带有Express的Node.js-抛出错误与下一个错误 [英] Node.js with Express - throw Error vs next(error)

问题描述

有人可以说明在node.js Express应用程序中合适的时间抛出诸如此类的错误吗?

Can someone expound on the times when it's appropriate in a node.js Express app to throw an error like so:

throw new Error('my error');

或通过通常标有"next"的回调传递此错误，如下所示:

or to pass this error on via the callback usually labelled 'next' like so:

next(error);

您能否解释一下在Express应用程序中它们各自将做什么?

and could you please explain what each of them will do in the context of an Express app?

例如，这是一个处理URL参数的快速函数:

for example, here is an express function dealing with URL parameters:

app.param('lineup_id', function (req, res, next, lineup_id) {
        // typically we might sanity check that user_id is of the right format
        if (lineup_id == null) {
            console.log('null lineup_id');
            req.lineup = null;
            return next(new Error("lineup_id is null"));
        }

        var user_id = app.getMainUser()._id;
        var Lineup = app.mongooseModels.LineupModel.getNewLineup(app.system_db(), user_id);
        Lineup.findById(lineup_id, function (err, lineup) {
            if (err) {
                return next(err);
            }
            if (!lineup) {
                console.log('no lineup matched');
                return next(new Error("no lineup matched"));
            }
            req.lineup = lineup;
            return next();
        });
    });

在注释行中"//我应该在这里创建自己的错误吗?" 我可以使用引发新的Error('xyz')"，但这究竟会做什么?为什么通常将错误传递给回调"next"更好?

In the line commented "//should I create my own error here?" I could used "throw new Error('xyz')", but what exactly would that do? Why is it usually better to pass the error to the callback 'next'?

另一个问题是-在开发过程中，如何在控制台以及浏览器中显示引发新错误('xyz')"?

Another question is - how do I get "throw new Error('xyz')" to show up in the console as well as the browser when I am in development?

推荐答案

一般来说，express遵循传递错误而不是抛出错误的方式，对于程序中的任何错误，您都可以将错误对象传递给'next'，需要定义错误处理程序，以便可以正确处理传递给next的所有错误

In general express follows the way of passing errors rather than throwing it, for any errors in the program you can pass the error object to 'next' , also an error handler need to be defined so that all the errors passed to next can be handled properly

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

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