JS - Transform Nested array of JSON into single Object

Question

I want to transform the nested JSON structure into a single object, with the dynamic key I tried with below code but it's work only with one level, I need to write some recursive function, that I am struggling to write the code for n level of nested JSON. Please advise.

   data.map((e) => {
   for (let key in e) {
     if (typeof e[key] === "object") {
       for (let onLevel in e[key]) {
         e[key + "." + onLevel] = e[key][onLevel];
       }
     }
   }
 });

Example

Input JSON

[{
  "Id": "0hb3L00000000jkQAA",
  "Name": "P-2797",
  "ContactEncounterId": "0ha3L000000001qQAA",
  "StartTime": "2020-06-27T11:00:00.000Z",
  "EncounterDuration": 25,
  "ContactEncounter": {
    "Name": "Grocery Shopping 17",
    "LocationId": "1313L0000004ENlQAM",
    "Id": "0ha3L000000001qQAA",
    "Location": {
      "Name": "Waitrose",
      "LocationType": "Site",
      "Id": "1313L0000004ENlQAM"
    }
  }
}]

OutPut JSON

[{
  "Id": "0hb3L00000000jkQAA",
  "Name": "P-2797",
  "ContactEncounterId": "0ha3L000000001qQAA",
  "StartTime": "2020-06-27T11:00:00.000Z",
  "EncounterDuration": 25,
  "ContactEncounter.Name": "Grocery Shopping 17",
  "ContactEncounter.LocationId": "1313L0000004ENlQAM",
  "ContactEncounter.Id": "0ha3L000000001qQAA",
  "ContactEncounter.Location.Name": "Waitrose",
  "ContactEncounter.Location.LocationType": "Site",
  "ContactEncounter.Location.Id": "1313L0000004ENlQAM"
}]

Answer 1

As you said, you need to create a recursion to get deeper into the object. Which means, you would have to track the path where you are.

You could solve it in the following way

 const input = [{ "Id": "0hb3L00000000jkQAA", "Name": "P-2797", "ContactEncounterId": "0ha3L000000001qQAA", "StartTime": "2020-06-27T11:00:00.000Z", "EncounterDuration": 25, "ContactEncounter": { "Name": "Grocery Shopping 17", "LocationId": "1313L0000004ENlQAM", "Id": "0ha3L000000001qQAA", "Location": { "Name": "Waitrose", "LocationType": "Site", "Id": "1313L0000004ENlQAM" } } } ]; function merge( source, target = {}, ...parents) { for (let [key, value] of Object.entries( source ) ) { const path = (parents || []).concat( key ); if (typeof value === 'object') { merge( value, target, ...path ); continue; } target[path.join('.')] = value; } return target; } console.log( merge( input[0] ) );

Or in the following way, where you just use Object.assign to assign the results of the deeper search into your current object.

 const input = [{ "Id": "0hb3L00000000jkQAA", "Name": "P-2797", "ContactEncounterId": "0ha3L000000001qQAA", "StartTime": "2020-06-27T11:00:00.000Z", "EncounterDuration": 25, "ContactEncounter": { "Name": "Grocery Shopping 17", "LocationId": "1313L0000004ENlQAM", "Id": "0ha3L000000001qQAA", "Location": { "Name": "Waitrose", "LocationType": "Site", "Id": "1313L0000004ENlQAM" } } } ]; function merge( source, ...parents) { const mergedValue = {}; for (let [key, value] of Object.entries( source ) ) { const path = (parents || []).concat( key ); if (typeof value === 'object') { Object.assign( mergedValue, merge( value, ...path ) ); continue; } mergedValue[path.join('.')] = value; } return mergedValue; } console.log( merge( input[0] ) );

Answer 2

Here is another approach by using the second parameter and passing the key when finding a nth level object.

 const obj = { "Id": "0hb3L00000000jkQAA", "Name": "P-2797", "ContactEncounterId": "0ha3L000000001qQAA", "StartTime": "2020-06-27T11:00:00.000Z", "EncounterDuration": 25, "ContactEncounter": { "Name": "Grocery Shopping 17", "LocationId": "1313L0000004ENlQAM", "Id": "0ha3L000000001qQAA", "Location": { "Name": "Waitrose", "LocationType": "Site", "Id": "1313L0000004ENlQAM" } } } function flattenObj(obj, param) { let newObj = {}; for (let key in obj) { if (typeof obj[key] === 'object') { newObj = { ...newObj, ...flattenObj(obj[key], key + '.') } } else { newObj[param + key] = obj[key] } } return newObj; } console.log(flattenObj(obj, ''))