0.2.6 • Public • Published


    In order to keep a consistent validation API in your apps, convert the error objects returned by Joi to either

    • the { name1: text, name2: text } schema commonly used with form UIs, or
    • the Mongoose schema { name1: { message: ..., name: 'ValidatorError', path: ..., type: ... } }.

    The Joi error messages may be replaced either for internationalization or clarity.

    The package has no dependencies.

    Build Status

    Code Examples

    For the following Joi schema:

    const Joi = require('joi');
    const name = Joi.string().trim().regex(/^[\sa-zA-Z0-9]{5,30}$/).required();
    const password = Joi.string().trim().min(2).max(30).required();
    const schema = Joi.object().keys({
      confirmPassword: password.label('Confirm password'),
    const joiOptions = { convert: true, abortEarly: false };
    const values = { name: 'j', password: 'z', confirmPassword: 'z' };

    (1) Convert the Joi messages to the form UI schema, retaining the original message text.

    const joiToForms = require('joi-errors-for-forms').form;
    const convertToForms = joiToForms();
    Joi.validate(values, schema, joiOptions, (errs, convertedValues) => {
      // { name: '"name" with value "j" fails to match the required pattern: /^[\\sa-zA-Z0-9]{5,30}$/',
      //   password: '"password" length must be at least 2 characters long',
      //   confirmPassword: '"Confirm password" length must be at least 2 characters long'
      // }
      // or null if no errors.

    (2) Convert to the form UI schema. Replace Joi messages using Joi error types. (Recommended.)

    const joiToForms = require('joi-errors-for-forms').form;
    const convertToForms = joiToForms({
      'string.min': () => i18n('"${key}" must be ${limit} or more chars.'),
      'string.regex.base': (context) => {
        switch (context.pattern.toString()) {
          case /^[\sa-zA-Z0-9]{5,30}$/.toString():
            return i18n('"${key}" must consist of letters, digits or spaces.');
    Joi.validate(values, schema, joiOptions, (errs, convertedValues) => {
      // { name: '"name" must consist of letters, digits or spaces.',
      //   password: '"password" must be 2 or more chars.',
      //   confirmPassword: '"Confirm password" must be 2 or more chars.'
      // }
    function i18n(str) { return str; } // internationalization

    or convert to the Mongoose schema.

    const joiToMongoose = require('joi-errors-for-forms').mongoose;
    const convertToMongoose = joiToMongoose({
      ... same as above ...
    Joi.validate(values, schema, joiOptions, (errs, convertedValues) => {
      // { name: 
      //     { message: '"name" must consist of letters, digits or spaces.',
      //       name: 'ValidatorError',
      //       path: 'name',
      //       type: 'string.regex.base' },
      //   password: 
      //     { message: '"password" must be 2 or more chars.',
      //       name: 'ValidatorError',
      //       path: 'password',
      //       type: 'string.min' },
      //   confirmPassword: 
      //     { message: '"Confirm password" must be 2 or more chars.',
      //       name: 'ValidatorError',
      //       path: 'confirmPassword',
      //       type: 'string.min' }
      // }

    List of substitution tokens. Refer to Joi documentation for more information.

    • ${key} prop name, or label if .label('...') was used.
    • ${value} prop value. Its rudimentally converted to a string.
    • ${pattern} regex value if .regex(...) was involved in the error. Its converted to a string.
    • ${limit} allowed length of string.
    • ${encoding} string encoding. Could be undefined. Its converted to a string.

    Note that type retains the Joi value in the Mongoose schema. It is not converted to what Mongoose would return.

    (3) Replace Joi messages with a generic error message.

    const convertToForms = joiToForms('"${key}" is badly formed.');
    Joi.validate(values, schema, joiOptions, (errs, convertedValues) => {
      // { name: '"name" is badly formed.',
      //   password: '"password" is badly formed.',
      //   confirmPassword: '"Confirm password" is badly formed.'
      // }

    (4) Replace Joi messages, by searching for substrings in Joi messages.

    const convertToForms = joiToForms([
      { regex: 'at least 2 characters long',
        message: '"${key}" must be 2 or more chars.'
      { regex: /required pattern/,
        message: '"${key}" is badly formed.'
    Joi.validate(values, schema, joiOptions, (errs, convertedValues) => {
      // { name: '"name" is badly formed.',
      //   password: '"password" must be 2 or more chars.',
      //   confirmPassword: '"Confirm password" must be 2 or more chars.'
      // }


    Joi is an enterprise strength schema validator and sanitizer originally developed by Walmart.

    The error object it returns, however, usually has to be reformatted for use within web/mobile apps. Its error messages may also have to be converted for internationalization or for clarity.

    This package helps with both needs.


    Install Nodejs.

    Run npm install joi-errors-for-forms --save in your project folder.

    You can then require the package.

    // ES5
    var joiErrorsToForms = require('joi-errors-for-forms');
    var joiToForms = joiErrorsToForms.form;
    var joiToMongoose = joiErrorsToForms.mongoose;
    // or ES6
    import { form as joiToForms, mongoose as joiToMongoose } from 'joi-errors-for-forms';

    API Reference

    See Code Examples.


    npm test to run tests.

    A Note on Internationalization

    The options in Joi.validate(value, schema, options, cb)supports a language option with which you can change Joi error messages in bulk.

    You can then internationalize your field names and regex descriptions in the schema, e.g.

    Joi.string().regex(/^[\sa-zA-Z0-9]$/, i18n('letters, number and spaces')).label(i18n('Confirm password'))

    These are suitable methods to internationalize the majority of Joi error messages.





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