javascript - 从回调函数内部发送一个值来表达路由器

Question

当我从 POST 中保存新作者时，我想返回一条消息，说明新作者已保存。 (如果作者已经存在，我最终也会想要返回一些东西)我遇到的问题是，尽管作者保存在数据库中，但我无法写入 res.locals.messages 来自 author.save() 的回调参数。 (另外，请注意 createAuthor 是一组调用 - 我不确定这是否会使获取 result 的值变得更加困难。)

如何将 result 的值传递给路由器？

路线:

router.post('/', authorController.createAuthor, (req, res) => {
    res.json({ messages: res.locals.messages})
})

Controller :

exports.createAuthor = [

check('firstName', 'First name must be specified').isLength({min: 1}).trim(),
check('lastName', 'Last name must be specified').isLength({min: 1}).trim(),
sanitizeBody('firstName').trim().escape(),
sanitizeBody('lastName').trim().escape(),


(req, res, next) => {

    const errors = validationResult(req);
    var author = new Author({
        firstName: req.query.firstName,
        lastName: req.query.lastName
    });

    if (errors.isEmpty()) {

       //Edit: added find before save function:
        const query = {$or:[{firstName:{$regex: req.query.firstName, $options: 'i'}},
                {lastName:{$regex: req.query.lastName, $options: 'i'}}]} //TODO this regex fails if a parameter is missing.

        Author.findOne(query).sort([['lastName', 'ascending']]).exec((err, author) => {
            if (err) {
                return next(err)
            }

            if(!(author ==null)){
                var result = {status: "Author already exists: ", author_id: String(author.id)}
                res.locals.messages = result;
                next();
            }

        });


        author.save(function (err, newAuthor) {
            if (err) {
                return next(err)
            }

            var result = {status: "New author saved", author_id: String(newAuthor.id)}
            res.locals.messages = result;

        });
    }
    next();

}
];

Answer 1

在处理保存并设置 res.locals 值后，您需要调用 next :

exports.createAuthor = [

check('firstName', 'First name must be specified').isLength({min: 1}).trim(),
check('lastName', 'Last name must be specified').isLength({min: 1}).trim(),
sanitizeBody('firstName').trim().escape(),
sanitizeBody('lastName').trim().escape(),


(req, res, next) => {

    const errors = validationResult(req);
    var author = new Author({
        firstName: req.query.firstName,
        lastName: req.query.lastName
    });

    if (errors.isEmpty()) {
        author.save(function (err, newAuthor) {
            if (err) {
                return next(err)
            }

            var result = {status: "New author saved", author_id: String(newAuthor.id)}
            res.locals.messages = result;
            next();


        });
    } else {
        // Remember to do something about these non-empty errors!
        next(new Error('Got more than 0 errors'));
    }

}
];

此外，不要忘记处理验证错误数量非零的情况:)