hapi-format-validation

This Hapi plugin formats validation errors in a way that is consistent, simple, and easy to render in client-side forms. Take your typical Joi validation error reply for instance...

Before hapi-format-validation 😿

{
  statusCode: 400,
  error: 'Bad Request',
  // this message should get formatted before displaying it to a user
  message: 'child "name" fails because ["name" is not allowed to be empty]. child "email" fails because ["email" must be a valid email]',
  validation: {
    source: 'payload',
    // extra work required of the client to link these keys to error messages :(
    keys: [
      'name',
      'email'
    ]
  }
}

After hapi-format-validation 😍

{
  statusCode: 400,
  error: 'Bad Request',
  // a newline-separated string, ready-to-use if necessary
  message: '"name" is not allowed to be empty↵"email" must be a valid email',
  validation: {
    source: 'payload',
    // a simple key-value mapping of fields and their errors
    errors: {
      name: '"name" is not allowed to be empty',
      email: '"email" must be a valid email'
    }
  }
}

Installation

$ npm install --save hapi-format-validation

Usage

const FormatValidation = require('hapi-format-validation');

server.register(FormatValidation, err => {
  // server fun times
});

Options

• stripQuotes: (optional) if true, strips double quotation marks from around the path name in error messages
• capitalize: (optional) if true, capitalizes the first letter of each error message
• sequelize: (optional) pass a Sequelize instance to format unique key violations (more information below)

Sequelize integration

hapi-format-validation also handles Sequelize unique key violation errors, which would otherwise be a 500 Internal Server Error. Pass your Sequelize instance (sold separately) as an option to the plugin when you register it to enable this feature.

const FormatValidation = require('hapi-format-validation');
const Sequelize = require('sequelize');

const sequelize = new Sequelize(...);

server.register(
  {
    register: FormatValidation,
    options: {sequelize}
  },
  err => {
    // do your server stuff
  }
);

Before

{
  statusCode: 500,
  error: 'Internal Server Error',
  message: 'An internal server error occurred'
}

After

{
  'statusCode': 400,
  'error': 'Bad Request',
  'message': '"username" must be unique',
  'validation': {
    'source': 'payload',
    'errors': {
      'username': '"username" must be unique'
    }
  }
}

Acknowledgements 👊

• joi-errors-for-forms for the validation payload format inspiration
• This article by Andrey Viktorov for the idea around using the onPreResponse hook and checking for Sequelize errors