data-transformation-utils

JS Library representing utility allowing assigning a chain of transformations to be executed over input value.

Installation

npm i --save data-transformation-utils

Getting Started

import { Transformer, TwoWayTransformer } from 'data-transformation-utils'

const transformer = new Transformer(transformations)

Examples of usage

Transformer

default usage

const transformativeValue = {
  massProp: 1000,
  stringProp: '',
}

const transformationChain = [
  ( object ) => {
    object.massProp = object.massProp / 1000
    return object
  },
  ( object ) => {
    object.stringProp = object.stringProp === '' ? null : object.stringProp
    return object
  }
]


const transformer = new Transformer( transformationChain )

transformer.applyTransformations( transformativeValue )

Result:

{
  massProp: 1,
  stringProp: null
}

Ignore changing the data type in the transformation functions

const transformativeValue = null

const transformations = [
  ( value ) => value + '13', // always returns string
  ( value ) => {
    return {
      value
    }
  }
]

const transformer = new Transformer( transformations )

const transformedValue = transformer.applyTransformations( transformativeValue, false )

console.log( transformedValue )

Result:

{
  value: "null13"
}

TwoWayTransformer

const transformativeValue = {
  massProp: 1000,
  stringProp: '',
}

const directTransformation = [
  ( object ) => {
    object.massProp = object.massProp / 1000
    return object
  },
  ( object ) => {
    object.stringProp = object.stringProp === '' ? null : object.stringProp
    return object
  }
]

const inverseTransformation = [
  ( object ) => {
    object.massProp = object.massProp * 1000
    return object
  },
  ( object ) => {
    object.stringProp = object.stringProp === null ? '' : object.stringProp
    return object
  }
]

const transformerMods = {}
transformerMods[ TwoWayTransformer.MODS.DIRECT ] = directTransformation
transformerMods[ TwoWayTransformer.MODS.INVERSE ] = inverseTransformation


const transformer = new TwoWayTransformer( transformerMods )

const directTransformedValue = transformer.directTranform( transformativeValue )
const inverseTransformedValue = transformer.inverseTransform( directTransformedValue )

console.log( inverseTransformedValue )

Result:

{
  massProp: 1000,
  stringProp: ""
}

Class Properties

Transformation

constructor( transformationChain )

Arg	Type	Default	Description
transformationChain	array	undefined	transformation function array

applyTransformations( transformativeValue, keepTypeof )

Arg	Type	Default	Description
transformativeValue	any	undefined	Value to be transformed by the function chain
keepTypeof	boolean	true	Flag responsible for tracking the returned data type from converter functions

TwoWayTransformer

static MODS

property	Description
DIRECT	Direct transformation of data
INVERSE	Inverse transformation

The sequence of transformation functions in a chain is important

constructor( transformationMods )

Arg	Type	Default	Description
transformationMods	object	undefined	Object of transformation chains corresponding to a particular mod

Pseudocode:

transformationMods = {
        TwoWayTransformer.MODS.DIRECT: array[],
        TwoWayTransformer.MODS.INVERSE: array[]
}

directTransform( transformativeValue, keepTypeof)

Arg	Type	Default	Description
transformativeValue	any	undefined	Value to be transformed by the function chain
keepTypeof	boolean	true	Flag responsible for tracking the returned data type from converter functions

inverseTransform( transformativeValue, keepTypeof)

Arg	Type	Default	Description
transformativeValue	any	undefined	Value to be transformed by the function chain
keepTypeof	boolean	true	Flag responsible for tracking the returned data type from converter functions