# Tiny Validator (for v4 JSON Schema)

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Use [json-schema](http://json-schema.org/) [draft v4](http://json-schema.org/latest/json-schema-core.html) to validate simple values and complex objects using a rich [validation vocabulary](http://json-schema.org/latest/json-schema-validation.html) ([examples](http://json-schema.org/examples.html)).

There is support for `$ref` with JSON Pointer fragment paths (```other-schema.json#/properties/myKey```).

## Usage 1: Simple validation

```javascript
var valid = tv4.validate(data, schema);
```

If validation returns ```false```, then an explanation of why validation failed can be found in ```tv4.error```.

The error object will look something like:
```json
{
    "code": 0,
    "message": "Invalid type: string",
    "dataPath": "/intKey",
    "schemaPath": "/properties/intKey/type"
}
```

The `"code"` property will refer to one of the values in `tv4.errorCodes` - in this case, `tv4.errorCodes.INVALID_TYPE`.

To enable external schema to be referenced, you use:
```javascript
tv4.addSchema(url, schema);
```

If schemas are referenced (```$ref```) but not known, then validation will return ```true``` and the missing schema(s) will be listed in ```tv4.missing```. For more info see the API documentation below.

## Usage 2: Multi-threaded validation

Storing the error and missing schemas does not work well in multi-threaded environments, so there is an alternative syntax:

```javascript
var result = tv4.validateResult(data, schema);
```

The result will look something like:
```json
{
    "valid": false,
    "error": {...},
    "missing": [...]
}
```

## Usage 3: Multiple errors

Normally, `tv4` stops when it encounters the first validation error.  However, you can collect an array of validation errors using:

```javascript
var result = tv4.validateMultiple(data, schema);
```

The result will look something like:
```json
{
    "valid": false,
    "errors": [
        {...},
        ...
    ],
    "missing": [...]
}
```

## Asynchronous validation

Support for asynchronous validation (where missing schemas are fetched) can be added by including an extra JavaScript file.  Currently, the only version requires jQuery (`tv4.async-jquery.js`), but the code is very short and should be fairly easy to modify for other libraries (such as MooTools).

Usage:

```javascript
tv4.validate(data, schema, function (isValid, validationError) { ... });
```

`validationError` is simply taken from `tv4.error`.

## Cyclical JavaScript objects

While they don't occur in proper JSON, JavaScript does support self-referencing objects. Any of the above calls support an optional third argument: `checkRecursive`. If true, tv4 will handle self-referencing objects properly - this slows down validation slightly, but that's better than a hanging script.

Consider this data, notice how both `a` and `b` refer to each other:

```javascript
var a = {};
var b = { a: a };
a.b = b;
var aSchema = { properties: { b: { $ref: 'bSchema' }}};
var bSchema = { properties: { a: { $ref: 'aSchema' }}};
tv4.addSchema('aSchema', aSchema);
tv4.addSchema('bSchema', bSchema);
```

If the `checkRecursive` argument were missing, this would throw a "too much recursion" error.

To enable support for this, pass `true` as additional argument to any of the regular validation methods:

```javascript
tv4.validate(a, aSchema, true);
tv4.validateResult(data, aSchema, true);
tv4.validateMultiple(data, aSchema, true);
```

## The `banUnknownProperties` flag

Sometimes, it is desirable to flag all unknown properties as an error.  This is especially useful during development, to catch typos and the like, even when extra custom-defined properties are allowed.

As such, tv4 implements ["ban unknown properties" mode](https://github.com/json-schema/json-schema/wiki/ban-unknown-properties-mode-\(v5-proposal\)), enabled by a fourth-argument flag:

```javascript
tv4.validate(data, schema, checkRecursive, true);
tv4.validateResult(data, schema, checkRecursive, true);
tv4.validateMultiple(data, schema, checkRecursive, true);
```

## API

There are additional api commands available for more complex use-cases:

##### addSchema(uri, schema)
Pre-register a schema for reference by other schema and synchronous validation.

````js
tv4.addSchema('http://example.com/schema', { ... });
````

* `uri` the uri to identify this schema.
* `schema` the schema object.

Schemas that have their `id` property set can be added directly.

````js
tv4.addSchema({ ... });
````

##### getSchema(uri)

Return a schema from the cache.

* `uri` the uri of the schema (may contain a `#` fragment)

````js
var schema = tv4.getSchema('http://example.com/schema');
````

##### getSchemaMap()

Return a shallow copy of the schema cache, mapping schema document URIs to schema objects.

````
var map = tv4.getSchemaMap();

var schema = map[uri];
````

##### getSchemaUris(filter)

Return an Array with known schema document URIs.

* `filter` optional RegExp to filter URIs

````
var arr = tv4.getSchemaUris();

// optional filter using a RegExp
var arr = tv4.getSchemaUris(/^https?://example.com/);
````

##### getMissingUris(filter)

Return an Array with schema document URIs that are used as `$ref` in known schemas but which currently have no associated schema data.

Use this in combination with `tv4.addSchema(uri, schema)` to preload the cache for complete synchronous validation with.

* `filter` optional RegExp to filter URIs

````
var arr = tv4.getMissingUris();

// optional filter using a RegExp
var arr = tv4.getMissingUris(/^https?://example.com/);
````

##### dropSchemas()

Drop all known schema document URIs from the cache.

````
tv4.dropSchemas();
````

##### freshApi()

Return a new tv4 instance with no shared state.

````
var otherTV4 = tv4.freshApi();
````

##### reset()

Manually reset validation status from the simple `tv4.validate(data, schema)`. Although tv4 will self reset on each validation there are some implementation scenarios where this is useful.

````
tv4.reset();
````

##### setErrorReporter(reporter)

Sets a custom error reporter.  This is a function that accepts three arguments, and returns an error message (string):

```
tv4.setErrorReporter(function (error, data, schema) {
    return "Error code: " + error.code;
});
```

The `error` object already has everything aside from the `.message` property filled in (so you can use `error.params`, `error.dataPath`, `error.schemaPath` etc.).

If nothing is returned (or the empty string), then it falls back to the default error reporter.  To remove a custom error reporter, call `tv4.setErrorReporter(null)`.

##### language(code)

Sets the language used by the default error reporter.

* `code` is a language code, like `'en'` or `'en-gb'`

````
tv4.language('en-gb');
````

If you specify a multi-level language code (e.g. `fr-CH`), then it will fall back to the generic version (`fr`) if needed.

##### addLanguage(code, map)

Add a new template-based language map for the default error reporter (used by `tv4.language(code)`)

* `code` is new language code
* `map` is an object mapping error IDs or constant names (e.g. `103` or `"NUMBER_MAXIMUM"`) to language strings.

````
tv4.addLanguage('fr', { ... });

// select for use
tv4.language('fr')
````

If you register a multi-level language code (e.g. `fr-FR`), then it will also be registered for plain `fr` if that does not already exist.

##### addFormat(format, validationFunction)

Add a custom format validator. (There are no built-in format validators. Several common ones can be found [here](https://github.com/ikr/tv4-formats) though)

* `format` is a string, corresponding to the `"format"` value in schemas.
* `validationFunction` is a function that either returns:
  * `null` (meaning no error)
  * an error string (explaining the reason for failure)

````
tv4.addFormat('decimal-digits', function (data, schema) {
	if (typeof data === 'string' && !/^[0-9]+$/.test(data)) {
		return null;
	}
	return "must be string of decimal digits";
});
````

Alternatively, multiple formats can be added at the same time using an object:
````
tv4.addFormat({
	'my-format': function () {...},
	'other-format': function () {...}
});
````

##### defineKeyword(keyword, validationFunction)

Add a custom keyword validator.

* `keyword` is a string, corresponding to a schema keyword
* `validationFunction` is a function that either returns:
  * `null` (meaning no error)
  * an error string (explaining the reason for failure)
  * an error object (containing some of: `code`/`message`/`dataPath`/`schemaPath`)

````
tv4.defineKeyword('my-custom-keyword', function (data, value, schema) {
	if (simpleFailure()) {
		return "Failure";
	} else if (detailedFailure()) {
		return {code: tv4.errorCodes.MY_CUSTOM_CODE, message: {param1: 'a', param2: 'b'}};
	} else {
		return null;
	}
});
````

`schema` is the schema upon which the keyword is defined.  In the above example, `value === schema['my-custom-keyword']`.

If an object is returned from the custom validator, and its `message` is a string, then that is used as the message result.  If `message` is an object, then that is used to populate the (localisable) error template.

##### defineError(codeName, codeNumber, defaultMessage)

Defines a custom error code.

* `codeName` is a string, all-caps underscore separated, e.g. `"MY_CUSTOM_ERROR"`
* `codeNumber` is an integer > 10000, which will be stored in `tv4.errorCodes` (e.g. `tv4.errorCodes.MY_CUSTOM_ERROR`)
* `defaultMessage` is an error message template to use (assuming translations have not been provided for this code)

An example of `defaultMessage` might be: `"Incorrect moon (expected {expected}, got {actual}"`).  This is filled out if a custom keyword returns a object `message` (see above).  Translations will be used, if associated with the correct code name/number.

## Demos

### Basic usage

var schema = {
	"items": {
		"type": "boolean"
	}
};
var data1 = [true, false];
var data2 = [true, 123];

alert("data 1: " + tv4.validate(data1, schema)); // true
alert("data 2: " + tv4.validate(data2, schema)); // false
alert("data 2 error: " + JSON.stringify(tv4.error, null, 4));

### Use of $ref

var schema = {
	"type": "array",
	"items": {"$ref": "#"}
};
var data1 = [[], [[]]];
var data2 = [[], [true, []]];

alert("data 1: " + tv4.validate(data1, schema)); // true
alert("data 2: " + tv4.validate(data2, schema)); // false

### Missing schema

var schema = {
	"type": "array",
	"items": {"$ref": "http://example.com/schema" }
};
var data = [1, 2, 3];

alert("Valid: " + tv4.validate(data, schema)); // true
alert("Missing schemas: " + JSON.stringify(tv4.missing));

### Referencing remote schema

tv4.addSchema("http://example.com/schema", {
	"definitions": {
		"arrayItem": {"type": "boolean"}
	}
});
var schema = {
	"type": "array",
	"items": {"$ref": "http://example.com/schema#/definitions/arrayItem" }
};
var data1 = [true, false, true];
var data2 = [1, 2, 3];

alert("data 1: " + tv4.validate(data1, schema)); // true
alert("data 2: " + tv4.validate(data2, schema)); // false

## Supported platforms

* Node.js
* All modern browsers
* IE >= 7

## Installation

You can manually download [`tv4.js`](https://raw.github.com/geraintluff/tv4/master/tv4.js) or the minified [`tv4.min.js`](https://raw.github.com/geraintluff/tv4/master/tv4.min.js) and include it in your html to create the global `tv4` variable.

Alternately use it as a CommonJS module:

````js
var tv4 = require('tv4');
````

or as an AMD module (e.g. with requirejs):

```js
require('tv4', function(tv4){
  //use tv4 here
});
```

There is a command-line tool that wraps this library: [tv4-cmd](https://www.npmjs.com/package/tv4-cmd).

#### npm

````
$ npm install tv4
````

#### bower

````
$ bower install tv4
````

#### component.io

````
$ component install geraintluff/tv4
````

## Build and test

You can rebuild and run the node and browser tests using node.js and [grunt](http://http://gruntjs.com/):

Make sure you have the global grunt cli command:
````
$ npm install grunt-cli -g
````

Clone the git repos, open a shell in the root folder and install the development dependencies:

````
$ npm install
````

Rebuild and run the tests:
````
$ grunt
````

It will run a build and display one Spec-style report for the node.js and two Dot-style reports for both the plain and minified browser tests (via phantomJS). You can also use your own browser to manually run the suites by opening [`test/index.html`](http://geraintluff.github.io/tv4/test/index.html) and [`test/index-min.html`](http://geraintluff.github.io/tv4/test/index-min.html).

## Contributing

Pull-requests for fixes and expansions are welcome. Edit the partial files in `/source` and add your tests in a suitable suite or folder under `/test/tests` and run `grunt` to rebuild and run the test suite. Try to maintain an idiomatic coding style and add tests for any new features. It is recommend to discuss big changes in an Issue.

Do you speak another language? `tv4` needs internationalisation - please contribute language files to `/lang`!

## Packages using tv4

* [chai-json-schema](http://chaijs.com/plugins/chai-json-schema) is a [Chai Assertion Library](http://chaijs.com) plugin to assert values against json-schema.
* [grunt-tv4](http://www.github.com/Bartvds/grunt-tv4) is a plugin for [Grunt](http://http://gruntjs.com/) that uses tv4 to bulk validate json files.

## License

The code is available as "public domain", meaning that it is completely free to use, without any restrictions at all.  Read the full license [here](http://geraintluff.github.com/tv4/LICENSE.txt).

It's also available under an [MIT license](http://jsonary.com/LICENSE.txt).
