JJV: JJV JSON Validator

A simple and extensible json-schema validator written in javascript. JJV
runs in the browser and in the server (through node.js), it has no
dependencies and has out-of-the-box AMD support.

JJV implements the latest (v4) JSON Schema Core draft, however due to
performance and security concerns remote schemas are not fetched. To
ensure compliance JJV is tested against JSON Schema Test Suite published
by json-schema.org (and passes all tests). For examples and a detailed
description of the JSON-schema specification visit
json-schema.org.

JJV is fast! For a detailed performance comparison visit z-schema's
benchmarks
website, which compares various javascript JSON schema validators.

Basic Usage

In the most basic usage an environment must be created, and one or more
named schemas are registered in the environment (it is also possible to
register schemas with remote URI's in the same way). Javascript
objects can then be validated against any registered schema.

``javascript
// create new JJV environment
var env = jjv();

// Register a user schema
env.addSchema('user', {
type: 'object',
properties: {
firstname: {
type: 'string',
minLength: 2,
maxLength: 15
},
lastname: {
type: 'string',
minLength: 2,
maxLength: 25
},
gender: {
type: 'string',
enum: ['male', 'female']
},
email: {
type: 'string',
format: 'email'
},
password: {
type: 'string',
minLength: 8
}
},
required: ['firstname', 'lastname', 'email', 'password']
});

// Perform validation against an incomplete user object (errors will be reported)
var errors = env.validate('user', {firstname: 'John', lastname: 'Smith'});

// validation was successful
if (!errors) {
alert('User has been validated.')
} else {
alert('Failed with error object ' + JSON.stringify(errors));
}
`

It is also possible to validate objects against unregistered and/or
unnamed schemas by supplying the schema object directly. For example:

`javascript
var env = jjv();

var errors = env.validate({
type: 'object',
properties: {
x: {
type: 'number'
},
y: {
type: 'number'
}
},
required: ['x', 'y']
}, {x: 20, y: 50});

`

Validation Options

JJV provides options to control the validation of required fields, the
handling of default values, and the handling of additional properties.

The defaults can be overridden for the entire environment or on a
per-validation basis. For example, to override the checkRequired option
for the entire environment simply do:

`javascript
env.defaultOptions.checkRequired=false;
`

To override the checkRequired option on a per-validation case do:

`
env.validate('schemaName', object, {checkRequired: false});
`

Advanced Usage

JJV provides mechanisms to add support for custom types, custom formats,
and custom checks.

$3

Support for additional types can be added through the addType
function. For example, a simple implementation of the date type could
be the following:

`javascript
env.addType('date', function (v) {
return !isNan(Date.parse(v));
});
`

$3

It is also possible to add support for additional string formats through
the addFormat function. For example, an implementation of the
hexadecimal string format (already included) could be as follows:

`javascript
env.addFormat('hexadecimal', function (v) {
return (/^[a-fA-F0-9]+$/).test(v);
});
`

$3

It is possible to add support for custom checks (i.e.,
minItems, maxItems, minLength, maxLength, etc.) through the
addCheck function. For example, an implementation for an exactLength
validation keyword that supports arrays and strings can be achieved with
the following:

`javascript
env.addCheck('exactLength', function (v, p) {
return v.length === p;
});
`

$3

JJV allows custom type coercion rules. As an example, supposed that fields
which are declared with as type integer are sometimes encoded as a string.
Type coercion allows you to specify that all types declared as integer should
be cast/coerced to an integer before performing validation.

`javascript
env.addTypeCoercion('integer', function (x) {
return parseInt(x, 10);
});
`

Recall to set the option useCoerce to true to enable this feature.

$data v5 proposal

JJV supports the $data` spec proposed for draft 5 of json-schema,
complete with relative and absolute JSON pointers.

For information on how to use these feature see the proposal here:

$data-proposal).