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v0.6.6-2
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JSON-Schema validator built for speed
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jsen (JSON Sentinel) validates your JSON objects using JSON-Schema.
Website: http://bugventure.github.io/jsen
Table of Contents
- Getting Started
- Performance & Benchmarks
- JSON Schema
- Format Validation
- External Schemas
- Errors
- Gathering Default Values
- In-Browser Usage
- Tests
- Contributing
- Issues
- Changelog
- License
Getting Started
Install through NPM in node.
$ npm install jsen --save
var jsen = require('jsen');
var validate = jsen({ type: 'string' });
var valid = validate('some value'); // true
Install through Bower in your HTML page.
$ bower install jsen
<script src="bower_components/jsen/dist/jsen.min.js"></script>
<script>
var validate = jsen({ type: 'string' }); // under window.jsen
var valid = validate('some value'); // true
</script>
Validation works by passing a JSON schema to build a validator function that can be used to validate a JSON object.
The validator builder function (jsen
) throws an error if the first parameter is not a schema object:
try {
// cannot use this string as a schema
jsen('not a valid schema');
}
catch (e) {
console.log(e);
}
jsen
will not throw an error if the provided schema is not compatible with the JSON-schema version 4 spec. In this case, as per the spec, validation will always succeed for every schema keyword that is incorrectly defined.
// this will not throw, but validation will be incorrect
var validate = jsen({ type: 'object', properties: ['string', 'number'] });
// validation erroneously passes, because keyword `properties` is ignored
var valid = validate({}); // true
If you need to validate your schema object, you can use a reference to the JSON meta schema. Internally, jsen
will recognize and validate against the metaschema.
var validateSchema = jsen({"$ref": "http://json-schema.org/draft-04/schema#"});
var isSchemaValid = validateSchema({ type: 'object' }); // true
isSchemaValid = validateSchema({
type: 'object',
properties: ['string', 'number']
});
// false, because properties is not in correct format
Performance & Benchmarks
JSEN uses dynamic code generation to produce a validator function that the V8 engine can optimize for performance. Following is a set of benchmarks where JSEN is compared to other JSON Schema validators for node.
More on V8 optimization: Performance Tips for JavaScript in V8
JSON Schema
To get started with JSON Schema, check out the JSEN schema guide.
For further reading, check out this excellent guide to JSON Schema by Michael Droettboom, et al.
JSEN fully implements draft 4 of the JSON Schema specification.
Format Validation
JSEN supports a few built-in formats, as defined by the JSON Schema spec:
date-time
uri
email
ipv4
ipv6
hostname
These formats are validated against string values only. As per the spec, format validation passes successfully for any non-string value.
var schema = { format: 'uri' },
validate = jsen(schema);
validate('invalid/uri'); // false - format validation kicks in for strings
validate({}); // true - does not kick in for non-strings
Custom Formats
JSEN additionally supports custom format validation. Custom formats are passed in options.formats
as a second argument to the jsen
validator builder function.
var schema = { format: 'uuid' },
uuidRegex = '^[a-fA-F0-9]{8}-[a-fA-F0-9]{4}-4[a-fA-F0-9]{3}-[89abAB][a-fA-F0-9]{3}-[a-fA-F0-9]{12}$',
validate = jsen(schema, {
formats: {
uuid: uuidRegex
}
});
validate('fad2b4f5-bc3c-44ca-8e17-6d30cf62bdb1'); // true
validate('not-a-valid-UUID'); // false
A custom format validator can be specified as:
- a regular expression
string
- a regular expression
object
- a
function (value, schema)
that must return a truthy value if validation passes
Unlike built-in format validators, custom format validators passed in the options
are run for all data types, not only strings. This allows implementing custom validation behavior for arrays and objects in scenarios, where it is not possible or practical to use only JSON Schema keywords for validation rules.
Custom format validation runs after all built-in keyword validators. This means that an error in any previous keyword validator will stop execution and any custom format validators won't run.
External Schemas
You can use references to external schema objects through the $ref
keyword. You pass external schemas in the options.schemas
object:
var external = { type: 'string' },
schema = { $ref: '#external' },
validate = jsen(schema, {
schemas: {
external: external
}
});
validate('abc'); // true
validate(123); // false
If you expect to have $ref
s pointing to missing schemas, you can tell JSEN to ignore invalid schema references with the options.missing$Ref
flag.
var schema = { $ref: '#missing' },
validate;
validate = jsen(schema); // Error: jsen: invalid schema reference #missing
validate = jsen(schema, { // OK, will ignore missing references
missing$Ref: true
})
Remote Schemas
Although JSEN does not automatically fetch remote schemas by making HTTP requests, you can fetch and provide them through the schemas
option by giving their URIs as object keys.
var schema = { $ref: 'http://localhost:1234/integer.json' },
externalSchema = { type: 'integer' }, // Downloaded from http://localhost:1234/integer.json
validate = jsen(schema, {
schemas: {
'http://localhost:1234/integer.json': externalSchema
}
});
Errors
The validator function (the one called with the object to validate) provides an errors
array containing all reported errors in a single validation run.
var validate = jsen({ type: 'string' });
validate(123); // false
console.log(validate.errors)
// Output: [{ path: '', keyword: 'type' }]
// path - deep (dot-delimited) path to the property that failed validation
// keyword - the JSON schema keyword that failed validation
validate('abc'); // true
// Output: []
The errors
array may contain multiple errors from a single run.
var validate = jsen({
anyOf: [
{
type: 'object',
properties: {
tags: { type: 'array' }
}
},
{
type: 'object',
properties: {
comment: { minLength: 1 }
}
}
]
});
validate({ tags: null, comment: '' });
console.log(validate.errors);
/* Output:
[ { path: 'tags', keyword: 'type' },
{ path: 'comment', keyword: 'minLength' },
{ path: '', keyword: 'anyOf' } ]
*/
When the additionalProperties
keyword fails validation, the respective error object contains a key by the same name, specifying the property name that was found in the validated object, but was fobidden in the schema:
var schema = {
properties: { foo: {} },
additionalProperties: false
}
var validate = jsen(schema);
validate({ foo: 'foo', bar: 'bar' }); // false
console.log(validate.errors);
/* Output:
[ { path: '',
keyword: 'additionalProperties',
additionalProperties: 'bar' } ]
*/
The errors array is replaced on every call of the validator function. You can safely modify the array without affecting successive validation runs.
Custom Errors
You can define your custom error messages in the schema object through the invalidMessage
and requiredMessage
keywords.
var schema = {
type: 'object',
properties: {
username: {
type: 'string',
minLength: 5,
invalidMessage: 'Invalid username',
requiredMessage: 'Username is required'
}
},
required: ['username']
};
var validate = jsen(schema);
validate({});
console.log(validate.errors);
/* Output:
[ { path: 'username',
keyword: 'required',
message: 'Username is required' } ]
*/
validate({ username: '' });
console.log(validate.errors);
/* Output:
[ { path: 'username',
keyword: 'minLength',
message: 'Invalid username' } ]
*/
Custom error messages are assigned to error objects by path, meaning multiple failed JSON schema keywords on the same path will show the same custom error message.
var schema = {
type: 'object',
properties: {
age: {
type: 'integer',
minimum: 0,
maximum: 100,
invalidMessage: 'Invalid age specified'
}
}
};
var validate = jsen(schema);
validate({ age: 13.3 });
console.log(validate.errors);
/* Output:
[ { path: 'age',
keyword: 'type',
message: 'Invalid age specified' } ]
*/
validate({ age: -5 });
console.log(validate.errors);
/* Output:
[ { path: 'age',
keyword: 'minimum',
message: 'Invalid age specified' } ]
*/
validate({ age: 120 });
console.log(validate.errors);
/* Output:
[ { path: 'age',
keyword: 'maximum',
message: 'Invalid age specified' } ]
*/
The requiredMessage
is assigned to errors coming from the required
and dependencies
keywords. For all other validation keywords, the invalidMessage
is used.
Custom Errors for Keywords
You can assign custom error messages to keywords through the messages
object in the JSON schema.
var schema = {
type: 'object',
messages: {
type: 'Invalid data type where an object is expected'
}
}
var validate = jsen(schema);
validate('this is a string, not an object');
console.log(validate.errors);
/* Output:
[ { path: '',
keyword: 'type',
message: 'Invalid data type where an object is expected' } ]
*/
NOTE: The following keywords are never assigned to error objects, and thus do not support custom error messages: items
, properties
, patternProperties
, dependecies
(when defining a schema dependency) and allOf
.
Greedy Validation
For performance, by default, JSEN returns the first encountered error and bails out any further execution.
With the options.greedy
flag passed to the builder function, the compiled validator will try to validate as much as possible, providing more info in the errors
array.
var schema = {
type: 'object',
properties: {
firstName: {
type: 'string',
minLength: 1,
maxLength: 20
},
lastName: {
type: 'string',
minLength: 2,
maxLength: 50
},
age: {
type: 'number',
minimum: 18,
maximum: 100
}
},
required: ['firstName', 'lastName', 'age']
};
var validate = jsen(schema, { greedy: true }); // enable greedy validation
validate({ firstName: null, lastName: '' });
console.log(validate.errors);
/* Output:
[ { path: 'firstName', keyword: 'type' },
{ path: 'lastName', keyword: 'minLength' },
{ path: 'age', keyword: 'required' } ]
*/
Gathering Default Values
JSEN can collect default values from the schema. The build(initial, options)
method in the dynamic validator function recursively walks the schema object and compiles the default values into a single object or array.
var validate = jsen({ type: 'string', default: 'abc' });
console.log(validate.build()); // 'abc'
var validate = jsen({
default: {},
properties: {
foo: { default: 'bar' },
arr: {
default: [],
items: [
{ default: 1 },
{ default: 1 },
{ default: 2 }
]
}
}
});
console.log(validate.build()); // { foo: 'bar', arr: [1, 2, 3] }
The build
function can additionally merge the default values with an initially provided data object.
var validate = jsen({
properties: {
rememberMe: {
default: 'true'
}
}
});
var initial = { username: 'John', password: 'P@$$w0rd' };
initial = validate.build(initial);
console.log(initial);
// { username: 'John', password: 'P@$$w0rd', rememberMe: true }
options.copy
By default, the build
function creates a copy of the initial data object. You can opt to modify the object in-place by passing { copy: false }
as a second argument.
var initial = { username: 'John', password: 'P@$$w0rd' };
var validate = jsen({
properties: {
rememberMe: {
default: 'true'
}
}
});
var withDefaults = validate.build(initial);
console.log(withDefaults === initial); // false (initial is cloned)
withDefaults = validate.build(initial, { copy: false });
console.log(withDefaults === initial); // true (initial is modified)
options.additionalProperties
The JSON schema spec allows additional properties by default. In many cases, however, this default behavior may be undesirable, forcing developers to specify additionalProperties: false
everywhere in their schema objects. JSEN's build
function can filter out additional properties by specifying { additionalProperties: false }
as a second argument.
var validate = jsen({
properties: {
foo: {},
bar: {}
}
});
var initial = { foo: 1, bar: 2, baz: 3};
initial = validate.build(initial, { additionalProperties: false });
console.log(initial); // { foo: 1, bar: 2 }
When both options.additionalProperties
and schema.additionalProperties
are specified, the latter takes precedence.
var validate = jsen({
additionalProperties: true,
properties: {
foo: {},
bar: {}
}
});
var initial = { foo: 1, bar: 2, baz: 3};
initial = validate.build(initial, { additionalProperties: false });
console.log(initial); // { foo: 1, bar: 2, baz: 3 }
NOTE: When { additionalProperties: false, copy: false }
is specified in the build
options, any additional properties will be deleted from the initial data object.
In some scenarios, you may want to disallow additional properties in the schema, but still keep them when gathering default values with build()
. This may be required, for example, when you want to explicitly fail validation and display a message to the user, listing any excessive properties that are forbidden by the schema. Setting { additionalProperties: 'always' }
will prevent the build()
function from removing any properties in the initial object.
var schema = {
additionalProperties: false,
properties: {
foo: {}
}
};
var initial = { foo: 1, bar: 2 };
var validate = jsen(schema);
var withDefaults = validate.build(initial, { additionalProperties: 'always' });
// withDefaults has both 'foo' and 'bar' keys
In-Browser Usage
Browser-compatible builds of jsen
(with the help of browserify) can be found in the dist
folder. These are built with the standalone option of browserify, meaning they will work in node, the browser with globals, and AMD loader environments. In the browser, the window.jsen
global object will refer to the validator builder function.
Load from CDN, courtesy of rawgit:
//cdn.rawgit.com/bugventure/jsen/v0.6.6/dist/jsen.js
//cdn.rawgit.com/bugventure/jsen/v0.6.6/dist/jsen.min.js
Tests
To run mocha tests in node:
[~/github/jsen] $ npm test
To run the same test suite in the browser, serve the test/index.html
page in your node web server and navitate to /test/
path from your browser. The example below uses node-static:
[~/github/jsen] $ npm install -g node-static
...
[~/github/jsen] $ static .
serving "." at http://127.0.0.1:8080
# navigate to http://127.0.0.1:8080/test/ in your browser
jsen
passes all draft 4 test cases specified by the JSON-Schema-Test-Suite with the exception of zero-terminated float tests.
Source code coverage is provided by istanbul and visible on coveralls.io.
Contributing
To contribute to the project, fork the repo, edit and send a Pull Request. Please adhere to the coding guidelines enforced by the jshint and jscs code checkers.
[~/github/jsen] $ jshint lib/ && jscs lib/
No code style errors found.
All tests must pass both in node and in the browser.
[~/github/jsen] $ npm test
To build the jsen browser-compatible distribution files, run:
[~/github/jsen] $ npm run build
This will update the files in the /dist
folder.
Issues
Please submit issues to the jsen issue tracker in GitHub.
Changelog
Read changelog.md