How to handle the sequelize unique constraint error?

Admin 1
Viewed 7465

I am new to javascript and I need to handle constraint error in sequelize. I searched related to this topic everywhere, but still, I couldn't get a proper workable answer. My attempt it as follows.

app.post('/api/users', (req, res) => {
  try {
    console.log(req.body);
    User.create(req.body)
        .then(user=> res.json(user));
  } catch (error) {
    console.log("Error: "+error);
  }});

Here couldn't catch the exception yet. For a valid user input it is able to post the request. So I just need to know a way to handle the exception.

sequelize.js node.js
3 Answers

Was looking around for an answer for this, but was not really satisfied with the two given. If you are looking to return a correct response such as a 403 this is the solution I have came up with.

app.post('/api/users', async (req, res) => {
    try {
        console.log(req.body);
        var user = await User.create(req.body)
        return res.status(200).json({ status: 'success', result: res.json(user) })
    } catch (error) {
        if (error.name === 'SequelizeUniqueConstraintError') {
            res.status(403)
            res.send({ status: 'error', message: "User already exists"});
        } else {
            res.status(500)
            res.send({ status: 'error', message: "Something went wrong"});
        }
    }
});
user_53909070

You can use Promise with .then().catch(), or use async/await with try/catch

This is Promise

app.post('/api/users', (req, res) => {
    console.log(req.body);
    User.create(req.body)
        .then(user=> res.json(user))
        .catch(err => console.log(err))
});

This is async/await

app.post('/api/users', async (req, res) => {
    try {
      console.log(req.body);
      const user = await User.create(req.body);
      res.json(user);
    } catch (error) {
      console.log("Error: "+error);
    }
});
user_88284890

Looks like you're mixing two different styles. If you're using then(), then the try catch block is unnecessary:

app.post('/api/users', (req, res) => {
  console.log(req.body)
  User.create(req.body)
    .then(user => res.json(user))
    .catch(error => console.log('Error: ' + error))
})

The other style would be using the async package. With async, your code would look like this:

app.post('/api/users', async (req, res) => {
  console.log(req.body)
  try {
    const user = await User.create(req.body)
    res.json(user)
  }
  catch (error) { console.log('Error: ' + error) }
})

Both methods have their advantages and disadvantages that go beyond this snippet and lot of people use both as appropriate, for example the await approach works only inside a function declared with async like in the second example :async (req, res). In such cases, using then() style promise handling is a better approach

user_8310310
Related