Home/ Questions/Q 14183
Next
In Process

askthedev.com Latest Questions

Asked: 2024-09-27T01:26:52+05:30 In:

How to Extract All Nested Keys from a JSON Object in Python?

I’ve been diving into JSON lately, and I bumped into a fun challenge that I thought might intrigue some of you! So, here’s the deal: Suppose you have a JSON object that represents some nested data, and I’m looking to extract just the keys from that object. Sounds simple enough, right? But here’s the twist: I want to get ALL the keys, no matter how deep they are nested!

Let’s say our JSON object looks something like this:

“`json
{
“name”: “Alice”,
“age”: 30,
“address”: {
“street”: “123 Main St”,
“city”: “Wonderland”,
“coordinates”: {
“latitude”: 37.1234,
“longitude”: -122.5678
}
},
“hobbies”: [“reading”, “chess”, “gardening”],
“work”: {
“title”: “Engineer”,
“skills”: {
“programming”: [“Python”, “JavaScript”],
“design”: [“Photoshop”, “Figma”]
}
}
}
“`

From this JSON, I’d want to end up with a flat list of all the keys, like this:

“`
name
age
address
street
city
coordinates
latitude
longitude
hobbies
work
title
skills
programming
design
“`

It seems like it could be an interesting little algorithmic challenge—especially if you try to write it in the fewest lines of code possible. I’m curious to see how different people might tackle this.

Would you go for a recursive approach, or do you have other clever methods up your sleeve? And how would you handle duplicates if there were any (like if keys were repeated at different levels)?

Also, is there a best way to sort these keys when you output them, or do you just keep the order they appear in?

I’d love to see some example solutions and hear your thoughts! How would you approach this problem?

Share

    Leave an answer

    You must login to add an answer.

    Need An Account,

    2 Answers

    1. Extracting Keys from Nested JSON

      So, I got really curious and tried to write a simple function to grab all the keys from our JSON object. Here’s what I came up with:

      function getAllKeys(obj) {
        let keys = [];
        
        function recurse(o) {
            for (let key in o) {
                keys.push(key); // Add the current key
                
                // If the value is an object (and not null), go deeper
                if (typeof o[key] === 'object' && o[key] !== null) {
                    recurse(o[key]);
                }
            }
        }
        
        recurse(obj);
        return keys;
    }

    // Example JSON object
    const jsonObject = {
        "name": "Alice",
        "age": 30,
        "address": {
            "street": "123 Main St",
            "city": "Wonderland",
            "coordinates": {
                "latitude": 37.1234,
                "longitude": -122.5678
            }
        },
        "hobbies": ["reading", "chess", "gardening"],
        "work": {
            "title": "Engineer",
            "skills": {
                "programming": ["Python", "JavaScript"],
                "design": ["Photoshop", "Figma"]
            }
        }
    };

    const keys = getAllKeys(jsonObject);
    console.log(keys); // This will give you an array of all keys

      This will print an array of all the keys in the JSON, no matter how deep they are. Pretty cool, right?

      Oh, and to handle duplicates, since we just want a flat list, this will work fine as it does not check for duplicates. But if at some point we wanted unique keys, we could use a Set. And about sorting, I think it’s nice to keep the order they appear. It feels more natural that way.

    2. To extract all keys from a nested JSON object, a recursive function is an efficient approach. This method allows you to traverse through each level of the object, collecting the keys as you go. The keys can be stored in a set to handle potential duplicates automatically. Below is a sample implementation in JavaScript that accomplishes this task.

      
function extractKeys(obj, prefix = '') {
    let keys = new Set(); // Using a Set to avoid duplicates

    for (let key in obj) {
        keys.add(prefix + key); // Add the current key, with prefix for nested keys
        if (typeof obj[key] === 'object' && obj[key] !== null) {
            // Recursively call for nested objects
            const childKeys = extractKeys(obj[key], prefix + key + '.');
            childKeys.forEach(k => keys.add(k));
        }
    }
    
    return Array.from(keys); // Convert Set back to Array for final output
}

// Example usage
const jsonData = {
    "name": "Alice",
    "age": 30,
    "address": {
        "street": "123 Main St",
        "city": "Wonderland",
        "coordinates": {
            "latitude": 37.1234,
            "longitude": -122.5678
        }
    },
    "hobbies": ["reading", "chess", "gardening"],
    "work": {
        "title": "Engineer",
        "skills": {
            "programming": ["Python", "JavaScript"],
            "design": ["Photoshop", "Figma"]
        }
    }
};

const allKeys = extractKeys(jsonData);
console.log(allKeys.sort()); // Outputs sorted keys

    Related Questions