csh-file-formatter-module

Wrapper around json-map-transformer to map JSON objects using common transformations.

Installation

npm i csh-file-formatter-module

Usage

const { JSONTransformer } = require('csh-file-formatter-module');
 
const formater = new JSONTransformer(template, staticKeys, configOptions);
 
console.log(formater.transform(obj, afterTransform))

Template

key: Property name on the output object

path: Property in the input object that will be mapped. Can also be an array of possible paths. Can be omitted if the key will be the same.

transform: Function that receives input value/Name of a predefined transformation function. Can be an array of mixed values.

default: Value to set if the transformed value is undefined. Can also be a function that will be executed when the JSONTransformer is created.

After transformation, undefined and empty strings are omitted.

Example:

{
    timestamp: {
        path: 'updatedAt',
        transform: 'LOCALE_STRING'
    },
    name: 'author', // same as { path: 'author', omit: ['', undefined] },
    id: {
        transform: (id) => id + '123'
    },
    description: {
        transform: ['NORMALIZE', (description) => description.replace('a', 'e')] // normalize(description).replace(...)
    }
}

Transformations

The following transformations are predefined:

name	description
Strings
NORMALIZE_ALL	Replace : with _ and spaces with -
NORMALIZE	Replace spaces with -
UPPERCASE	Converts string to uppercase
LOWERCASE	Converts string to lowercase∫
MAX_CHARS	Returns substring(0, maxChars)
TAGS_NORM	Removes tags from string
SPACES_NORM	Removes \\n and \\r characters with single space. Also removes multiple spaces with single one
HTML_NORM	Replaces HTML entities to proper char, removes unicode and special chars
URLs
URL_ORIGIN	Returns origin from an url
URL_PATH	Returns path from an url
Dates
LOCALE_STRING	Transform string date to locale string date (within timezone specified)
YEAR_MONTH	Gets YYYYMM format from a ISO string date
ISO_STRING	Returns ISO string from a date
SPLIT_TIMESTAMP	Given a ISO date or UNIX timestamp, returns an array with date components

Static Keys

Object with values to add to the output object. Each key must be a value or function. In case of functions, they are evaluated each time transform is executed.

Example:

{
    origin: 'a value',
    number: () => 5 
}

Config options

There are possible variables to configure:

• maxChars. Sets the value for MAX_CHARS transformation. Defaults to 260000.
• timezone. Time zone used for LOCALE_STRING transformation.
• keepUnused. Boolean to indicate the unused fields from original object should be kept. The fields unused are stored on unusedFieldsKey key and are transformed with JSON.stringify (see stringifyUnused). Defaults to false.
• unusedFieldsKey. Name of the key where the unused fields are stored. Defaults to meta. If the value passed is . the unused keys will be added in the output object.
• stringifyUnused. Indicates if the unused fields should be stringified or not. Defaults to true.
• afterTransform. Function that will receive the output object and process it. Can be overrided on the transform method. Defaults to: x => x.

.transform(obj, afterTransform)

Params

obj: Object to be transformed

afterTransform: Function to be used on the transformation. Defaults to configOptions.afterTransform

Example:

myTransformer.transform(obj, (outputObj, inputObject) => {
    outputObj.processed = 1 + inputObject.count;
    return outputObj;
})

Example

const { JSONTransformer } = require('csh-file-formatter-module');
 
const template = {
    slug: {
        transform: ['NORMALIZE', 'UPPERCASE']
    },
    description: 'details',
    url: {
        path: 'source.url',
        transform: 'URL_ORIGIN'
    },
    author: {
        transform: author => 'By ' + author
    },
    date: {
        path: 'created_at',
        transform: 'LOCALE_STRING'
    }
};
 
const staticKeys = {
    source: 'json-map-transform',
    id: () => {
        return 'addd';
    }
}
 
const configOpts = {
    keepUnused: true,
    timezone: 'America/Bogota'
}
 
function afterTransform(outputObj) {
    outputObj.identifier = `${outputObj.slug}-${outputObj.id}`;
    return outputObj;
}
 
const formater = new JSONTransformer(template, staticKeys, configOpts);
const output = formater.transform({
    slug: 'a new challenge',
    details: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Pellentesque tempor.',
    source: {
        url: 'https://es.lipsum.com/feed/html',
        provider: 'lipsum'
    },
    author: 'sit amet',
    location: 'Spain',
    created_at: '2019-05-03T11:15:43Z'
}, afterTransform);
 
// output = 
// {
//   slug: 'A-NEW-CHALLENGE',
//   description: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Pellentesque tempor.',
//   url: 'https://es.lipsum.com',
//   author: 'By sit amet',
//   date: '05/03/2019, 06:15:43',
//   meta: '{"source":{"url":"https://es.lipsum.com/feed/html","provider":"lipsum"},"location":"Spain"}',
//   source: 'json-map-transform',
//   id: 'cc612cda-1535-4221-b7f8-f86259689562'
//   identifier: 'A-NEW-CHALLENGE-cc612cda-1535-4221-b7f8-f86259689562'
// }