property-set

Intelligently set properties on an object using a string with dot-notation.

Installation

npm i -S prop-set

Simple Example

This module was specifically written for mapping data from one source onto an object so that you can easily maintain a mapping file. However, let's take a single, simple example first.

To be clear, this is an example and doesn't represent the most efficient way to set a propery's value. I wouldn't use this module for that.

Let's take the case where you want to set a value in the userAccount object. We want to map the profile.contactInfo.phoneNumber property, we want to set it to [phone].

const propSet = require('prop-set')

let userAccount = {}

propSet(userAccount, 'profile.contactInfo.phoneNumber', '[phone]')

We passed in a blank object so the output is:

{
  "profile": {
    "contactInfo": {
      "phoneNumber": "[phone]"
    }
  }
}

Usage

Let's take the case where you have a CSV file who's columns you need to map into an object. You can either manually map these and edit your code every time, or create a config file.

csv-config-file.json

[
  { "from": "#rack", "to": "rack" },
  { "from": "rack_position_bottom", "to": "location.rackUnit" },
  { "from": "equipment", "to": "device.equipmentType" },
  { "from": "service_tag", "to": "serialNumber" },
  { "from": "service_tag", "to": "device.serialNumber" },
  { "from": "node_name", "to": "device.hostName" },
  { "from": "mac_address", "to": "device.primaryMac" },
  { "from": "instance_type", "to": "device.node" }
]

You can now import this file and iterate through the mappings, including mapping the same property to two places if necessary.

index.js

const propSet = require('prop-set'),
      csvConfig = require('./csv-config-file')

// Splits by comma, then returns the name and index for later mapping.
const mapHeader = lineOne => lineOne.split(',').map((columnName, index) => ({ name: columnName, column: index }))

const rows = [{...}, {...}, {...}],  // This represents a CSV file split by new lines
      columns = mapHeader(rows[0]),  // This assumes the first row is a header
      maxRows = rows.length          // Set the upper bounds so it doesn't need to calculate every loop.

for (let i = 1; i < maxRows; i++) {
  const columns = rows[i].split(',')
  let newRecord = {}

  csvConfig.forEach(configMap => {
    // Idenitfy which column index the data should come from.
    const thisColumnInt = csvColumns.find(i => i.name === configMap.from).column

    stringPathSet(newRecord, configMap.to, columns[thisColumnInt])
  })

  // Output the newly generated and mapped object
  console.info(newRecord)
}