better-ajv-errors

What is better-ajv-errors?

The better-ajv-errors package provides improved error messages for the AJV JSON schema validator. It helps developers understand validation errors more easily by presenting them in a more readable and user-friendly format.

What are better-ajv-errors's main functionalities?

Readable Error Messages

This feature provides more readable error messages when validation fails. The code sample demonstrates how to use better-ajv-errors to display a user-friendly error message when the data does not conform to the schema.

const Ajv = require('ajv');
const betterAjvErrors = require('better-ajv-errors');

const ajv = new Ajv();
const schema = {
  type: 'object',
  properties: {
    name: { type: 'string' },
    age: { type: 'integer' }
  },
  required: ['name', 'age']
};

const data = {
  name: 'John Doe',
  age: 'twenty-five'
};

const validate = ajv.compile(schema);
const valid = validate(data);

if (!valid) {
  const output = betterAjvErrors(schema, data, validate.errors, { format: 'js' });
  console.log(output);
}

Custom Error Formatting

This feature allows for custom formatting of error messages. The code sample shows how to format the error messages for command-line interface (CLI) output with indentation.

const Ajv = require('ajv');
const betterAjvErrors = require('better-ajv-errors');

const ajv = new Ajv();
const schema = {
  type: 'object',
  properties: {
    email: { type: 'string', format: 'email' }
  },
  required: ['email']
};

const data = {
  email: 'not-an-email'
};

const validate = ajv.compile(schema);
const valid = validate(data);

if (!valid) {
  const output = betterAjvErrors(schema, data, validate.errors, { format: 'cli', indent: 2 });
  console.log(output);
}

Other packages similar to better-ajv-errors

ajv-errors

The ajv-errors package allows for custom error messages in AJV. It provides a way to define custom error messages directly in the JSON schema, which can be useful for providing more context-specific error information. Unlike better-ajv-errors, which focuses on improving the readability of default error messages, ajv-errors allows for the customization of error messages at the schema level.

ajv-i18n

The ajv-i18n package provides internationalization (i18n) support for AJV error messages. It translates AJV error messages into different languages, making it useful for applications that need to support multiple languages. While better-ajv-errors focuses on making error messages more readable, ajv-i18n focuses on translating them into different languages.

README

JSON Schema validation for Human 👨‍🎤

Main goal of this library is to provide relevant error messages like the following:

Installation

$ npm i better-ajv-errors
$ # Or
$ yarn add better-ajv-errors

Also make sure that you installed ajv package to validate data against JSON schemas.

Usage

First, you need to validate your payload with ajv. If it's invalid then you can pass validate.errors object into better-ajv-errors.

import Ajv from 'ajv';
import betterAjvErrors from 'better-ajv-errors';
// const Ajv = require('ajv');
// const betterAjvErrors = require('better-ajv-errors').default;
// Or
// const { default: betterAjvErrors } = require('better-ajv-errors');

// You need to pass `{ jsonPointers: true }` for older versions of ajv
const ajv = new Ajv();

// Load schema and data
const schema = ...;
const data = ...;

const validate = ajv.compile(schema);
const valid = validate(data);

if (!valid) {
  const output = betterAjvErrors(schema, data, validate.errors);
  console.log(output);
}

API

betterAjvErrors(schema, data, errors, [options])

Returns formatted validation error to print in console. See options.format for further details.

schema

Type: Object

The JSON Schema you used for validation with ajv

data

Type: Object

The JSON payload you validate against using ajv

errors

Type: Array

Array of ajv validation errors

options

Type: Object

format

Type: string
Default: cli
Values: cli js

Use default cli output format if you want to print beautiful validation errors like following:

Or, use js if you are planning to use this with some API. Your output will look like following:

[
  {
    start: { line: 6, column: 15, offset: 70 },
    end: { line: 6, column: 26, offset: 81 },
    error:
      '/content/0/type should be equal to one of the allowed values: panel, paragraph, ...',
    suggestion: 'Did you mean paragraph?',
  },
];

indent

Type: number null
Default: null

If you have an unindented JSON payload and you want the error output indented.

This option have no effect when using the json option.

json

Type: string null
Default: null

Raw JSON payload used when formatting codeframe. Gives accurate line and column listings.