败后，我会去：
return next({status: 404, message: 'Record not found'});
或
return next(new Error('Bad things have happened')});
在我的中间件中，我有一个错误处理程序：
app.use(function (err, req, res, next) {
// handle error
});
问题是永远不会调用错误处理程序，而是将错误调用堆栈打印到浏览器中。我希望处理程序呈现自定义错误页面。
应用.js
var express = require('express')
, app = express()
, swig = require('swig')
, config = require('./lib/config')
, env = process.env.NODE_ENV || 'development'
, path = require('path');
config.configure(env);
app.engine('html', swig.renderFile);
app.set('view cache', false);
swig.setDefaults({
cache: config.get('swigCache')
});
app.set('view engine', 'html');
app.set('views', __dirname + '/lib/views');
require('./lib/util/swig');
require('./lib/initialisers/mongodb')();
require('./lib/initialisers/aws')();
require('./lib/middleware')(app); // first load middleware
require('./lib/routes')(app); // then routes
var server = app.listen(config.get('port'), function() {
console.info('config: ' + JSON.stringify(config.getCurrent()));
console.info('NODE_ENV: ' + env);
console.info('server running: ' + JSON.stringify(server.address()));
});
路线.js
module.exports = function(app){
app.get('/', require('./views/').index);
app.get('/blog', require('./views/blog').index);
app.get('/blog/:slug', require('./views/blog').getBySlug);
app.route('/report/:slug')
.get(require('./views/report/').index)
.post(require('./views/report/').doReport);
// Very long file with tons of routes. Simplified version.
中间件.js
var express = require('express')
, app = express()
, path = require('path')
, logger = require('morgan')
, cookieParser = require('cookie-parser')
, bodyParser = require('body-parser')
, passport = require('passport')
, session = require('express-session')
, mongoStore = require('connect-mongo')(session)
, compression = require('compression')
, favicon = require('serve-favicon')
, config = require('./config')
, flash = require('connect-flash')
, multer = require('multer')
, csrf = require('csurf');
module.exports = function(app) {
app.use(bodyParser.urlencoded({ extended: false }))
app.use(bodyParser.json());
app.use(cookieParser());
app.use(csrf({ cookie: true }));
app.use(express.static(path.join(__dirname, config.get('staticContentPath')), {
maxAge: (60 * 60 * 24) * 1000
}));
app.use(session({
resave: true,
saveUninitialized: true,
secret: 'da755fc0-6882-11e4-9803-0800200c9a66',
cookie: {
maxAge: 24 * 60 * 60 * 1000 // 24 hrs
},
store: new mongoStore({
url: config.getMongoConn()
})
}));
app.use(logger('dev'));
app.use(flash());
/**
* 301 redirects
*/
app.use(function(req, res, next) {
var host = req.get('host');
// AWS IP --> http
if (host == 'xx.xxx.xxx.xxx') {
return res.redirect(301, config.get('url') + req.originalUrl);
}
// AWS origin --> http
if(host == 'xxx-xxx-xxx-xxx-xxx.ap-southeast-2.compute.amazonaws.com'){
return res.redirect(301, config.get('url') + req.originalUrl);
}
// www --> http
if (/^www./.test(host)) {
host = host.substring(4, host.length);
return res.redirect(301, req.protocol + '://' + host + req.originalUrl);
}
// Trailing slash --> http
if (req.path.substr(-1) == '/' && req.path.length > 1) {
var query = req.url.slice(req.path.length);
return res.redirect(301, req.path.slice(0, -1) + query);
}
next();
});
// Delete expired Mongo sessions from DB
app.use(function (req, res, next) {
req.session._garbage = new Date();
req.session.touch();
next();
});
/**
* Setting Cache control header for Ajax requests to 30 minutes
*/
app.use(function (req, res, next) {
if(req.xhr){
res.header('Cache-Control', 'max-age=' + 1800 + ', public');
}
next();
});
app.use(compression());
app.use(
multer({
dest: config.get('uploads').folders.temp
})
);
app.use(passport.initialize());
app.use(passport.session());
var initPassport = require('./passport/init');
initPassport(passport);
app.use(function (req, res, next) {
res.locals = {
root : 'http://' + req.headers.host,
sitename : require('./config').get('sitename'),
config: config.get('env'),
url : config.get('url'),
user : req.user,
flash : req.flash()
};
next();
});
app.use(function (err, req, res, next) {
if (err.code !== 'EBADCSRFTOKEN'){
return next(err);
}
if(req.xhr){
return res.ok({payload: null}, '403 invalid csrf token');
}
// TODO handle CSRF token errors here
res.status(403);
res.send('form tampered with')
});
// This is never called when throwing errors like
// next(new Error('some error') or
// next({status: 500, message:'server error'});
app.use(function (err, req, res, next) {
console.error(err.stack);
// render an error page
});
};
问题是，错误处理程序应始终位于应用程序堆栈的末尾。这意味着，您可以将错误处理程序从中间件移动到应用.js并在需要后使用它们 （app.use（）），或者在中间件之前包含路由。
注意：您的错误处理程序中间件必须有 4 个参数：error、req、res、next。否则，处理程序不会触发。
我遇到了同样的问题，花一整天的时间解决问题。最后，找到了一个简单的解决方法。这对我非常有效。您需要将客户错误处理程序放在服务器实例文件 （App.js/server.js 的侦听器处理程序之前。 祝你好运:)
app.use((error, req, res, next) => {
if (res.headersSent) {
return next(err)
}
res.status(500).send('INTERNAL SERVER ERROR !')
});
app.listen(3000, function() {
console.log('Node app is running on port 3000');
});
module.exports = app;
为了处理在 Express 中异步执行代码期间引发的错误（版本 5.x<），您需要使用 next() 函数手动捕获并调用内置错误处理程序（或自定义处理程序）。
app.get('/', (req, res, next) => {
setTimeout(() => {
try {
console.log('Async code execution.')
throw new Error('Unexpected error on async!')
} catch (error) {
// manually catching and propagating to your error handler
next(error)
}
}, 100)
})
// as a last declaration in your entrypoint
app.use((err, req, res, next) => {
// do some error handling here. if you do not call next, you must return a response from here.
})
错误处理程序应始终位于应用程序堆栈的末尾。显然，这不仅意味着毕竟app.use()，而且意味着在您所有的app.get()和app.post()电话之后。
如果您不想为每个异步路由器处理程序编写三个参数以便能够全局捕获错误：
npm install express-async-errors
import 'express-async-errors';
app.get('/api/endpoint', async (req, res) => {
const user = await User.findByToken(req.get('authorization'));
if (!user) throw Error("access denied"); //will propagate to global error handler
});