Node.js（Express）错误处理中间件与路由器 [英] Node.js (Express) error handling middleware with router

问题描述

这是我的申请结构：

- app.js
- routes
---- index.js

ExpressJS 应用创建错误开发和生产环境的处理程序。这是来自 app.js的代码片段：

The ExpressJS app creates error handlers for development and production environments. Here's a code snippet from app.js:

app.use('/', routes); // routing is handled by index.js in the routes folder

//The following middleware are generated when you create the Express App

// catch 404 and forward to error handler
app.use(function (req, res, next) {
    var err = new Error('Not Found');
    err.status = 404;
    next(err);
});

// development error handler
// will print stacktrace
if (app.get('env') === 'development') {
    app.use(function (err, req, res, next) {
        res.status(err.status || 500);
        res.render('error.ejs', {
            message: err.message,
            error: err
        });
    });
}

// production error handler
// no stacktraces leaked to user
app.use(function (err, req, res, next) {
    res.status(err.status || 500);
    res.render('error', {
        message: err.message,
        error: {}
    });
});

在 routes / index.js 内，我处理所有路由：

And inside of routes/index.js, where I handle all the routing:

var router = express.Router();

router.get('/', function (req, res) {
    someAsyncFunction(function(err, result) {
        if (err) throw err; // Handle this error
    }
});

module.exports = router;

我希望将错误传递给其中一个错误处理程序而不是抛出。我该怎么做？

I want the err to be passed to one of the error handlers instead of being thrown. How can I do this?

推荐答案

你必须把它传递给下一个回调，它通常是路由处理程序中的第三个参数

You have to pass it to the next callback which is usually the third parameter in the route handler

var router = express.Router();

router.get('/', function (req, res, next) {
    someAsyncFunction(function(err, result) {
        if (err) {
            next(err); // Handle this error
        }
    }
});

module.exports = router;

调用 next （错误）将允许使用以下签名在链中的中间件中捕获错误：

calling next(err) will allow the error to be caught in a middleware down the chain with the following signature:

app.use(function (err, req, res, next){
    // do something about the err
});

参考： http://expressjs.com/en/guide/error-handling.html

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