How to set Joi validations with custom messages?

Question

I was trying to set some validations with some custom messages in Joi. So, for example, I have discovered that when a string must have at least 3 characters we can use "string.min" key and associate this to a custom message. Example:

  username: Joi.string().alphanum().min(3).max(16).required().messages({
    "string.base": `Username should be a type of 'text'.`,
    "string.empty": `Username cannot be an empty field.`,
    "string.min": `Username should have a minimum length of 3.`,
    "any.required": `Username is a required field.`,
  }),

Now here is my question:

Question

// Code for question
  repeat_password: Joi.ref("password").messages({
    "string.questionHere": "Passwords must match each other...",
  }),

What method (questionHere) name need to set to repeat_password to be able to notify the user that passwords must match? I don't even know if Join.ref("something") accept .messages({...})...

If someone could please show me some help in the Joi docs, I haven't find anything yet by there...

Answer 1

What you are trying to find here is the error type. It can be found in the error object that the joi validate function returns. eg: error.details[0].type will give you what you are looking for.

Regarding your second question, Join.ref("something") doesn't accept .messages({...}). Here you can use valid in conjunction with ref.

eg:

const Joi = require('joi');

const schema = Joi.object({
        username: Joi.string().alphanum().min(3).max(16).required().messages({
            "string.base": `Username should be a type of 'text'.`,
            "string.empty": `Username cannot be an empty field.`,
            "string.min": `Username should have a minimum length of 3.`,
            "any.required": `Username is a required field.`,
          }),
          password: Joi.string().required(),
          password_repeat: Joi.any().valid(Joi.ref('password')).required().messages({
            "any.only" : "Password must match"
          })
});

const result = schema.validate({ username: 'abc', password: 'pass', password_repeat: 'pass1'});


// In this example result.error.details[0].type is "any.only"