Key value pair string generation out of an array React JS

Question

I have following array (foodDetailsList)

  [{"food_id": 5, "quantity": 100, "quantity_unit": gm}, 
  {"food_id": 45, "quantity": 200, "quantity_unit": gm}, 
  {"food_id": 22, "quantity": 300, "quantity_unit": gm}]

Out of which, I wish to create following variable String as an OUTPUT:

'food[0][food_id]': '5',
'food[0][quantity]': '100',
'food[0][quantity_unit]': 'gm',
'food[1][food_id]': '45',
'food[1][quantity]': '200',
'food[1][quantity_unit]': 'gm',
'food[2][food_id]': '45',
'food[2][quantity]': '200',
'food[2][quantity_unit]': 'gm'

I wanted to try something like following:

const createString = ()=>{
    let finalFoodList =[];
    foodDetailsList.map((food,key) =>{
              finalFoodList.push({
            'food['+[key]+'][food_id]'`:food.id,
            'food['+[key]+'][quantity]'`:food.quantity
              });
            });
    console.log("final variable is : ",finalFoodList.toString);
}

Need to improve above code syntatically so that above output is received.

Is your wanted output an object?

Nick Parsons
– Nick Parsons

2020-09-06 12:32:48 +00:00
Commented Sep 6, 2020 at 12:32 — Nick Parsons
– Nick Parsons, Commented Sep 6, 2020 at 12:32
I wish the output as a String exactly as mentioned above

Sakshi
– Sakshi

2020-09-06 12:34:05 +00:00
Commented Sep 6, 2020 at 12:34 — Sakshi
– Sakshi, Commented Sep 6, 2020 at 12:34

David Losert · Accepted Answer · 2020-09-06 14:17:31Z

1

You can use the map function to iterate over your original array, then use Object.keys to get all keys of the contained food-objects and map over those keys as well to get a generic solution like this:

const foodList = [
  {"food_id": 5, "quantity": 100, "quantity_unit": 'gm'}, 
  {"food_id": 45, "quantity": 200, "quantity_unit": 'gm'}, 
  {"food_id": 22, "quantity": 300, "quantity_unit": 'gm'}]


const foodString = foodList.map((food, index) => 
   Object.keys(food).map(key => `'food[${index}][${key}]': '${food[key]}'`).join('\n')
 ).join('\n');

console.log(foodString);

The join()-Method joins all array-members as string with linebreaks as separators.

edited Sep 6, 2020 at 14:17

answered Sep 6, 2020 at 12:51

David Losert

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2 Comments

Sakshi Over a year ago

and how to create a hashmap of it instead of string?

David Losert Over a year ago

Do you mean a Map-Object? Or what exactly is a Hash-Map for you in JavaScript? I am asking cause it is not a native type in JS.

Nick Parsons · Accepted Answer · 2020-09-06 12:41:04Z

You can use .map() on your arr of objects. For each object you can destructure it to obtain the food_id, quantity and quantity_unit properties. Based on that, you can return a string in the format which you desired, using the index i provided in the .map() callback as the index for food in your string. Once you have obtained an array of strings, you can join each string using .join('\n').

See example below:

const arr = [{"food_id": 5, "quantity": 100, "quantity_unit": 'gm'}, 
  {"food_id": 45, "quantity": 200, "quantity_unit": 'gm'}, 
  {"food_id": 22, "quantity": 300, "quantity_unit": 'gm'}];
  
  
const res = arr.map(({food_id, quantity, quantity_unit}, i) => 
  `'food[${i}][food_id]': '${food_id}'\n'food[${i}][quantity]': '${quantity}'\n'food[${i}][quantity_unit]': '${quantity_unit}'`
).join('\n');

console.log(res);

score 0 · Accepted Answer · 2020-09-06 13:23:56Z

try this:

const foodList = [
    {"food_id": 5, "quantity": 100, "quantity_unit": gm}, 
    {"food_id": 45, "quantity": 200, "quantity_unit": gm}, 
    {"food_id": 22, "quantity": 300, "quantity_unit": gm}
];

const createString = () => {
    const foodLen = foodList.length;
    let finalFoodList = foodList.map((food, index) => {
        return index !== foodLen ? (
            `'food[${index}][food_id]': '${food.food_id}',\n
            'food[${index}][quantity]': '${food.quanatity}',\n
            'food[${index}][quantity_unit]': '${food.quantity_unit}',\n`
        ) : (
             `'food[${index}][food_id]': '${food.food_id}',\n
            'food[${index}][quantity]': '${foof.quanatity}',\n
            'food[${index}][quantity_unit]': '${food.quantity_unit}'
        );
    });
}

get length of foodList array.
map function creates new array.
second parameter in map function gives current iteration number.
we use ternary operator to return conditional output.

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