Add key/value pair to object within array of arrays?

Question

Given the following structure:

const data = {
  "show": "Family Guy",
  "characters": [
      [{name: 'Peter', age: 40, city: 'Quahog'}],
      [{name: 'Louis', age: 30}],
      [{name: 'Chris', age: 16}],
      [{name: 'Stewie', age: 1}]
    ]
 }

How can we add to each character the key/value pair of city: 'Quahog' so the output looks as follows:

const item = {
  "show": "Family Guy",
  "characters": [
      [{name: 'Peter', age: 40, city: 'Quahog'}],
      [{name: 'Louis', age: 30, city: 'Quahog'}], // city added
      [{name: 'Chris', age: 16, city: 'Quahog'}], // city added
      [{name: 'Stewie', age: 1, city: 'Quahog'}]  // city added
    ]
 }

We tried using:

let city = data.characters.[0][0].city;
costs = _.map(items, (itemArray) => {
            items = _.map(itemArray, (item) => {
              if(!item.city) {
                item.city = city;
              }
        });

But it's not working as intended and we can't get the desired output. Any idea how to accomplish this?

Toni Bardina Comas · Accepted Answer · 2022-06-06 15:54:13Z

2

Not sure about the reason for having these single item arrays but this solution will do the work (I'll recommend you take a look at the process that creates this data format which is a little weird)

const data = {
  "show": "Family Guy",
  "characters": [
      [{name: 'Peter', age: 40, city: 'Quahog'}],
      [{name: 'Louis', age: 30}],
      [{name: 'Chris', age: 16}],
      [{name: 'Stewie', age: 1}]
    ]
 }
 
 const city = data.characters.find(characters => characters.find(character => character.city))[0].city

const dataWithCities = {
 ...data,
 characters: data.characters.map(characters => characters.map(character => character.city ? character : {...character, city}))
 }
 
 console.log(dataWithCities)

answered Jun 6, 2022 at 15:54

Toni Bardina Comas

1,8081 gold badge7 silver badges18 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Carsten Massmann · Accepted Answer · 2022-06-06 17:07:49Z

1

Here is another way of doing it with .reduce():

const data = {
  "show": "Family Guy",
  "characters": [
  [{name: 'Peter', age: 40, city: 'Quahog'}],
  [{name: 'Louis', age: 30}],
  [{name: 'Chris', age: 16}],
  [{name: 'Stewie', age: 1}]
]
 };

data.characters.reduce((a,c)=>
 (c[0].city=a[0].city,a));

console.log(data);

When using .reduce() without a second argument it will pick up the first array element as the initial value which is then used as a template to copy the .city property to all the other elements. The actual return value of the .reduce() method is discarded but the input array itself (data) is modified in the process and is then shown in the console.log() expression.

edited Jun 6, 2022 at 17:07

answered Jun 6, 2022 at 15:47

Carsten Massmann

28.4k3 gold badges25 silver badges49 bronze badges

3 Comments

Big Mike Over a year ago

Thank you so much, this is the shortest and sweetest way to do it. In your desc, did you mean with a second argument? Also, in the return does the ,a part just write the modified result back to a, or does it do something else? Thanks again

Carsten Massmann Over a year ago

Well, the callback function is the first argument of the .reduce() method (the callback function in turn has two arguments). But the missing second argument to the .reduce() method would have been a starting value, which is missing on purpose here.

Carsten Massmann Over a year ago

The ,a part in the callback makes sure that the accumulator (in this case: the first array element) is handed along to the next iteration. Without it the .reduce() call would fail.

TappedAsh · Accepted Answer · 2022-06-06 15:44:54Z

0

try this one

let city = data.characters.[0][0].city;
let newdata = [];
data.characters.map(items, (itemArray) => {
        items = _.map(itemArray, (item) => {
          if(item.city === undefined) {
              newdata.push({...item , city});
          } else { 
           newdata.push({...item});
           }

    })
    costs = {...newdata}

answered Jun 6, 2022 at 15:44

TappedAsh

11 bronze badge

1 Comment

Ethan Over a year ago

Please add supporting details to your answer to improve it.

Faizal Hussain · Accepted Answer · 2022-06-06 15:45:10Z

0

You can do this without lodash

const data = {
  "show": "Family Guy",
  "characters": [
      [{name: 'Peter', age: 40, city: 'Quahog'}],
      [{name: 'Louis', age: 30}],
      [{name: 'Chris', age: 16}],
      [{name: 'Stewie', age: 1}]
    ]
 }

const chars = data.characters.map((x)=>{

    return {...x[0] , city : x[0].city ? x[0].city : city} 
})

const items = {...data , characters : chars};

answered Jun 6, 2022 at 15:45

Faizal Hussain

1,5812 gold badges12 silver badges20 bronze badges

1 Comment

Big Mike Over a year ago

hmm this doesn't wrap each character in an array, it's just a group of object

drent · Accepted Answer · 2022-06-06 17:21:08Z

0

const { city } = data.characters.find(([item]) => !!item.city?.length)[0];

const newData = {
    ...data,
    characters: data.characters.map(([char]) => [{ ...char, city }])
};

answered Jun 6, 2022 at 17:21

drent

1248 bronze badges

Collectives™ on Stack Overflow

Add key/value pair to object within array of arrays?

5 Answers 5

Comments

3 Comments

1 Comment

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

Comments

3 Comments

1 Comment

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related