ajv-keywords

What is ajv-keywords?

The ajv-keywords package extends AJV (Another JSON Schema Validator) with additional keywords for JSON schema validation. It allows for more complex validation scenarios beyond what is available in the standard JSON Schema.

What are ajv-keywords's main functionalities?

dynamicDefaults

Allows setting dynamic defaults for properties, such as generating timestamps for createdAt fields.

{"properties": {"createdAt": {"type": "string", "format": "date-time", "default": "dynamic", "dynamicDefault": "datetime"}}}

transform

Enables transformation of data before validation. For example, trimming whitespace and converting text to lowercase.

{"properties": {"email": {"type": "string", "transform": ["trim", "toLowerCase"]}}}

range

Introduces exclusive range validation for numeric values, allowing for minimum and maximum values to be exclusive.

{"properties": {"age": {"type": "number", "exclusiveRange": true, "minimum": 18, "maximum": 60}}}

Other packages similar to ajv-keywords

jsonschema

A JSON Schema validator that supports draft-04/06/07. It's similar to ajv-keywords in providing JSON schema validation but does not offer the same level of keyword extension for custom validation scenarios.

tv4

Tiny Validator (tv4) is a lightweight JSON Schema validator that supports draft-04. While it provides basic validation capabilities, it lacks the extensibility and additional keywords provided by ajv-keywords.

README

ajv-keywords

Custom JSON-Schema keywords for ajv validator

Install

npm install ajv-keywords

Usage

var Ajv = require('ajv');
var defineKeywords = require('ajv-keywords');

var ajv = new Ajv;
defineKeywords(ajv, 'instanceof');

ajv.validate({ instanceof: 'RegExp' }, /.*/); // true
ajv.validate({ instanceof: 'RegExp' }, '.*'); // false

or if using in browser (to avoid adding unused code):

var Ajv = require('ajv');
var ajv = new Ajv;
var instanceofDefinition = require('ajv-keywords/keywords/instanceof')
ajv.addKeyword('instanceof', instanceofDefinition);

Keywords

typeof

Based on JavaScript typeof operation.

The value of the keyword should be a string: "undefined", "string", "number", "object", "function", "boolean" or "symbol".

To pass validation the result of typeof operation on the value should be equal to the string.

ajv.validate({ typeof: 'undefined' }, undefined); // true
ajv.validate({ typeof: 'undefined' }, null); // false

instanceof

Based on JavaScript typeof operation.

The value of the keyword should be a string: "Object", "Array", "Function", "Number", "String", "Date", "RegExp" or "Buffer".

To pass validation the result of data instanceof ... operation on the value should be true:

ajv.validate({ instanceof: 'Array' }, []); // true
ajv.validate({ instanceof: 'Array' }, {}); // false

You can add your own constructor function to be recognised by this keyword:

function MyClass() {}
instanceofDefinition.CONSTRUCTORS.MyClass = MyClass;

ajv.validate({ instanceof: 'MyClass' }, new MyClass); // true

License

MIT