# Schema

Module used to validate structures.

Access it with:
```javascript
const { Schema } = Neft;
```

    'use strict'

    utils = require 'src/utils'
    assert = require 'src/assert'

## **Class** SchemaError()

Raised by `Schema::validate()` if given data doesn't pass the schema.

Access it with:
```javascript
var Schema = require('schema');
var SchemaError = Schema.Error;
```

    class SchemaError extends Error
        constructor: (@property, @validator, @message) -> super

        name: 'SchemaError'
        message: ''

    module.exports = class Schema
        @Error = SchemaError

## Schema::constructor(*Object* schema)

Creates a new Schema instance used to validate data.

Specify schema validators for each of the accepted property.

```javascript
new Schema({
    address: {
        type: 'string'
    },
    delivery: {
        optional: true,
        type: 'boolean'
    }
});
```

        constructor: (@schema) ->
            assert.isPlainObject @schema

            assert.notOk utils.isEmpty(@schema)
            , "Schema: schema can't be empty"

            for row, elem of @schema
                assert utils.isPlainObject(elem)
                , "Schema: schema for #{row} row is not an object"

            Object.preventExtensions @

## *Object* Schema::schema

Saved schema object from the constructor.

It's allowed to change this object in runtime.

        schema: null

## *Boolean* Schema::validate(*Object* data)

Validates the given data object by the schema.

Returns `true` if the data is valid, otherwise throws an SchemaError instance.

```javascript
var schema = new Schema({
  age: {
    type: 'number',
    min: 0,
    max: 200
  }
});

console.log(utils.catchError(schema.validate, schema, [{}])+'');
// "SchemaError: Required property age not found"

console.log(utils.catchError(schema.validate, schema, [{name: 'Jony'}])+'');
// "SchemaError: Unexpected name property"

console.log(utils.catchError(schema.validate, schema, [{age: -5}])+'');
// "SchemaError: Minimum range of age is 0"

console.log(schema.validate({age: 20}));
// true

console.log(utils.tryFunction(schema.validate, schema, [{age: -1}], false));
// false

console.log(utils.tryFunction(schema.validate, schema, [{age: 5}], false));
// true
```

### Nested properties

Use dot in the property name to valdiate deep objects.

```javascript
var schema = new Schema({
  obj: {
    type: 'object'
  },
  'obj.prop1.name': {
    type: 'string'
  }
});

console.log(utils.catchError(schema.validate, schema, [{obj: {prop1: {name: 123}}}])+'');
// "SchemaError: obj.prop1.name must be a string"

console.log(schema.validate({obj: {prop1: {name: 'Lily'}}}));
// true
```

This function uses *utils.get()* internally.

```javascript
var schema = new Schema({
  names: {
    array: true
  },
  'names[]': {
    type: 'string'
  }
});

console.log(utils.catchError(schema.validate, schema, [{names: [123, null]}])+'');
// "SchemaError: names[] must be a string"

console.log(schema.validate({names: ['Lily', 'Max']}));
// true
```

        validators =
            array: require('./validators/array') Schema
            object: require('./validators/object') Schema
            optional: require('./validators/optional') Schema
            max: require('./validators/max') Schema
            min: require('./validators/min') Schema
            options: require('./validators/options') Schema
            regexp: require('./validators/regexp') Schema
            type: require('./validators/type') Schema

        validate: (data) ->
            assert.isNotPrimitive data

            # check if there is no unprovided rows
            for row of data
                unless @schema.hasOwnProperty row
                    throw new SchemaError row, null, "Unexpected #{row} property"

            # by rows
            for row, rowValidators of @schema
                # get current value
                # add support for string referecing into sub-properties and
                # multiple values by `utils.get()`
                values = utils.get data, row

                if not values?
                    if rowValidators.optional
                        continue
                    throw new SchemaError row, 'optional', "Required property #{row} not found"

                # by validators
                for validatorName, validatorOpts of rowValidators
                    validator = validators[validatorName]

                    assert validator, "Schema validator #{validatorName} not found"

                    if values instanceof utils.get.OptionsArray
                        for value, i in values
                            validator row, value, validatorOpts
                    else
                        validator row, values, validatorOpts

            true