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is-my-json-valid

is-my-json-valid

A JSONSchema 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.

build status

Usage

Simply pass a schema to compile it

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

var validate = validator('{"type": ... }')

Optionally you can use the require submodule to load a schema from __dirname

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

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

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

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

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:

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

If you know any other relevant benchmarks open a PR and I'll add them.

License

MIT