mapargs
v2.0.0
Published
map function parameters to named options with optional validation
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Readme
mapargs
map function parameters to types
installation
$ npm install mapargs
usage
Stop manually writing mapping and validation logic. Stop it right now. It's brittle and not fun.
var mapArgs = require('mapargs')
var listDocuments = mapArgs(function (authorId, skip, limit) {
// do stuff
}, {
authorId: Number,
skip: {$map: Number, $optional: true, $default: 0},
limit: {$map: Number, $optional: true, $default: 100}
})
This returns a function which we can call either with positional arguments (like the original), or named arguments by passing in an object with property names matching the parameter names.
listDocuments({name: 'f43', skip: '100'})
// equivalent to calling the original function with
// fn(43, 100, 100)
Use this when wiring up user input to application logic. Separate your gnarly HttpRequest objects from your core domain functions. Automatically map objects to their constructors.
api
mapArgs(fn: Function, mapObj?: Object) => Function
Returns a function which accepts named arguments and (optionally) has validation and defaults specified in mapObj
var add3 = function (a, b, c) {
return a + b + c
}
var named = mapArgs(add3)
named({a: 1, b: 2, c: 3})
// => 6
mapObj
should have property names corresponding to fn
's parameter names.
The values should be either mapping functions to be applied to the matching argument or an options
object.
mapArgs.validate(mapObj: Object) => Function
Returns a function which will apply all of the validation and default logic and return an arguments object or throw an error.
options
$map: Function
A mapping function to be applied to the matching argument
$default: Value
A value used when the argument is not supplied or is undefined
$valid: Predicate Function
A function returning true
if the argument is valid, false
otherwise. mapArgs
will throw an Error
if the validation fails. Validation is run after the mapping function is applied.
$optional: Boolean
If true
, the parameter is optional. If a default is specified, it will be used if the argument is undefined. If there is no default specified and the parameter is not marked optional, an error will be thrown.
a note about booleans
We treat the built-in Boolean
constructor liberally. Unlike native Boolean
, not all non-empty strings evaluate to true. Instead, only strings which case-insensitively compare to t
, true
, y
, or yes
are true; otherwise they're false. And only numbers > 0 evaluate to true; otherwise they're false.
running the tests
change to package root directory
$ npm install
$ npm test
contributors
jden [email protected]
license
ISC. (c) 2015 AgileMD, Inc [email protected]. See LICENSE.md