Node.js + Joi how to display a custom error messag

Question

It seems pretty straight forward to validate user's input in Node.js RESTapi with Joi.

But the problem is that my app is not written in English. That means I need to send a custom written messages to the frontend user.

I have googled for this and only found issues.

Maybe could someone give a solution for this?

This is the code I am using to validate with the Joi system:

    var schema = Joi.object().keys({
      firstName: Joi.string().min(5).max(10).required(),
      lastName: Joi.string().min(5).max(10).required()
      ..
    });

    Joi.validate(req.body, schema, function(err, value) {
      if (err) {
        return catched(err.details); 
      }
    });

    function catched(reject) {
      res.json({
        validData: false,
        errors: reject
      });
    }

Plus, is there a way to use Joi in client side?

Thanks!

Answer 1

Solution to add custom messages: Simply add another chained function to throw error while defining your schema.
In your case

 firstName: Joi.string().min(5).max(10).required().error(new Error('I am a custom error and I know it!')),

Rest will remain same.

Solution to use Joi at client side (Your 2nd question)

Joi-Browser is the package which enables usage of the same schema at the client side.

Here is an interesting discussion you can have a look at.

Cheers!

Answer 2

You can use .error(new Error('message')), And its work for me

var schema = Joi.object().keys({
  firstName: Joi.string().min(5).max(10).required().error(new Error('Give your error message here for first name')),
  lastName: Joi.string().min(5).max(10).required().error(new Error('Give your error message here for last name'))
  ..
});

Joi.validate(req.body, schema, function(err, value) {
  if (err) {
    console.log(err.message)
    return catched(err.message); 
  }
});

Answer 3

let schema = Joi.object({ foo: Joi.number().min(0).error(() => '"foo" requires a positive number') });

Docs link