CODEWITHSUNDEEP
javascriptlodash
Njuguna Mureithi
Njuguna Mureithi

Reputation: 3856

Need functional help handling this data structure

I have this data structure:

let questions=[{
    question: "What is your name?",
    responses: [{
        userId: 1,
        answer: "Geof"
    }, {
        userId: 5,
        answer: "Pete"
    }]
}, {
    question: "Where are you from?",
    responses: [{
        userId: 3,
        answer: "Earth"
    }, {
        userId: 5,
        answer: "Mars"
    }]
},.......]

I would like to spread this object to:

[{ userId: 1, "What is your name?": "geoff", "Where are you from?":"", "another question":....}, 
{ userId: 2, "What is your name?": "", "Where are you from?":"".......}

Since I cannot predict what questions that I get, I am looking for a dynamic function that spreads it this way. A solution with lodash is highly welcome.

Upvotes: 1

Views: 50

Answers (2)

Remo H. Jansen
Remo H. Jansen

Reputation: 24979

What about:

function formatAnswers(qs) {
    // Format into a map
    let users = {};
    qs.forEach((q) => {
        q.responses.forEach((r) => {
            if (users[r.userId] === undefined) {
                users[r.userId] = {
                    userId: r.userId,
                    [q.question]: r.answer
                };
            } else {
                users[r.userId][q.question] = r.answer;
            }
        });
    });
    // Transform map into an array
    let out = [];
    for (var entry in users) {
        out.push(users[entry]);
    }
    return out;
}

let result = formatAnswers(questions);
console.log(result);

Upvotes: 1

juvian
juvian

Reputation: 16068

let questions=[{
    question: "What is your name?",
    responses: [{
        userId: 1,
        answer: "Geof"
    }, {
        userId: 5,
        answer: "Pete"
    }]
}, {
    question: "Where are you from?",
    responses: [{
        userId: 3,
        answer: "Earth"
    }, {
        userId: 5,
        answer: "Mars"
    }]
}]

var responses = {}
questions.forEach(q => q.responses.forEach(res => (responses[res.userId] = responses[res.userId] || {})[q.question] = res.answer))
console.log(responses)

//If you really want it as array :

var arr = [];
for (var userId in responses) {
    responses[userId].userId = userId;
    arr.push(responses[userId]);
}

console.log(arr)

Note that this won´t store things like "What is your name?": "" but that is unnecesary, you can check with hasOwnProperty if a user has answered that question or not

Upvotes: 1

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