Group JSON array by key value

Question

Please help to combine object keys values from json arrays by key.

    const input=[{
   "Date":"04/10/2019",
   "Time":"15:35",
   "Title":"Flight -\u00a0Group C",
   "Description":"Arrival 19:40"
},
{
   "Date":"04/10/2019",
   "Time":"Evening",
   "Title":"Welcome drinks",
   "Description":"In the bar at\u00a0"
},
{
   "Date":"05/10/2019",
   "Time":"Morning",
   "Title":"Breakfast",
   "Description":"At leisure"
},
{
   "Date":"05/10/2019",
   "Time":"10:00",
   "Title":"Something Else",
   "Description":"At leisure"
}];

console.log(
  Object.values(input.reduce((a, { Date }) => {
    if (!a[Date]) a[Date] = { Date, activities: [] };
    a[Date].activities.push();
    return a;
  }, {}))
);

I need a combined object keys values in javascript in the following way:

[
   {
      "date":"04/10/2019",
      "activities":[
         {
            "Time":"15:35",
            "Title":"Flight -\u00a0Group C",
            "Description":"Arrival 19:40"
         },
         {
            "Time":"Evening",
            "Title":"Welcome drinks",
            "Description":"In the bar at\u00a0"
         }
      ]
   },
   {
      "date":"05/10/2019",
      "activities":[
         {
            "Time":"Morning",
            "Title":"Breakfast",
            "Description":"At leisure"
         }
      ]
   }
]

I am trying to get the result with my code but 'activities' are null... I would highly appreciate your help.

Thank you in advance

Technical but important note: by definition, JSON is pure string data. You can't "do" anything with it until you JSON.parse() it, the result of which is no longer JSON but is normal JS code (arrays, objects, etc). So if you're asking about grouping/sorting/etc, you're not asking about JSON. You're just trying to reorganise data inside plain JS data structures. — Mike 'Pomax' Kamermans
– Mike 'Pomax' Kamermans, Commented Feb 19, 2020 at 21:21
Does this answer your question? Group array of object nesting some of the keys with specific names — Heretic Monkey
– Heretic Monkey, Commented Feb 19, 2020 at 21:22

Nenad Vracar · Accepted Answer · 2020-02-19 21:24:22Z

2

If you are using parameter destructuring you could use ... rest param to get other properties after you take out the date.

const input=[{"Date":"04/10/2019","Time":"15:35","Title":"Flight - Group C","Description":"Arrival 19:40"},{"Date":"04/10/2019","Time":"Evening","Title":"Welcome drinks","Description":"In the bar at "},{"Date":"05/10/2019","Time":"Morning","Title":"Breakfast","Description":"At leisure"},{"Date":"05/10/2019","Time":"10:00","Title":"Something Else","Description":"At leisure"}]

const object = input.reduce((r, { Date: date, ...rest}) => {
  if(!r[date]) r[date] = {date, activities: [rest]}
  else r[date].activities.push(rest)
  return r
}, {})

const result = Object.values(object)
console.log(result)

answered Feb 19, 2020 at 21:24

Nenad Vracar

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