Styjun

hey I want to make sure if I use the correct way for middleware in my simple express app, I am trying to find the email unique for register
here is my example

const isUnique = (req, res, next) => 
 User.findOne(
 where:
 email: req.body.email
 
 )
 .then(getUser => 
 if(getUser)
 next("/userAlreadyExist") // router
 // or can i render to to html? i am using ejs
 else 
 next()
 
 )
 .catch(next())



app.post('/register', isUnique ,(req, res) => 
 res.send(`thank you for register`)

I want to make sure the email already exists or no, so I want to pass it on middleware first, and get a page for isUnique, if the email already in use, I want to redirect it to next router called '/emailExist', and if it success i want to redirect it to router /success
can anyone help me if that code wrong or no? just want to make sure :D

You have a lot of options, here are a couple.

1. You can redirect users to specific pages based on whether or not the email exists. Within your /emailAlreadyExists and /registerSuccess routes you can render whatever templates you want or return some data.

const isUnique = (req, res, next) => 
 User.findOne(
 where:
 email: req.body.email
 
 )
 .then(getUser => 
 if (getUser) 
 res.redirect('/emailAlreadyExists');
 else 
 res.redirect('/registerSuccess'); // or just call next()
 
 )
 .catch(next("DB error"));

1. Pass along the results of the db query and let your final middleware handle it:

const isUnique = (req, res, next) => 
 User.findOne(
 where:
 email: req.body.email
 
 )
 .then(getUser => 
 req.user = getUser;
 next();
 )
 .catch(next());


app.post('/register', isUnique ,(req, res) => 
 if (req.user) 
 res.send('User already exists');
 else 
 res.send(`thank you for register`);
 

2. You can also create an error handling middleware:

const isUnique = (req, res, next) => 
 User.findOne(
 where:
 email: req.body.email
 
 )
 .then(getUser => 
 if(getUser)
 next("Error: user already exists"); // or some other error message/object
 else 
 next(); // continue to next middleware
 
 )
 .catch(next("DB error")); // handle errors throw from DB read



app.post('/register', isUnique ,(req, res) => 
 res.send(`thank you for register`)


/*
 If you call "next" with an argument, Express will skip 
 straight to this error handler route with the argument 
 passed as the "err" parameter
*/

app.use((err, req, res, next) => 
 console.error(err.stack);
 res.status(500).send(`An error occurred: $err`);
)