How to replace nested objects in a TypeScript object

Question

What I need to do is modify a TypeScript object by doing a key search (the key can be repeated, so I need to check that it belongs to the right branch) and modifying the corresponding object. In short if this is the object:

{
   requirements: {
     general_info: {
       aircraft: {
         payload: { '@_unit': 'kg' },
         autopilot_ratio: '',
       },
       power: {
         number_of_engines: '',
       },
       geometrical: {
         payload: { '@_unit': 'kg' },
         design_approach: { target: '' },
       },
     },
   },
}

must be transformed into:

{
   requirements: {
     general_info: {
       aircraft: {
         payload: { '@_unit': 'hg', '#text': 3000},
         autopilot_ratio: '',
       },
       power: {
         number_of_engines: '',
       },
       geometrical: {
         payload: { '@_unit': 'kg' },
         design_approach: { target: '' },
       },
     },
   },
}

I understand that it has to be a recursive function. I tried to write the following function but I don't know how to prevent nested objects from being inserted multiple times

const updateObject = (json: any, searchKey: string, unit: string, value: number): Object => {
  return Object.keys(json).map((key: string) => {
    if (key !== searchKey && typeof json[key] !== 'string') {
      return updateObject(json[key], searchKey, unit, value);
    } else {
      if (typeof json[key] !== 'string') {
        json[key]['@_unit'] = unit;
        json[key]['#text'] = value;
        return json;
      } else {
        return json;
      }
    }
  });
};

console.dir(updateObject(json, 'payload', 'hg', 3000), { depth: null });

Among other things, this changes all the payload instances, it would also be useful to pass requirements.general_info.aircraft.payload as searchKey so as to change only the desired one

EDIT The object { '@_unit': 'kg' } has a fixed format and I can already know a priori that it will be { '@_unit': 'hg', '#text': 3000} the problem is but replace it in the right place of the JSON because it is not unique, otherwise a JSON.parse(JSON.stringify(json).replace() would have been enough.

"I understand that it has to be a recursive function..." Does it? In your example, payload only appears at a single level in the object tree (as a child of a child of a child of requirements). You don't need a recursive function if that's the case. — T.J. Crowder
– T.J. Crowder, Commented Oct 20, 2023 at 9:23
You're probably right, it's the only way I've found to cycle through nested objects — 3corex
– 3corex, Commented Oct 20, 2023 at 9:29
If you already have the path to the object to update (ie requirements.general_info.aircraft.payload) you could use something like JSONPath to get the correct object. If you don't have the full path, you do you determine, whether to update or not a certain payload object (ie you want to update the payload of the aircraft object but not of the geometrical — derpirscher
– derpirscher, Commented Oct 20, 2023 at 9:40
Does this answer your question? JavaScript - retrieve value from nested object, using array of keys — derpirscher
– derpirscher, Commented Oct 20, 2023 at 9:44

3corex · Accepted Answer · 2023-10-21 12:21:20Z

0

Thanks to the comments of T.J. Crowder and derpirscher I wrote a non-recursive function that solves the problem:

const path = 'requirements.general_info.aircraft.payload';
const modifiedJsonData = updateObject(jsonData, path, 'hg', 3000);

const updateObject = (json: any, path: string, unit: string, value: number): Object => {
  const pathKeys = path.split('.');

  if (allObjectPaths(json).includes(path)) {
    let temp = json;
    pathKeys.forEach((key: string) => {
      temp = temp[key];
    });
    temp['@_unit'] = unit;
    temp['#text'] = value;
    return json;
  } else {
    throw new Error('Path is incorrect');
  }
};

answered Oct 21, 2023 at 12:21

3corex

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Comments

user14967413 · Accepted Answer · 2023-10-20 10:19:39Z

-2

Try using lodash.

import _ from 'lodash'

function updateObject(json: any, path: _.PropertyPath, unit: string, value: number) {
  if (_.has(json, path)) {
    _.setWith(json, path, { '@unit': unit, '#text': value })
  }
  return json
}

let path = 'requirements.general_info.aircraft.payload'
// alternatively:
// path = ['requirements', 'general_info', 'aircraft', 'payload']
console.dir(updateObject(json, path, 'hg', 3000), { depth:null })

Remember to install lodash as well as its type definitions.

npm -i lodash
npm -i --save-dev @types/lodash

answered Oct 20, 2023 at 10:19

user14967413

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1 Comment

3corex Over a year ago

Works great (we won't get rid of Lodash that easily... :D)

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