API.md

API

spected(rules, input)

Validates data input against a set of validation rules and returns a result object containing error information for every provided data field. Also works with deep nested objects. spected is curried.

Arguments

1. rules (Object): An object of rules, consisting of arrays containing predicate function / error message tuple, f.e. {name: [[a => a.length > 2, 'Minimum length 3.']]}. The error message can also be a function with this signature: (value, key) => message

2. input (Object|Function): The data to be validated.

Depending on the status of the input either a true or a list of error messages is returned.

Returns

(Object): An object containing the validation result.

{
    name: true,
    random: [
        'Minimum Random length of 8 is required.',
        'Random should contain at least one uppercase letter.'
    ]
}

Example

import spected from 'spected'

const capitalLetterMsg = (value, key) => `The field ${key} should contain at least one uppercase letter. '${value}' is missing an uppercase letter.`

const spec = {
  name: [
    [isNotEmpty, 'Name should not be  empty.']
  ],
  random: [
    [isLengthGreaterThan(7), 'Minimum Random length of 8 is required.'],
    [hasCapitalLetter, capitalLetterMsg],
  ]
}

const input = {name: 'foobar', random: 'r'}

spected(spec, input)

//  {
//      name: true,
//      random: [
//          'Minimum Random length of 8 is required.',
//          'The field random should contain at least one uppercase letter. 'r' is missing an uppercase letter.'
//      ]
//  }

validate(successFn, errorFn, rules, input)

Validates data input against a set of validation rules and returns a result object containing error information for every provided data field. Additionally requires success and failure callback to transform the results as needed. Also works with deep nested objects. validate is curried and is internally used by spected with a default success function () => true and a default failure function errors => errors.

Arguments

1. successFn (Function): Transform the result as needed, transformer is called when an input is valid. The result is passed to the callback enabling to return the original input value if needed.

const successFn = () => true
{name: true, random: ['error...']}

const successFn = val => val
{name: 'original value', random: ['error...']}

2. failFn (Function): Transform the result as needed, transformer is called when an input is invalid. Recieves an array of error messages.

const failFn = (errorMsgs) => head(errorMsgs)
// {name: true, random: 'something is missing'}


const failFn = (errorMsgs) => errorMsgs
// {name: true, random: ['something is missing', 'some other error...']}

3. rules (Object): An object of rules, consisting of arrays containing predicate function / error message tuple, f.e. {name: [[a => a.length > 2, 'Minimum length 3.']]}

4. input (Object|Function): The data to be validated.

Returns

(Object): An object containing the validation result.

{
    name: true,
    random: [
        'Minimum Random length of 8 is required.',
        'Random should contain at least one uppercase letter.'
    ]
}

Example

import {validate} from 'spected'
const verify = validate(
    () => true, // always return true
    head // return first error message head = x => x[0]   
)
const spec = {
  name: [
    [isNotEmpty, 'Name should not be  empty.']
  ],
  random: [
    [isLengthGreaterThan(7), 'Minimum Random length of 8 is required.'],
    [hasCapitalLetter, 'Random should contain at least one uppercase letter.'],
  ]
}

const input = {name: 'foobar', random: 'r'}

verify(spec, input)

//  {
//      name: true,
//      random: 'Minimum Random length of 8 is required.',
//  }

Spected also accepts a function as an input, to simulate if an input would contain errors if empty.

const verify = validate(a => a, a => a)
const validationRules = {
  name: nameValidationRule,
}
const input = {name: 'foobarbaz'}
const result = verify(validationRules, key => key ? ({...input, [key]: ''}) : input)
deepEqual({name: ['Name should not be empty.']}, result)