# is-my-json-valid
A [JSONSchema](http://json-schema.org/) validator that uses code generation
to be extremely fast
```
npm install is-my-json-valid
```
It passes the entire JSONSchema v4 test suite except for `remoteRefs` and `maxLength`/`minLength` when using unicode surrogate pairs.
[](http://travis-ci.org/mafintosh/is-my-json-valid)
## Usage
Simply pass a schema to compile it
``` js
var validator = require('is-my-json-valid')
var validate = validator({
required: true,
type: 'object',
properties: {
hello: {
required: true,
type: 'string'
}
}
})
console.log('should be valid', validate({hello: 'world'}))
console.log('should not be valid', validate({}))
// get the last list of errors by checking validate.errors
// the following will print [{field: 'data.hello', message: 'is required'}]
console.log(validate.errors)
```
You can also pass the schema as a string
``` js
var validate = validator('{"type": ... }')
```
Optionally you can use the require submodule to load a schema from `__dirname`
``` js
var validator = require('is-my-json-valid/require')
var validate = validator('my-schema.json')
```
## Custom formats
is-my-json-valid supports the formats specified in JSON schema v4 (such as date-time).
If you want to add your own custom formats pass them as the formats options to the validator
``` js
var validate = validator({
type: 'string',
required: true,
format: 'only-a'
}, {
formats: {
'only-a': /^a+$/
}
})
console.log(validate('aa')) // true
console.log(validate('ab')) // false
```
## External schemas
You can pass in external schemas that you reference using the `$ref` attribute as the `schemas` option
``` js
var ext = {
required: true,
type: 'string'
}
var schema = {
$ref: '#ext' // references another schema called ext
}
// pass the external schemas as an option
var validate = validator(schema, {schemas: {ext: ext}})
validate('hello') // returns true
validate(42) // return false
```
## Filtering away additional properties
is-my-json-valid supports filtering away properties not in the schema
``` js
var filter = validator.filter({
required: true,
type: 'object',
properties: {
hello: {type: 'string', required: true}
},
additionalProperties: false
})
var doc = {hello: 'world', notInSchema: true}
console.log(filter(doc)) // {hello: 'world'}
```
## Verbose mode outputs the value on errors
is-my-json-valid outputs the value causing an error when verbose is set to true
``` js
var validate = validator({
required: true,
type: 'object',
properties: {
hello: {
required: true,
type: 'string'
}
}
}, {
verbose: true
})
validate({hello: 100});
console.log(validate.errors) // {field: 'data.hello', message: 'is the wrong type', value: 100, type: 'string'}
```
## Greedy mode tries to validate as much as possible
By default is-my-json-valid bails on first validation error but when greedy is
set to true it tries to validate as much as possible:
``` js
var validate = validator({
type: 'object',
properties: {
x: {
type: 'number'
}
},
required: ['x', 'y']
}, {
greedy: true
});
validate({x: 'string'});
console.log(validate.errors) // [{field: 'data.y', message: 'is required'},
// {field: 'data.x', message: 'is the wrong type'}]
```
## Error messages
Here is a list of possible `message` values for errors:
* `is required`
* `is the wrong type`
* `has additional items`
* `must be FORMAT format` (FORMAT is the `format` property from the schema)
* `must be unique`
* `must be an enum value`
* `dependencies not set`
* `has additional properties`
* `referenced schema does not match`
* `negative schema matches`
* `pattern mismatch`
* `no schemas match`
* `no (or more than one) schemas match`
* `has a remainder`
* `has more properties than allowed`
* `has less properties than allowed`
* `has more items than allowed`
* `has less items than allowed`
* `has longer length than allowed`
* `has less length than allowed`
* `is less than minimum`
* `is more than maximum`
## Performance
is-my-json-valid uses code generation to turn your JSON schema into basic javascript code that is easily optimizeable by v8.
At the time of writing, is-my-json-valid is the __fastest validator__ when running
* [json-schema-benchmark](https://github.com/Muscula/json-schema-benchmark)
* [cosmicreals.com benchmark](http://cosmicrealms.com/blog/2014/08/29/benchmark-of-node-dot-js-json-validation-modules-part-3/)
* [jsck benchmark](https://github.com/pandastrike/jsck/issues/72#issuecomment-70992684)
* [themis benchmark](https://cdn.rawgit.com/playlyfe/themis/master/benchmark/results.html)
* [z-schema benchmark](https://rawgit.com/zaggino/z-schema/master/benchmark/results.html)
If you know any other relevant benchmarks open a PR and I'll add them.
## License
MIT
