param-parser

A service that can validate, parse and format parameters for you by just calling one function.

Installation

Install package from npm.

$ npm install param-parser --save

Usage

• param-parser module provides parse() function to validate, parse and format parameter
• parse() function expects these arguments
  • param {object}: parameters to be parsed
  • specs {object[]}: array of spec (see specs section below)
  • defaultValue {object}: default value for some parameters
• parse() function return parsed parameters {object}

Example

const parser = require('param-parser')

// define specs
const specs = {
    mobile_no: [
        'required' /* required field */,
        /^\d{10}$/ /* regex */
    ],
    gender: [
        'required' /* required field */, 
        /^(M|F|m|f)$/ /* regex */, 
        String.prototype.toLowerCase /* format function */
    ],
    language: [] /* no 'required' means optional field */,
    amount: [
      parseFloat /* format function */
    ]
}

// input parameters
const input = {
    mobile_no: '1234567890',
    gender: 'M'
}

// define default value here
const defaultValue = { 
  language: 'EN' /* if no lanauge, set to 'EN' as a default value */,
  amount: 0 /* if no amount, set to 0 as a default value */
}

const param = parser.parse(input, specs, defaultValue) // parse input

/** will print
  * {
  *     mobile_no: '1234567890',
  *     gender: 'm', // format to lower case
  *     lanauge: 'EN',
  *     amount: 0
  * }
  */
console.log(param)

specs

A specs is an array of each spec.

• to define 'required' field, add required to spec, e.g.,

const specs = {
    mobile_no: [ 'required' ] /* required field */,
    gender: [] /* optional field */
}

• regex is supported to validate each parameter, e.g.,

const specs = {
    mobile_no: [ 'required',  /^\d{10}$/ ] /* validate with regex */,
    gender: [ /^(M|F|m|f)$/ ] /* validate with regex */,
    language: [] /* validate without regex */
}

• support native format function, e.g.,

const specs = {
    gender: [ 'required', /^(M|F|m|f)$/, String.prototype.toLowerCase ] /* format value to lower case */,
    language: [ String.prototype.toUpperCase ] /* format value to upper case */,
    amount: [ parseFloat ] /* format value to float */,
    name: [ 'required', String.prototype.toLowerCase, String.prototype.trim ] /* format toLowerCase and then trim */
}

• support custom format function, e.g.,

function formatMoney(num) {
    return `${num} dollar`
}

const specs = {
    amount: [ formatMoney ] /* format using formatMoney function */
}

• parameter that is not in the specs will be removed, e.g.,

// define specs
const specs = {
    mobile_no: [ 'required', /^\d{10}$/ ],
    gender: [ 'required' ],
    language: [],
}

// input parameters
const input = {
    mobile_no: '1234567890',
    gender: 'M',
    lanauge: 'EN',
    dummy1: 'dummy1',
    dummy2: 'dummy2'
}

const param = parser.parse(input, specs) // parse input

/** will print
  * {
  *     mobile_no: '1234567890',
  *     gender: 'M',
  *     lanauge: 'EN'
  * }
  * 
  * note that dummy1 and dummy2 are removed
  * because they are not defined in specs
  */
console.log(param)

• support array parameter, e.g.,

const regex = /^(YES|NO)$/
const regexpItems = new parser.RegExpItems(regex)
const specs = {
    status: [ 'required' ],
    result: [ 'required', regexpItems ]
}
const input = {
    status: true,
    result: ['YES', 'YES', 'NO']
}

const param = parser.parse(input, specs)

/** will print
  * {
  *   status: true,
  *   result: ['YES', 'YES', 'NO']
  *  }
  */

License

MIT