在 NodeJs 和 Express 中更好的错误处理代码

Question

I have this code for a post request, when the user wants to change his password. Because of all the cases and the following page renders the code came out really ugly. Is there a better way to structure this? (It works fine and does what I want.)

// Check if old password is correct
    SQL.getUserFromDB(request.session.username).then(function (results) {
        // Hash and compare with stored hash
        bcrypt.compare(request.body.oldPw, results[0].password, function (error, result) {
            // Log possible error
            if (error) console.log(error);
            if (result === true) {
                // Check if new passwords are both the same
                if (request.body.newPw === request.body.newPw2) {
                    // Call mysql function
                    SQL.changeUserPassword(request.session.username, request.body.newPw).then(function () {
                        response.render('pages/changePassword', {
                            user: request.session.username,
                            text: 'Passwort erfolgreich geändert.'
                        });
                    }).catch(function (error) {
                        console.log(error);
                        if (error == 'pw') {
                            response.render('pages/changePassword', {
                                user: request.session.username,
                                text: 'Neues Passwort zu unsicher.'
                            });
                        } else {
                            // Render error page
                            response.render('pages/changePassword', {
                                user: request.session.username,
                                text: 'Fehler beim Ändern des Passworts.'
                            });
                        }
                    });
                } else {
                    // Render error page
                    response.render('pages/changePassword', {
                        user: request.session.username,
                        text: 'Neue Passwörter stimmen nicht überein!'
                    });
                }
            } else {
                // Render error page
                response.render('pages/changePassword', {
                    user: request.session.username,
                    text: 'Altes Passwort stimmt nicht überein!'
                });
            }
        });
        // Catch sql errorsFehler beim Ändern des Passworts
    }).catch(function (error) {
        if (error) console.log(error);
        response.render('pages/errors/loginFailed');
    });

I tried just setting the text in the different cases and rendering one page with the text at the bottom, this didn't work however.

Answer 1

You can write a function to render error operations and call it in different places. For error messages, create a config file and define them in a bug report and call and use wherever it was needed.

var configError = require('./config');

function renderErrorPage () {
   response.render('pages/changePassword', {
     user: request.session.username,
     text: configError[0]
   });
}

---

file/config.js

exports.x = [
   'Neue Passwörter stimmen nicht überein!',
   'Altes Passwort stimmt nicht überein!',
   'Neues Passwort zu unsicher.'
]

and render error page in else condition convert to :

else {
        // Render error page
       /*response.render('pages/changePassword', {
           user: request.session.username,
           text: 'Altes Passwort stimmt nicht überein!'
        });*/

        renderErrorPage();

   }