I am trying to get values from an JSON file by matching key names, but it does not work with nested keys

Question

I am trying to key values from an JSON file by matching key names, but it does not work with nested keys, maybe not the best way to load date this way(if there are better ways to do this let me know).

// .JSON file

{
    "routes":{
        "path":{
            "register":{
                "index": "register"
            },
            "login":{
                "index": "login"
            }
            ...
        }
    }
}

// solution(not working)

const paths = require(`../locales/en-US.json`)
const getByValueByKey = (getPath, value) => {
    for (let key of Object.keys(getPath)) {
        if (getPath[key] === value) {
            return key;
        }
    }
}

getByValueByKey(paths, 'routes.path.login.index')//should return login

What don't you access `paths.routes.path.login.index` directly? — Felix Kling, Jun 10 '21 at 11:04

score 1 · Answer 1 · answered Jun 10 '21 at 11:04

You can use lodash's get method - https://lodash.com/docs/4.17.15#get.

This is the source code for that method if you want a native implementation:

 /**
     * The base implementation of `_.get` without support for default values.
     *
     * @private
     * @param {Object} object The object to query.
     * @param {Array|string} path The path of the property to get.
     * @returns {*} Returns the resolved value.
     */
    function baseGet(object, path) {
      path = castPath(path, object);

      var index = 0,
          length = path.length;

      while (object != null && index < length) {
        object = object[toKey(path[index++])];
      }
      return (index && index == length) ? object : undefined;
    }

    function get(object, path, defaultValue) {
      var result = object == null ? undefined : baseGet(object, path);
      return result === undefined ? defaultValue : result;
    }

The lodash way is just one way :), you can use that or the solution provided below by @decpk, both are good. — John, Jun 10 '21 at 11:23

DecPK · Accepted Answer · 2021-06-10T11:10:46.173

You can use reduce and get the value.

const result = value.split(".").reduce((acc, curr) => acc && acc[curr], getPath);

const paths = {
  routes: {
    path: {
      register: {
        index: "register",
      },
      login: {
        index: "login",
      },
    },
  },
};

const getByValueByKey = (getPath, value) => {
const result = value.split(".").reduce((acc, curr) => acc && acc[curr], getPath);
  console.log(result);
};

getByValueByKey(paths, "routes.path.login.index"); //should return login

I am trying to get values from an JSON file by matching key names, but it does not work with nested keys

2 Answers2