Morph Morph
Isomorphic transformations. Map, transform, filter, reduce, and morph your objects
Getting Started
$ npm i --save morphmorphand then
const Mapper = require('morphmorph')
const mapper = new Mapper(/* [config] */)
const old = {
here: {
there: {
anywhere: 'Earth'
}
}
}
const mappings = [ 'here.there.anywhere:location' ]
const transformation = mapper.map(mappings, old)
// -> { location: 'Earth' }Creating Transformations
Every transformation can be represented by a mapping passed in as the first parameter
to mapper.map(). Mappings can either be of type String or Object. A mapping such as 'before:after'
is equivalent to: { field: 'before:after' }
Basic
const mappings = [
'before:after',
'egg:they.can.be.deeply.nested', // deeply nested target
'data.user.updated:updated' // deeply nested source
]
return mapper.map(mappings, obj)Functions
When creating a mapping, if you pass a function as the type parameter,
the function you passed will be called with the following properties to produce
the result:
const mapping = {
field: 'name',
type: function (value, mapping, options, sourceObj, targetObj) {
// value: the value grabbed from the source object
// mapping: this specific mapping
// options: config you specified by `new Mapper(options)`
// sourceObj: object you passed as mapper.map(mapping, sourceObj)
// targetObj: object you passed as mapper.map(m, sourceObj, targetObj). Default to `{}`
}
}Arrays
You can also pass an Array of functions and MapLib will perform a right-to-left
function composition:
const mapping = {
field: 'id:pin',
type: [
Number, // called last
v => v.substr(0, 4)
v => v.replace(/\D/g, '') // called first
]
}
mapper.map([mapping], { id: 'U1234342'}) // -> 1234Function Compositions
If you want to do function compositions the traditional way, you can use Mapper.compose(...myFilterFunctions). Again it will be a right-to-left composition.
Reductions
By specifying your field property as an array, you can reduce multiple values into a single one. The values will be included as the first parameter of your type function. The target field is specified by the last mapping in your array
Example
const response = {
user: {
firstName: 'Mike',
lastName: 'Fix',
professionInfo: {
title: 'Mr',
occupation: 'Software Engineer'
}
}
}
const mapping = {
field: [
'user.firstName',
'user.lastName',
'user.professionInfo.title',
'user.professionInfo.occupation',
'description'
],
type: ([name1, name2, title, occ]) =>
`${title}. ${name1} ${name2} is a ${occ}`
}
mapper.map([mapping], response).description // -> 'Mr. Mike Fix is a Software Engineer'Types
You can specify a type system by passing in the types option:
const types = {
number: Number,
notNullString: v => (v || '')
}
const mapper = new Mapper({ types })and then specify which type to use as a string for each mapping:
const mappings = [
{ field: 'haircolor', type: 'notNullString' },
{ field: 'daysRemaining': type: 'number' }
]
return mapper.map(mappings, hairSubscriptionResponse)Note: each function in the type specification is passed the same parameters as the normal type functions
Config
You can pass in a config object to Mapper to create your own mapping system:
Options
| Field | Type | Default |
|---|---|---|
types |
Object |
{} |
objDelimiter |
String |
"." |
mapDelimiter |
String |
":" |
preFilters |
Array |
[] |
postFilters |
Array |
[] |
Example
const mapper = new Mapper({
objDelimiter: '|',
mapDelimiter: '->',
types: { bool: Boolean },
preFilters: [ FILTER_NULL ],
postFilters: [ REMOVE_PASSWORD ]
// add other fields to your config here
})Static methods
Mapper.get
Method used to grab a deeply nested field from an object.
const get = Mapper.get('key'/*, delimiter */)
const field = get({ key: true })
// -> trueMapper.assign
Method used to apply a deeply nested field to an object.
const set = Mapper.assign('user.id'/*, delimiter */)
const targetObject = set({}, 1)
// -> { user: { id: 1 } }Mapper.compose
Method used to apply function compositions
const fun1 = v => `${v}!`
const fun2 = v => v.toUpperCase()
const fun3 = String
const exclaim = Mapper.compose(fun1, fun2, fun3)
exclaim('hey') // -> HEY!Bonus
Dependencies: None!
Size: <2KB gzipped
Examples
See /examples or test/index.spec.js for many examples of how to use MorphMorph.
Thanks
- Mostly Adequate Guide to Functional Programming for examples and reference implementations