JS create a new array of objects with new key

Question

So I have two array of JSON objects, rooms, and reservations. I want to output a new array of objects that has data combined from both those arrays with a new data type. Not sure how to create that new data type.

var rooms = [
     {id:1, room:'treehouse'},
     {id:2, room:'casa'},
     {id:3, room:'vacation'},
     {id:4, room:'presidential'}
];

var reservations = [
  {id:1, roomID:'2', time:'2pm', location:'rome'},
  {id:2, roomID:'3', time:'4pm', location:'paris'},
  {id:3, roomID:'1', time:'4pm', location:'london'},
  {id:4, roomID:'2', time:'7pm', location:'rome'},
  {id:5, roomID:'1', time:'12pm', location:'london'},
  {id:6, roomID:'4', time:'4pm', location:'berlin'}
];

Desired Output:

var bookings = [
  {id: 1, roomid:1, time:'12pm',location:'london', roomname:'treehouse'},
  {id: 2, roomid:1, time:'4pm', location:'london', roomname:'treehouse'},
  {id: 3, roomid:2, time:'2pm', location:'rome', roomname:'casa'},
  {id: 4, roomid:2, time:'7pm', location:'rome', roomname:'casa'},
  {id: 5, roomid:3, time:'4pm', location:'paris', roomname:'vacation'},
  {id: 6, roomid:4, time:'4pm', location:'berlin', roomname:'presidential'}
]

I am confused on the logic on how to do this. I was thinking of iterating over the reservations array and for each reservation grab roomId and check in a map structure of rooms and then output. I'm not quite sure what to do.

is it intended roomid vs roomID? and why is the type different one is a number, one is a string. — Nina Scholz
– Nina Scholz, Commented Sep 25, 2018 at 17:13

Luis felipe De jesus Munoz · Accepted Answer · 2018-09-25 17:13:29Z

1

var rooms = [
     {id:1, room:'treehouse'},
     {id:2, room:'casa'},
     {id:3, room:'vacation'},
     {id:4, room:'presidential'}
];

var reservations = [
  {id:1, roomID:'2', time:'2pm', location:'rome'},
  {id:2, roomID:'3', time:'4pm', location:'paris'},
  {id:3, roomID:'1', time:'4pm', location:'london'},
  {id:4, roomID:'2', time:'7pm', location:'rome'},
  {id:5, roomID:'1', time:'12pm', location:'london'},
  {id:6, roomID:'4', time:'4pm', location:'berlin'}
];

console.log(
  reservations.map(a=>({...a, roomname: rooms.find(b=>b.id==a.roomID).room}))
)

answered Sep 25, 2018 at 17:13

Luis felipe De jesus Munoz

8,0133 gold badges38 silver badges54 bronze badges

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

Comments

Nina Scholz · Accepted Answer · 2018-09-25 17:21:31Z

You could tale the power of a Map and get the additional information for a new object.

var rooms = [{ id: 1, room: 'treehouse' }, { id: 2, room: 'casa' }, { id: 3, room: 'vacation' }, { id: 4, room: 'presidential' }],
    roomMap = new Map(rooms.map(({ id: roomid, room: roomname }) => [roomid, { roomname }])),
    reservations = [{ id: 1, roomID: '2', time: '2pm', location: 'rome' }, { id: 2, roomID: '3', time: '4pm', location: 'paris' }, { id: 3, roomID: '1', time: '4pm', location: 'london' }, { id: 4, roomID: '2', time: '7pm', location: 'rome' }, { id: 5, roomID: '1', time: '12pm', location: 'london' }, { id: 6, roomID: '4', time: '4pm', location: 'berlin' }],
    bookings = reservations.map(o => Object.assign({}, o, roomMap.get(+o.roomID)));

console.log(bookings);

.as-console-wrapper { max-height: 100% !important; top: 0; }

trk · Accepted Answer · 2018-09-25 17:25:53Z

0

You could use

reservations.map(function (val) {
    return Object.assign(val, rooms.find(function (item) {
        return val.roomID === item.id ? item : {}
    }))
})

Let me know if that works for you.

answered Sep 25, 2018 at 17:25

trk

2,23815 silver badges21 bronze badges

Comments

amrender singh · Accepted Answer · 2018-09-25 17:26:23Z

You can use Array.reduce() to create a map of id map with room name and then use Array.map() on reservations to merge the room with given id with roomname:

var rooms = [ {id:1, room:'treehouse'}, {id:2, room:'casa'}, {id:3, room:'vacation'}, {id:4, room:'presidential'} ];

var reservations = [ {id:1, roomID:'2', time:'2pm', location:'rome'}, {id:2, roomID:'3', time:'4pm', location:'paris'}, {id:3, roomID:'1', time:'4pm', location:'london'}, {id:4, roomID:'2', time:'7pm', location:'rome'}, {id:5, roomID:'1', time:'12pm', location:'london'}, {id:6, roomID:'4', time:'4pm', location:'berlin'} ];

let roomMap = rooms.reduce((a,curr)=>{
  a[curr.id] = {roomname : curr.room};
  return a;
},{});
let result = reservations.map((o)=> Object.assign({},o,roomMap[o.roomID]));
console.log(result);

Mohammed Ashfaq · Accepted Answer · 2018-09-25 17:42:26Z

0

var reservations = [
  {id:1, roomID: 2, time:'2pm', location:'rome'},
  {id:2, roomID: 3, time:'4pm', location:'paris'},
  {id:3, roomID: 1, time:'4pm', location:'london'},
  {id:4, roomID: 2, time:'7pm', location:'rome'},
  {id:5, roomID: 1, time:'12pm', location:'london'},
  {id:6, roomID: 4, time:'4pm', location:'berlin'}
];

var rooms = [
     {id:1, room:'treehouse'},
     {id:2, room:'casa'},
     {id:3, room:'vacation'},
     {id:4, room:'presidential'}
];
reservations.forEach(reservation => {
  reservation.roomname = rooms.find(({id}) => id === reservation.roomID).room;
})

console.log(reservations);

edited Sep 25, 2018 at 17:42

answered Sep 25, 2018 at 17:24

Mohammed Ashfaq

3,4262 gold badges19 silver badges24 bronze badges

Comments

Leonid Pyrlia · Accepted Answer · 2018-09-25 17:43:22Z

You can create a lookup has with Array.prototype.reduce and Array.prototype.map to iterate over the reservations array and construct the desired output:

var rooms = [{id:1, room:'treehouse'},{id:2, room:'casa'},{id:3, room:'vacation'},{id:4, room:'presidential'}];

var reservations = [{id:1, roomID:'2', time:'2pm', location:'rome'},{id:2, roomID:'3', time:'4pm', location:'paris'},{id:3, roomID:'1', time:'4pm', location:'london'},{id:4, roomID:'2', time:'7pm', location:'rome'},{id:5, roomID:'1', time:'12pm', location:'london'},{id:6, roomID:'4', time:'4pm', location:'berlin'}];

var roomHash = rooms.reduce((all, {id, room}) => ({...all, [id]: room }), {});

var result = reservations.map(item => ({...item, room: roomHash[item.roomID]}));

console.log(result);

Collectives™ on Stack Overflow

JS create a new array of objects with new key

6 Answers 6

Comments

Comments

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

6 Answers 6

Comments

Comments

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related