jski - json schema validator

JSON Schema support

jski validates a subset of json schema v4. Following features are missing or restricted:

• no union types
• array: additionalItems can only be true or false, not a schema
• object: additionalProperties can only be true or false
• object: no patternProperties
• object: no dependencies
• $ref: definitions are solely looked up by name in options.definitions or jski.object({...}).defintions({...})
• not: not supported

Installation

npm install jski

Usage

var J = require('jski')();

Examples

Create schema using method chaining

 
var J = require('jski')();
 
var validator = J.object({
  foo: J.number(),
  bar: J.string().maxLength(255)
});
 
var errs = validator.validate({ foo: 11, bar: 'hello' });
 

Create validator from json

 
var J = require('jski')();
 
var js = {
  foo: { type: 'number' },
  bar: { type: 'string', maxLength: 255 }
};
 
var validator = J.createValidator(js);
 
var errs = validator.validate({ foo: true, bar: 'hello' });
 

Get schema in json form

 
var J = require('jski')();
 
var json = J.object({ foo: J.string() }).toJSON();
 

API

Building schemas with method chaining

Types

• J.boolean()
• J.number().minimum(1).maximum(10).multipleOf()
• J.integer() - Same as number
• J.string().minLength(1).maxLength(10).pattern('[0-9]*').format('email')
• J.array(J.number()).minItems(1).maxItems(10).uniqueItems(true).additionalItems(false)
• J.array(J.number(), J.string(), J.boolean())
• J.object({ foo: J.number() }).minProperties(1).maxProperties(10).required('foo', 'bar').additionalProperties(false)
• J.enum(1, 2, 3)
• J.any()
• J.null()
• J.allOf(schema1, schema2, schema3)
• J.anyOf(schema1, schema2, schema3)
• J.oneOf(schema1, schema2, schema3)

Common methods available to all types

• J.number().title('foo').description('bar').default(11)

Validation

validate(value, options) returns an error array. When the value is valid, the array is empty.

• var errors = J.number().maximum(127).validate(128)

Definitions

Add Defintions:

• by method: J.object({...}).definitions({...})
• by options: var errors = J.object({...}).validate({...}, { definitions: {...} })

Serializing schemas from/to JSON

• J.createValidator(Schema JSON)
• J.object({ foo: j.string() }).toJSON()

Create a default value for a schema

• J.createValue(J.number())
• J.createValue({ type: 'number' })

Options

J.object().validate(value, { definitions: defs, omitRefs: true })

• definitions - Dict where $refs are lookuped by name
• omitRefs - Do not validate $refs

Add mixins for validators

Simple way to reuse definitions without using an actual $ref

var validator = J
  .mixin('foo', J.object({ bar: J.string() }))
  .mixin('bar', J.object({ baz: J.number() }))
  .object({
    un: J.foo(),
    dos: J.bar()
  });

Validator context

var J = require('jski)();
var v1 = J.object({ foo: J.string() });
assert(v1.context === J);

Errors

Error messages look like:

{ message: "Value is too long", code: "maxLength", path: "foo.bar[0].baz" }