Validator

Data validator

Example

const {createValidator} = require('@ololoepepe/validator');
const DB = require('../lib/database');

const UserValidator = createValidator({
  type: 'object',
  fields: {
    nickname: {
      type: 'string',           // Nickname must be a string
      minLength: 4,                   // with a minimum length of 4
      maxLength: 20,                  // and maximum length of 20
      regexp: /^[a-zA-Z0-9_]+$/ // consisting of latin letters, digits and underscores
    },
    password: {
      type: 'string', // password must be a string
      minLength: 8,         // with a minimum length of 8
      maxLength: 32,        // and maximum length of 32
      validate: (pwd, done) => {
        // A password must contain at least one digin
        if (!/[0-9]/.test(pwd)) {
          done({code: 'PASSWORD_HAS_NO_DIGITS'});

          return;
        }

        // A password must contain at least one lowercase letter
        if (!/[a-z]/.test(pwd)) {
          done({code: 'PASSWORD_HAS_NO_LOWERCASE_LETTERS'});

          return;
        }

        // A password must contain at least one uppercase letter
        if (!/[A-Z]/.test(pwd)) {
          done({code: 'PASSWORD_HAS_NO_UPPERCSE_LETTERS'});

          return;
        }

        done(null, pwd);
      },
      transformAfter: async (pwd, done) => {
        try {
          const salt = await DB.from('salt').select('value').where('type', '=', "'password'");

          // A password must be hashed after validation
          done(null, Crypto.createHash('sha1').update(pwd).update(salt).digest('hex'));
        } catch (err) {
          done({code: 'INTERNAL_ERROR'});
        }
      }
    },
    kittens: {
      type: 'number',
      minValue: 0,
      transformBefore: (count, done) => {
        // A value may be passed as a string, and it will be converted to number before any validation
        done(null, Number(count));
      }
    }
  }
});

let user1 = {
  nickname: 'Vasia',
  password: 'pwd123PWD',
  kittens: 1
};

let user2 = {
  nickname: 'Petia)))',
  password: 'pwd321PWD',
  kittens: 0
};

let user3 = {
  nickname: 'Slava',
  password: '123',
  kittens: '0'
};

let user4 = {
  nickname: 'Slava',
  password: 123,
  kittens: '2'
};

UserValidator.validate(user1, (err, result) => {
  console.log(err, result);

  /* null, {
    nickname: 'Vasia',
    password: 'f3e4c83aa7c6a1da18f1facf63dcdf21c3f8a881'
  } */
});

UserValidator.validate(user2, (err, result) => {
  console.log(err, result);

  /* {
    code: 'INVALID_STRING',
    data: 'Petia)))',
    path: ['nickname'],
    info: {}
  } */
});

UserValidator.validate(user3, (err, result) => {
  console.log(err, result);

  /* {
    code: 'PASSWORD_HAS_NO_LOWERCASE_LETTERS',
    data: '123',
    path: ['password'],
    info: {}
  } */
});

UserValidator.validate(user4, (err, result) => {
  console.log(err, result);

  /* {
    code: 'TYPE_MISMATCH',
    data: 123,
    path: ['password'],
    info: {
      expectedType: 'string'
    }
  } */
});

API

createValidator(template, {customTypes = [], maxDelayNsecs = 1000000} = {})

Creates a validator. Accepts validation template, an object in the following form:

{
  type: <type>,
  missingStartegy: [MissingStrategy], // optional
  extraStrategy: [ExtraStrategy], // optional
  defaultValue: [default_value], // optional, only required if missingStartegy is MissingStrategy.Default
  values: Array|Set, // optional, an array or set of values allowed, only valid for types 'string', 'boolean', 'number'
  validateBefore: (data, done, options) => {}, // optional, a custom validation function called before other validators
  validateAfter: (data, done, options) => {}, // optional, a custom validation function called after other validators
  transformBefore: (data, done, options) => {}, // optional, a custom function to transform the object before validation
  transformAfter: (data, done, options) => {}, // optional, a custom function to transform the object after validation
  // ...fields specific for the <type>
}

validateBefore validates data after checking the type, but before any default validators. validateAfter validates data after default validators, just before transformAfter.

Example:

{
  type: 'string',
  regexp: /\d+/,
  transformAfter: (value, done) => done(null, Number(value))
}

validate(data, done, {context = {}, maxDelayNsecs = validatorMaxDelayMsecs} = {})

Performs validation.

• data -- data to be validated
• done -- callback function called after validation with either (null, newData) or (error)

Possible options are:

• context -- a context passed to custom validation functions (empty array by default)
• maxDelayNsecs -- if validation takes longer than this value (in nanoseconds), next portion of validation will be delayed until next event loop iteration if possible

ValidatorErrorCode

Constant containing the error codes:

{
    BooleanNotInValues: 'BOOLEAN_NOT_IN_VALUES',
    CustomError: 'CUSTOM_ERROR',
    ExtraFields: 'EXTRA_FIELDS',
    InvalidArrayLength: 'INVALID_ARRAY_LENGTH',
    InvalidNumber: 'INVALID_NUMBER',
    InvalidString: 'INVALID_STRING',
    InvalidStringLength: 'INVALID_STRING_LENGTH',
    MissingField: 'MISSING_FIELD',
    NumberNotInteger: 'NUMBER_NOT_INTEGER',
    NumberNotInValues: 'NUMBER_NOT_IN_VALUES',
    NoMatchingVariant: 'NO_MATCHING_VARIANT',
    StringNotInValues: 'STRING_NOT_IN_VALUES',
    TypeMismatch: 'TYPE_MISMATCH',
    UnallowedNull: 'UNALLOWED_NULL'
}

Types

There are several builtin types.

object

A JavaScript object.

Example:

{
  type: 'object',
  fields: {
    // nested fields
  }
}

array

A JavaScript array.

Example:

{
  type: 'array',
  element: {
    // element definition
  }
}

string

A string.

Example:

{
  type: 'string',
  minLength: [M], // optional, minimum string length
  maxLength: [N], // optional, maximum string length
  length: [K], // optional, exact string length
  regexp: [R] // optional, a regular expression to match the string against
}

number

A number.

Example:

{
  type: 'number',
  minValue: [M], // optional, minimum value
  maxValue: [N], // optional, maximum value
  isInteger: [true|false] // optional, specifies if number must be an integer
}

boolean

A boolean.

Example:

{
  type: 'boolean'
}

variant

Used to validate against multiple templates. The result of first successful validation is used.

Example:

{
  type: 'variant',
  variants: [{
    type: 'string',
    regexp: /\d+/,
    transformAfter: (data, done) => done(null, Number(value))
  }, {
    type: 'number'
  }]
}

If hint function is provided to template variants, raw data is checked against that function. Templates with hint returning false-ish values are excluded from validation. Templates are used in the same order they are specified. This may be used to optimize large template validation. Example:

[{
  type: 'object',
  hint: (rawValue, done) => done(rawValue.kind === 'KIND_A'),
  fields: {
    kind: {
      type: 'string',
      values: ['KIND_A']
    }
    // Dozens of fields for kind A
  }
}, {
  type: 'object',
  hint: (rawValue, done) => done(rawValue.kind === 'KIND_B'),
  fields: {
    kind: {
      type: 'string',
      values: ['KIND_B']
    }
    // Dozens of fields for kind B, different from the ones for kind A
  }
}]

If no variant matches the data, a NoMatchingVariant error occurs.

Advanced

isNullable

Any type can be allowed to be null.

Example:

{
  type: 'string',
  isNullable: true
}

Object prototype (class) as "type"

Example:

class CustomClass {
  constructor() {
    //
  }
}

{
  type: CustomClass
}

customTypes may be used to validate instances of a class and preserve them as is. If no validator is specified, 'object' validator is used by default. This leads to loss of some properties (like instance methods) as objects are mapped (no reference equality of input and output data).