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user278639 user278639 - 7 months ago 28
CoffeeScript Question

What is a succinct way to write a coffeescript function that converts my json array into the format that I want

I have this json object:

  op = [{"id":7,"d_set_id":1,"option_value_id":5,"product_id":3,"model":"1300","option_type":"Plunger Diameter","option":"5.0 inch Plunger Diameter","product":"Packing","route":"part_option_values","reqParams":null,"restangularized":true,"fromServer":true,"parentResource":{"route":"parts","parentResource":null,"id":"29"},"restangularCollection":false},{"id":9,"d_set_id":5,"option_value_id":11,"product_id":3,"model":"1300","option_type":"main drum diameter","option":"1.0  main drum diameter","product":"Packing","route":"part_option_values","reqParams":null,"restangularized":true,"fromServer":true,"parentResource":{"route":"parts","parentResource":null,"id":"29"},"restangularCollection":false}]


I wrote this function to convert it to the format that I want:

addItems: (op) ->

   variant = { 

    product_id: "undefined"

    model: "undefined"

    options: []

    product: "undefinded"

    option_value_ids: []

    quantity: 1

  }   

  op.forEach (obj,i) ->

    variant.product_id = obj.product_id

    variant.model = obj.model

    variant.options.push obj.option

    variant.product = obj.product

    variant.option_value_ids.push obj.option_value_id

  variant.options = variant.options.join(', ')

  items.push variant


It successfully changes it into my desired result.

  items = [{"product_id":3,"model":"1300","options":"5.0 inch Plunger Diameter, 1.0  main drum diameter","product":"Packing","option_value_ids":[5,11],"quantity":1},{"product_id":3,"model":"1300","options":"5.0 inch Plunger Diameter, 1.0  main drum diameter","product":"Packing","option_value_ids":[5,11],"quantity":1}]


... but this doesn't seem like a very succinct way to write this function. What is a better way?

Duane Duane
Answer

Yes! This can all be done succinctly with three concepts. Maps, destructuring and Object Shorthand notation (all three available in ES2015/6 as well as coffeescript)

options = []
ids = []

# We need to aggregate id's and options first
for {option_value_id, option} in op
  ids.push option_value_id
  options.push option

# Map through to the new Object
items = op.map ({ product_id, model, product}) ->
  {
    product_id
    model
    options: options
    product
    option_value_ids: ids
    quantity: 1
  }

Array.map will take an array and transform each element (in this case a subset of the bigger object) and return a new Array. We will destructure the incoming object in the arguments and then shorthand them back into an object format.

Array Map

Object Destructuring

Shorthand Notation

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