Finding an object in a nested object/array structure

Question

I have an app with a bunch of questions defined in a yaml file. For various reasons I would like the data to be divided into sections (section_0, section_1, section_2 etc.). When I load this file into my js app I get an object that looks like this:

const questionData = {
 "section_0": {
 "items": [
 {
 "key": "0.0",
 "title": "Question one",
 "type": "integer"
 },
 {
 "key": "0.1",
 "title": "Question 0.1",
 "type": "integer"
 }
 ]
 },
 "section_1": {
 "items": [
 {
 "key": "1.0",
 "title": "Some title",
 "type": "integer",
 "options": {
 "1": "one",
 "2": "two",
 "3": "other option"
 }
 },
 {
 "key": "1.1",
 "title": "Question 1.1",
 "description": "Longer description text",
 "type": "string"
 },
 {
 "key": "1.2",
 "title": "Question 1.2",
 "type": "integer",
 "options": {
 "0": "option zero",
 "1": "option one",
 "2": "option two"
 }
 },
 {
 "key": "1.3",
 "title": "Q 1.2",
 "type": "boolean",
 "options": {
 "true": "Yes",
 "false": "No"
 }
 },
 {
 "key": "1.4",
 "title": "Question 1.4",
 "type": "string"
 },
 {
 "key": "1.5",
 "title": "Question 1.5",
 "type": "integer"
 },
 {
 "key": "1.6",
 "title": "Question 1.6",
 "type": "integer"
 },
 {
 "key": "1.7",
 "title": "Q1.7",
 "type": "integer"
 }
 ]
 }
}

(a lot more questions and sections in the actual app)

Now I would like to be able to query for a question by the key. I found/figured out two ways to do this. One is sort of home made and the other flattens the array using lodash.

Traversing the object:

function findByKey(data, key){
 if (data.hasOwnProperty('key') && data['key'] === key) {
 return data;
 }
 for (let i = 0; i < Object.keys(data).length; i++) {
 if (typeof data[Object.keys(data)[i]] === 'object') {
 let obj = findByKey(data[Object.keys(data)[i]], key);
 if (obj != null) {
 return obj;
 }
 }
 }
 return null;
}
findByKey(questionData, "0.1")
// => returns the object with the key "0.1"

Using lodash to create a flat array of objects:

const questionsArray = _.flatten(_.map(_.keys(questionData), function(val) {
 return questionData[val].items;
}));
_.find(questionsArray, function(obj) { return obj.key === "0.1" })
// => returns the object with the key "0.1"

Do I need to transform the questionData object like this just to be able to query for an object somewhere in the tree or am I missing some simpler solution (other than not creating the nested structure in the first place)?

Answer 1

I usually have methods to normalize data in the format I want it so you don't have to iterate again. If you want you can have Schema that provides you methods or access to the data using custom methods.

var questions = new QuestionsSchema(data); // Normalizes to preferred format questions.getOriginal(); // => Access to the original object 
questions.getQuestion('0.1'); // => {"key": "0.0","title": "Question one","type": "integer"}
questions.getSection('section_1'); // => whole section

I like more the composed functions you build, is a more like functional way.