javascript - Node : Code optimization and variable scoping

Question

纯 Javascript 编程的新手，我只是想知道如何优化下面的冗余代码:

module.exports = function(app, express) {
    var router = express.Router();

    router.get('/', function (req, res, next) {
        var db = req.db;
        var collection = db.get('projects');
        var projects = collection.find({}, {}, function(e, docs){
            res.json({
                success: true,
                message : 'ok',
                projects: docs
            });
        });
    });

    router.get('/:id', function (req, res, next) {
        var db = req.db;
        var collection = db.get('projects');
        var projects = collection.find({_id: req.params.id}, {}, function(e, docs){
            res.json({
                success: true,
                message : 'ok',
                project: docs
            });
        });
    });

    return router;
};

如您所见，从 var db 开始到 res.json() block 的代码都是可优化的，但我不确定如何继续处理它。有什么想法吗，伙计们？

谢谢!

Answer 1

您可以编写一个函数来将查询结果返回给客户端:

function handleQuery(query, req, res, next) {
    var db = req.db;
    var collection = db.get('projects');
    var projects = collection.find(query, {}, function(e, docs){
        res.json({
            success: true,
            message : 'ok',
            project: docs
        });
    });
}

然后你的路线可以折叠成这些:

router.get('/', function (req, res, next) {
    handleQuery({}, req, res, next);
});

router.get('/:id', function (req, res, next) {
    handleQuery({_id: req.params.id}, req, res, next);
});

当您这样做时，请意识到您没有正确处理错误。要正确处理错误，您应该检查 e 的值。如果它是真实的，你有一个错误，你需要适本地处理它，例如像这样:

function handleQuery(query, req, res, next) {
    var db = req.db;
    var collection = db.get('projects');
    var projects = collection.find(query, {}, function(e, docs){
        if(e) {
            return next(e);
        }
        res.json({
            success: true,
            message : 'ok',
            project: docs
        });
    });
}