为什么连接users这个文档连接了两次，最后返回错误信息

Question

.post(,(req,res){
    = req..,
        = req..,
        = req.[],
        = req..;
    .();
    (!=){
        .();
        req.(,);
        res.()}
    = .(),
        = .(req..).();
    = ({
        :,
        :,
        :});
    .(.,(err,user){
        .();
        (err){
            .();
            req.(,err);
            res.();
        }
        (user){
            .();
            req.(,);
            res.();}

        .((err,user){
            .();
           (err){
               req.(,err);
               res.();}
            req..= ;.(req..);
            req.(,);
            .();
            res.();});
    });
});

.= (username,callback){
    .();
    .(username);
  .((err,db){
        .();
        (err){
            .();
            callback(err);}
        db.(,(err,collection){
            .();
            (err){
                .();
                .();
                callback(err);}
            .();
            collection.fineOne({: username,},(err,user){
                .();
                .();
                (err){
                    callback(err);}
                .();
                callback(,user);});
        });
    });
};

Answer 1

你这代码没发看呀