Validations

Presence

presence (boolean) - Validates that the specified value is not empty.

const value = ''
const validations = { presence: true }
const result = validate(value, validations)
/* {
    value: '',
    errors: [{ cantBeEmpty: true }]
} */

Allow Null

allowNull (boolean) - Validates that the specified value is not null or undefined.

const value = null
const validations = { allowNull: false }
const result = validate(value, validations)
/* {
    value: null,
    errors: [{ cantBeNull: true }]
} */

Null Values

The type, length, numericality, format and datetime validators won't validate a value if it's null or undefined.

To ensure your value is not null, use allowNull: false or presence: true.

Presence vs allowNull

	presence: true	allowNull: false
'Text'	Valid	Valid
123	Valid	Valid
0	Valid	Valid
' '		Valid
''		Valid
[]		Valid
{}		Valid
null
undefined

Contains

contains - The contains validator is useful for validating allowance or restriction in certain values. It checks that the given value exists in the target given by the allowed or notAllowed option.

You can specify the validator as a list, string or as an object (in which case the keys of the object are used).

allowed option examples:

const value = 'xlarge'
const validations = { contains: { allowed: ["small", "medium", "large"] } }
const result = validate(value, validations)
/* {
    value: 'xlarge',
    errors: [{ notContains: ["small", "medium", "large"] }]
} */

const value = 'hello'
const validations = { contains: { allowed: "lorem ipsum dolor" } }
const result = validate(value, validations)
/* {
    value: 'hello',
    errors: [{ notContains: "lorem ipsum dolor" }]
} */


const attr = 'price'
const validations = { contains: { allowed: {type:"Fiat", model:"500", color:"white"} } }
const result = validate(attr, validations)
/* {
    value: 'price',
     errors: [{ notContains: {type:"Fiat", model:"500", color:"white"} }]
} */

notAllowed option examples:

const value = 'small'
const validations = { contains: { notAllowed: ["small", "medium", "large"] } }
const result = validate(value, validations)
/* {
    value: 'small',
    errors: [{ contains: ["small", "medium", "large"] }]
} */


const value = 'hello'
const validations = { contains: { notAllowed: "hello world" } }
const result = validate(value, validations)
/* {
    value: 'hello',
    errors: [{ contains: "hello world" }]
} */


const attr = 'type'
const validations = { contains: { notAllowed: {type:"Fiat", model:"500", color:"white"} } }
const result = validate(attr, validations)
/* {
     value: 'type',
     errors: [{ contains: {type:"Fiat", model:"500", color:"white"} }]
} */

using both options examples:

const value = 'regular'
const validations = { contains: { notAllowed: ["xlarge", "xxlarge", "tiny"], allowed: ["small", "medium", "large"] } }
const result = validate(value, validations)
/* {
    value: 'regular',
    errors: [{ notContains: ["small", "medium", "large"] }]
} */

const value = 'xlarge'
const validations = { contains: { notAllowed: ["xlarge", "xxlarge", "tiny"], allowed: ["small", "medium", "large"] } }
const result = validate(value, validations)
/* {
    value: 'xlarge',
    errors: [
             { notContains: ["small", "medium", "large"] },
             { contains: ["xlarge", "xxlarge", "tiny"] }
            ]
} */

Length

Validates the length of the value.

It is possible to specify length constraints in different ways:

minimum (number) - The value cannot have less than the specified length

maximum (number) - The value cannot have more than the specified length

is (number) - The value length must be equal to the given length

const value = 'john'
const validations = { length: { minimum: 5, maximum: 3, is: 1 } }
const result = validate(value, validations)
/* {
    value: 'john',
    errors: [
        { isTooShort: 5 },
        { isTooLong: 3 },
        { wrongLength: 1 }
    ]
} */

Numericality

Validates constraints to acceptable numeric values.

It must be a valid Number JS object. Use { type: Number } to validate if the value is a valid JS Number object.

equalTo (number) - Specifies the value must be equal to the supplied value.

greaterThan (number) - Specifies the value must be greater than the supplied value.

greaterThanOrEqualTo (number) - Specifies the value must be greater than or equal to the supplied value.

lessThan (number) - Specifies the value must be less than the supplied value.

lessThanOrEqualTo (number) - Specifies the value must be less than or equal to the supplied value.

onlyInteger (boolean) - To specify that only integral numbers are allowed.

const value = 123.4
const validations = {
    numericality: {
        equalTo: 123,
        greaterThan: 200,
        greaterThanOrEqualTo: 123,
        lessThan: 0,
        lessThanOrEqualTo: 123,
        onlyInteger: true
    }
}
const result = validate(value, validations)
/* {
    value: 123.4,
    errors: [
        { notEqualTo: 123 },
        { notGreaterThan: 200 },
        { notLessThan: 0 },
        { notLessThanOrEqualTo: 123 },
        { notAnInteger: true }
    ]
} */

Datetime

Validates constraints to acceptable date and time values.

It must be a valid Date time JS object. Use { type: Date } to validate if the value is a valid JS Date object.

before (date) - A date must be before this value to be valid

after (date) - A date must be after this value to be valid

isAt (date) - A date must be equal to value to be valid

const value = new Date('2001-01-02')
const validations = {
    datetime : {
            before: new Date('2001-01-01'),
            after: new Date('2001-01-03'),
            isAt: new Date('2001-02-02')
        }
}
const result = validate(value, validations)
/* {
    value: '2001-01-02T00:00:00.000Z',
    errors: [
        { tooLate: '2001-01-01T00:00:00.000Z' },
        { tooEarly: '2001-01-03T00:00:00.000Z') },
        { notAt: '2001-02-02T00:00:00.000Z') }
    ]
} */

E-mail

The email validator attempts to make sure the input is a valid email. Validating emails is tricky business due to the complex rules of email address formatting.

For example john.doe@gmail is a perfectly valid email but it's most likely just the case that John has forgotten to write .com at the end.

const value = 'just\"not\"[email protected]'
const validations = { email: true }
const result = validate(value, validations)
/* {
    value: 'just\"not\"[email protected]'
    errors: [{ invalidEmail: true }]
} */

Format

format (regex) -The format validator will validate a value against a regular expression of your chosing.

const pattern = /^[0-9]{8}$/ // or you can use new RegExp('^[0-9]{8}$')
const value = '05547-022'
const validations = { format: pattern }
const result = validate(value, validations)
/* {
    value: '05547-022',
    errors: [{ invalidFormat: true }]
} */

Type

Type validator ensures a value is of the correct JavaScript type or a custom type.

type - A valid native JavaScript type, a custom type or a array with type

Native JavaScript types:

Number - double-precision 64-bit binary format IEEE 754 value

String - a UTF‐16 character sequence

Boolean - true or false

Date - represents a single moment in time in a platform-independent format.

Object - the Object class represents one of JavaScript's data types.

Array - the Array class is a object that is used in the construction of arrays.

const value = '2001'
const validations = { type: Date }
const result = validate(value, validations)
/* {
    value: '2001',
    errors:[{ wrongType: 'Date' }]
} */

Custom types:

class User { ... }

const value = 'Admin'
const validations = { type: User }
const result = validate(value, validations)
/* {
    value: 'Admin',
    errors:[{ wrongType: 'User' }]
} */

Lists - Array with types:

It is possible to validate the type of elements of an array. Just use [type].

const value = ['2']
const validations = { type: [Number] }
const result = validate(value, validations)
/* {
    value: ['2'],
    errors:[{ wrongType: ['Number'] }]
} */

Javascript Identifier

The javascript identifier validator ensures that the input is a valid javascript identifier. Javascript identifiers validator rules can be found here.

const value = "1GetTest"
const validations = { javascriptIdentifier: true }
const result = validate(value, validations)
/* {
    value: '1GetTest',
    errors: [{ invalidJavascriptIdentifier: true }]
} */

URL

The URL validator ensures that the input is a valid URL. Validating URLs are pretty tricky but this validator is inspired on a gist that can be found here.

The following options are supported:

schemes - (array of string) A list of schemes to allow. If you want to support any scheme you can use a regexp here (for example [".+"]). The default value is ["http", "https"].

allowLocal (boolean) - A boolean that if true allows local hostnames such as 10.0.1.1 or localhost. The default is false.

allowDataUrl (boolean) - A boolean that if true allows data URLs as defined in RFC 2397. The default is false

const value = "google.com"
const validations = { url: true }
const result = validate(value, validations)
/* {
    value: 'google.com',
    errors: [{ invalidURL: true }]
} */

const value = "http://localhost"
const validations = { url: {allowLocal: true} }
const result = validate(value, validations)
/* {
    value: 'http://localhost',
    errors: []
} */

const options = {schemes: ['ftp']}
const value = "ftp://google.com"
const validations = { url: options }
const result = validate(value, validations)
/* {
    value: 'ftp://google.com',
    errors: []
} */

Custom functions

Execute custom functions to specific validations cases

propName (string) - Name of the validation rule returned on error - this is optional, see below example of usage

validation (function: boolean) - Function that will be called with value argument this is optional, see below example of usage

const cardNumber = "123467890123456"
// Single function validation with valid value
const validations = { custom: { invalidCardNumber: (value) => value.length === 16 } }
const result = validate(cardNumber, validations);
/* {
    value: '123467890123456',
    errors: []
} */
//

const cardNumber = "1234"

// Single function validation with invalid value
const validations = { custom: { invalidCardNumber: (value) => value.length === 16 } }
const result = validate(cardNumber, validations);
/* {
    value: '1234',
    errors: [{ "invalidCardNumber": true }]
} */
//

// Multiple functions validation with invalid value
const validations = {
    custom: {
        invalidCardNumber: (value) => value.length === 16,
        invalidDigit: (value) => value[0] !== "2",
    },
}
const result = validate(cardNumber, validations)
/* {
    value: '1234',
    errors: [
        {  "invalidCardNumber": true },
        {  "invalidDigit": true },
    }]
} */
//


// Multiple functions validation with parcial valid values
const cardNumber = "12345678910111213"

const validations = {
    custom: {
        invalidCardNumber: (value) => value.length === 16,
        invalidDigit: (value) => value[0] !== "2",
    },
}
const result = validate(cardNumber, validations)
/* {
    value: '12345678910111213',
    errors: [
        {  "invalidDigit": true },
    }]
} */
//

You can also extract validation for variables, if you want to make your code more reusable and customizable

// Single Validation with custom propName

const cardNumber = "1234"

const propName = "invalidCardNumber";
const validation = (value) => value.length === 16
const validations = {
    custom: { [propName]: validation }, }

const result = validate(cardNumber, validations);
/* {
    value: '1234',
    errors: [{ "invalidCardNumber": true }]
} */
//