cerealizr

A simple library to transform objects.

Installation

$ npm i cerealizr # or yarn add cerealizr

What is it good for?

Cerealizr provides a Serializer class which allows you to transform objects into whatever you want. It's specially useful for transforming API requests or responses into nicely formatted and useful data to use in your app.

Basic Usage

const Serializer = require('cerealizr');

const someObject = {
  id: 1,
  first_name: 'John',
  country_id: 200,
  nicknames: ['johny', 'dude'],
  unmapped_key: 'no mapping'
};

const serializer = new Serializer({
  descriptor: {
    id: 'id',
    first_name: 'firstName',
    nicknames: 'nicknames',
    country_id: (key, value) => ({ [`${key}_number`]: value + 100 })
  },
  mapAllValues: false
});

serializer.serialize(someObject);
/*
Result:
{
  id: 1,
  firstName: 'John',
  country_id_number: 300,
  nicknames: ['johny', 'dude']
}
*/

Classes and functions

Serializer

Serializer accepts an object with the following parameters:

Parameter	Type	Description	Default Value
descriptor	Object	Defines how map your objects. Keys should match with the ones the original object has, and values can be strings (to map keys) or functions (to map keys and/or values).	-
mapAllValues	Boolean	Defines if keys missing in the descriptor will be mapped.	false
defaultTransform	Function (a, b) => Object	How to transform those keys that weren't defined in the descriptor. The object that returns MUST have only one key. Only works if mapAllValues is set to true.	(key, value) => ({ [key]: value })

CamelcaseSerializer && SnakecaseSerializer

This are special serializers. This serializers map the all the keys as camelcase/snakecase. This can be overridden with the descriptor. The reason this classes are provided, is because it's a usual use case to map an object from and to JSON.

For the time being, they only receive a descriptor parameter and it always maps all values. Also, the function used as values in the descriptor can only map values, as the key tranform is already defined:

const { CamelcaseSerializer } = require('cerealizr');

const someObject = {
  id: 1,
  first_name: 'John',
  country_id: 200,
  nicknames: ['johny', 'dude'],
  unmapped_key: 'no mapping'
};

const serializer = new CamelcaseSerializer({
  descriptor: {
    country_id: (value) => value + 100
  }
});

serializer.serialize(someObject);
/*
Result:
{
  id: 1,
  firstName: 'John',
  countryId: 300,
  nicknames: ['johny', 'dude'],
  unmappedKey: 'no mapping'
}
*/

Useful functions

setValue

Allows to pass a hardcoded value to a descriptor:

const descriptor = { id: 'ID', some_key: setValue(1000) }

setCamelcaseKey && setSnakecaseKey

Maps the key to camelcase/snakecase and receives a function (which defaults to value => value) to map the value:

const descriptor = { id: 'ID', some_key: setCamelcaseKey(value => value + 100) }

Custom Serializers

You can define your own serializers! Both CamelcaseSerializer and SnakecaseSerializer extend KeySerializer, which in turn extends Serializer defining a function to map the key. You can extend KeySerializer to define how to map keys, just as those serializers do.

If you want even more custom behaviour, you can even extend Serializer and override its methods.

Licence

MIT License

Copyright (c) 2021 damfinkel

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.