Applying Data Filtering and Aggregation with a User Management System in JavaScript

Introduction

Welcome to today's lesson on applying data filtering and aggregation in a real-world scenario using a user management system. We'll start by building a foundational structure that can handle basic user operations. Then, we'll expand it by introducing more advanced functionalities that allow filtering and aggregating user data.

Starter Task Methods

In our starter task, we will implement a class that manages basic operations on a collection of user data, specifically handling adding new users, retrieving user profiles, and updating user profiles. Here are the starter task methods: addUser(userId, age, country, subscribed) - adds a new user with the specified attributes. Returns true if the user was added successfully and false if a user with the same userId already exists. getUser(userId) - returns the user's profile as an object if the user exists; otherwise, returns null . updateUser(userId, age, country, subscribed) - updates the user's profile based on non- null parameters. Returns true if the user exists and was updated, false otherwise.

Solution for the Starter Task

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JavaScript

class UserManager {
    constructor() {
        this.users = {};  // Initialize an empty object to store user data
    }
    
    // Method to add a new user
    addUser(userId, age, country, subscribed) {
        if (this.users[userId]) {
            return false;  // Return false if userId already exists
        }
        this.users[userId] = { age, country, subscribed };  // Add user to the users object
        return true;  // Return true to indicate successful addition
    }

    // Method to retrieve a user's profile
    getUser(userId) {
        return this.users[userId] || null;  // Return the user profile or null if the user does not exist
    }

    // Method to update a user's profile
    updateUser(userId, age, country, subscribed) {
        if (!this.users[userId]) {
            return false;  // Return false if the user does not exist
        }
        if (age !== null) {
            this.users[userId].age = age;  // Update age if provided
        }
        if (country !== null) {
            this.users[userId].country = country;  // Update country if provided
        }
        if (subscribed !== null) {
            this.users[userId].subscribed = subscribed;  // Update subscription status if provided
        }
        return true;  // Return true to indicate successful update
    }
}

// Example usage
const um = new UserManager();
console.log(um.addUser("u1", 25, "USA", true));  // true
console.log(um.addUser("u2", 30, "Canada", false));  // true
console.log(um.addUser("u1", 22, "Mexico", true));  // false
console.log(um.getUser("u1"));  // { age: 25, country: "USA", subscribed: true }
console.log(um.updateUser("u1", 26, null, null));  // true
console.log(um.updateUser("u3", 19, "UK", false));  // false

JavaScript

class UserManager {
    // Existing methods...

    // Method to filter users based on criteria
    filterUsers(minAge, maxAge, country, subscribed) {
        const filteredUsers = [];
        for (const [userId, profile] of Object.entries(this.users)) {
            // Check minimum age criterion
            if (minAge !== null && profile.age < minAge) {
                continue;
            }
            // Check maximum age criterion
            if (maxAge !== null && profile.age > maxAge) {
                continue;
            }
            // Check country criterion
            if (country !== null && profile.country !== country) {
                continue;
            }
            // Check subscription status criterion
            if (subscribed !== null && profile.subscribed !== subscribed) {
                continue;
            }
            // Add userId to filteredUsers if all criteria are met
            filteredUsers.push(userId);
        }
        return filteredUsers;  // Return the list of filtered user IDs
    }
}

// Example usage of the new method
const um = new UserManager();
um.addUser("u1", 25, "USA", true);
um.addUser("u2", 30, "Canada", false);
um.addUser("u3", 22, "USA", true);
console.log(um.filterUsers(20, 30, "USA", true));  // ["u1", "u3"]
console.log(um.filterUsers(null, 28, null, null));  // ["u1", "u3"]
console.log(um.filterUsers(null, null, "Canada", false));  // ["u2"]

class UserManager {
    // Existing methods...

    // Method to filter users based on criteria
    filterUsers(minAge, maxAge, country, subscribed) {
        const filteredUsers = [];
        for (const [userId, profile] of Object.entries(this.users)) {
            // Check minimum age criterion
            if (minAge !== null && profile.age < minAge) {
                continue;
            }
            // Check maximum age criterion
            if (maxAge !== null && profile.age > maxAge) {
                continue;
            }
            // Check country criterion
            if (country !== null && profile.country !== country) {
                continue;
            }
            // Check subscription status criterion
            if (subscribed !== null && profile.subscribed !== subscribed) {
                continue;
            }
            // Add userId to filteredUsers if all criteria are met
            filteredUsers.push(userId);
        }
        return filteredUsers;  // Return the list of filtered user IDs
    }
}

// Example usage of the new method
const um = new UserManager();
um.addUser("u1", 25, "USA", true);
um.addUser("u2", 30, "Canada", false);
um.addUser("u3", 22, "USA", true);
console.log(um.filterUsers(20, 30, "USA", true));  // ["u1", "u3"]
console.log(um.filterUsers(null, 28, null, null));  // ["u1", "u3"]
console.log(um.filterUsers(null, null, "Canada", false));  // ["u2"]

JavaScript

class UserManager {
    // Existing methods...

    // Method to aggregate statistics from user profiles
    aggregateStats() {
        const totalUsers = Object.keys(this.users).length;  // Get the total number of users
        if (totalUsers === 0) {  // If no users, return zeroed statistics
            return { totalUsers: 0, averageAge: 0, subscribedRatio: 0.00 };
        }
        
        // Calculate total age by summing ages of all users
        const totalAge = Object.values(this.users).reduce((sum, profile) => sum + profile.age, 0);
        // Count number of subscribed users
        const subscribedUsers = Object.values(this.users).filter(profile => profile.subscribed).length;
        
        // Calculate average age (rounded down)
        const averageAge = Math.floor(totalAge / totalUsers);
        // Calculate subscribed ratio (to two decimals)
        const subscribedRatio = (subscribedUsers / totalUsers).toFixed(2);
        
        return { totalUsers, averageAge, subscribedRatio: parseFloat(subscribedRatio) };  // Return statistics object
    }
}

// Using `um` from the previous section
console.log(um.aggregateStats());  // { totalUsers: 3, averageAge: 25, subscribedRatio: 0.67 }

class UserManager {
    // Existing methods...

    // Method to aggregate statistics from user profiles
    aggregateStats() {
        const totalUsers = Object.keys(this.users).length;  // Get the total number of users
        if (totalUsers === 0) {  // If no users, return zeroed statistics
            return { totalUsers: 0, averageAge: 0, subscribedRatio: 0.00 };
        }
        
        // Calculate total age by summing ages of all users
        const totalAge = Object.values(this.users).reduce((sum, profile) => sum + profile.age, 0);
        // Count number of subscribed users
        const subscribedUsers = Object.values(this.users).filter(profile => profile.subscribed).length;
        
        // Calculate average age (rounded down)
        const averageAge = Math.floor(totalAge / totalUsers);
        // Calculate subscribed ratio (to two decimals)
        const subscribedRatio = (subscribedUsers / totalUsers).toFixed(2);
        
        return { totalUsers, averageAge, subscribedRatio: parseFloat(subscribedRatio) };  // Return statistics object
    }
}

// Using `um` from the previous section
console.log(um.aggregateStats());  // { totalUsers: 3, averageAge: 25, subscribedRatio: 0.67 }

JavaScript

class UserManager {
    constructor() {
        this.users = {};  // Initialize an empty object to store user data
    }

    // Method to add a new user
    addUser(userId, age, country, subscribed) {
        if (this.users[userId]) {
            return false;  // Return false if userId already exists
        }
        this.users[userId] = { age, country, subscribed };  // Add user to the users object
        return true;  // Return true to indicate successful addition
    }

    // Method to retrieve a user's profile
    getUser(userId) {
        return this.users[userId] || null;  // Return the user profile or null if the user does not exist
    }

    // Method to update a user's profile
    updateUser(userId, age, country, subscribed) {
        if (!this.users[userId]) {
            return false;  // Return false if the user does not exist
        }
        if (age !== null) {
            this.users[userId].age = age;  // Update age if provided
        }
        if (country !== null) {
            this.users[userId].country = country;  // Update country if provided
        }
        if (subscribed !== null) {
            this.users[userId].subscribed = subscribed;  // Update subscription status if provided
        }
        return true;  // Return true to indicate successful update
    }

    // Method to filter users based on criteria
    filterUsers(minAge, maxAge, country, subscribed) {
        const filteredUsers = [];
        for (const [userId, profile] of Object.entries(this.users)) {
            // Check minimum age criterion
            if (minAge !== null && profile.age < minAge) {
                continue;
            }
            // Check maximum age criterion
            if (maxAge !== null && profile.age > maxAge) {
                continue;
            }
            // Check country criterion
            if (country !== null && profile.country !== country) {
                continue;
            }
            // Check subscription status criterion
            if (subscribed !== null && profile.subscribed !== subscribed) {
                continue;
            }
            // Add userId to filteredUsers if all criteria are met
            filteredUsers.push(userId);
        }
        return filteredUsers;  // Return the list of filtered user IDs
    }

    // Method to aggregate statistics from user profiles
    aggregateStats() {
        const totalUsers = Object.keys(this.users).length;  // Get the total number of users
        if (totalUsers === 0) {  // If no users, return zeroed statistics
            return { totalUsers: 0, averageAge: 0, subscribedRatio: 0.00 };
        }
        
        // Calculate total age by summing ages of all users
        const totalAge = Object.values(this.users).reduce((sum, profile) => sum + profile.age, 0);
        // Count number of subscribed users
        const subscribedUsers = Object.values(this.users).filter(profile => profile.subscribed).length;
        
        // Calculate average age (rounded down)
        const averageAge = Math.floor(totalAge / totalUsers);
        // Calculate subscribed ratio (to two decimals)
        const subscribedRatio = (subscribedUsers / totalUsers).toFixed(2);
        
        return { totalUsers, averageAge, subscribedRatio: parseFloat(subscribedRatio) };  // Return statistics object
    }
}

// Example usage
const um = new UserManager();
um.addUser("u1", 25, "USA", true);
um.addUser("u2", 30, "Canada", false);
um.addUser("u3", 22, "USA", true);

console.log(um.filterUsers(20, 30, "USA", true));  // ["u1", "u3"]
console.log(um.filterUsers(null, 28, null, null));  // ["u1", "u3"]
console.log(um.filterUsers(null, null, "Canada", false));  // ["u2"]

console.log(um.aggregateStats());  // { totalUsers: 3, averageAge: 25, subscribedRatio: 0.67 }

class UserManager {
    constructor() {
        this.users = {};  // Initialize an empty object to store user data
    }

    // Method to add a new user
    addUser(userId, age, country, subscribed) {
        if (this.users[userId]) {
            return false;  // Return false if userId already exists
        }
        this.users[userId] = { age, country, subscribed };  // Add user to the users object
        return true;  // Return true to indicate successful addition
    }

    // Method to retrieve a user's profile
    getUser(userId) {
        return this.users[userId] || null;  // Return the user profile or null if the user does not exist
    }

    // Method to update a user's profile
    updateUser(userId, age, country, subscribed) {
        if (!this.users[userId]) {
            return false;  // Return false if the user does not exist
        }
        if (age !== null) {
            this.users[userId].age = age;  // Update age if provided
        }
        if (country !== null) {
            this.users[userId].country = country;  // Update country if provided
        }
        if (subscribed !== null) {
            this.users[userId].subscribed = subscribed;  // Update subscription status if provided
        }
        return true;  // Return true to indicate successful update
    }

    // Method to filter users based on criteria
    filterUsers(minAge, maxAge, country, subscribed) {
        const filteredUsers = [];
        for (const [userId, profile] of Object.entries(this.users)) {
            // Check minimum age criterion
            if (minAge !== null && profile.age < minAge) {
                continue;
            }
            // Check maximum age criterion
            if (maxAge !== null && profile.age > maxAge) {
                continue;
            }
            // Check country criterion
            if (country !== null && profile.country !== country) {
                continue;
            }
            // Check subscription status criterion
            if (subscribed !== null && profile.subscribed !== subscribed) {
                continue;
            }
            // Add userId to filteredUsers if all criteria are met
            filteredUsers.push(userId);
        }
        return filteredUsers;  // Return the list of filtered user IDs
    }

    // Method to aggregate statistics from user profiles
    aggregateStats() {
        const totalUsers = Object.keys(this.users).length;  // Get the total number of users
        if (totalUsers === 0) {  // If no users, return zeroed statistics
            return { totalUsers: 0, averageAge: 0, subscribedRatio: 0.00 };
        }
        
        // Calculate total age by summing ages of all users
        const totalAge = Object.values(this.users).reduce((sum, profile) => sum + profile.age, 0);
        // Count number of subscribed users
        const subscribedUsers = Object.values(this.users).filter(profile => profile.subscribed).length;
        
        // Calculate average age (rounded down)
        const averageAge = Math.floor(totalAge / totalUsers);
        // Calculate subscribed ratio (to two decimals)
        const subscribedRatio = (subscribedUsers / totalUsers).toFixed(2);
        
        return { totalUsers, averageAge, subscribedRatio: parseFloat(subscribedRatio) };  // Return statistics object
    }
}

// Example usage
const um = new UserManager();
um.addUser("u1", 25, "USA", true);
um.addUser("u2", 30, "Canada", false);
um.addUser("u3", 22, "USA", true);

console.log(um.filterUsers(20, 30, "USA", true));  // ["u1", "u3"]
console.log(um.filterUsers(null, 28, null, null));  // ["u1", "u3"]
console.log(um.filterUsers(null, null, "Canada", false));  // ["u2"]

console.log(um.aggregateStats());  // { totalUsers: 3, averageAge: 25, subscribedRatio: 0.67 }

JavaScript

class UserManager {
    // Existing methods...

    // Method to filter users based on criteria
    filterUsers(minAge, maxAge, country, subscribed) {
        const filteredUsers = [];
        for (const [userId, profile] of Object.entries(this.users)) {
            // Check minimum age criterion
            if (minAge !== null && profile.age < minAge) {
                continue;
            }
            // Check maximum age criterion
            if (maxAge !== null && profile.age > maxAge) {
                continue;
            }
            // Check country criterion
            if (country !== null && profile.country !== country) {
                continue;
            }
            // Check subscription status criterion
            if (subscribed !== null && profile.subscribed !== subscribed) {
                continue;
            }
            // Add userId to filteredUsers if all criteria are met
            filteredUsers.push(userId);
        }
        return filteredUsers;  // Return the list of filtered user IDs
    }
}

// Example usage of the new method
const um = new UserManager();
um.addUser("u1", 25, "USA", true);
um.addUser("u2", 30, "Canada", false);
um.addUser("u3", 22, "USA", true);
console.log(um.filterUsers(20, 30, "USA", true));  // ["u1", "u3"]
console.log(um.filterUsers(null, 28, null, null));  // ["u1", "u3"]
console.log(um.filterUsers(null, null, "Canada", false));  // ["u2"]

JavaScript

class UserManager {
    // Existing methods...

    // Method to aggregate statistics from user profiles
    aggregateStats() {
        const totalUsers = Object.keys(this.users).length;  // Get the total number of users
        if (totalUsers === 0) {  // If no users, return zeroed statistics
            return { totalUsers: 0, averageAge: 0, subscribedRatio: 0.00 };
        }
        
        // Calculate total age by summing ages of all users
        const totalAge = Object.values(this.users).reduce((sum, profile) => sum + profile.age, 0);
        // Count number of subscribed users
        const subscribedUsers = Object.values(this.users).filter(profile => profile.subscribed).length;
        
        // Calculate average age (rounded down)
        const averageAge = Math.floor(totalAge / totalUsers);
        // Calculate subscribed ratio (to two decimals)
        const subscribedRatio = (subscribedUsers / totalUsers).toFixed(2);
        
        return { totalUsers, averageAge, subscribedRatio: parseFloat(subscribedRatio) };  // Return statistics object
    }
}

// Using `um` from the previous section
console.log(um.aggregateStats());  // { totalUsers: 3, averageAge: 25, subscribedRatio: 0.67 }

JavaScript

class UserManager {
    constructor() {
        this.users = {};  // Initialize an empty object to store user data
    }

    // Method to add a new user
    addUser(userId, age, country, subscribed) {
        if (this.users[userId]) {
            return false;  // Return false if userId already exists
        }
        this.users[userId] = { age, country, subscribed };  // Add user to the users object
        return true;  // Return true to indicate successful addition
    }

    // Method to retrieve a user's profile
    getUser(userId) {
        return this.users[userId] || null;  // Return the user profile or null if the user does not exist
    }

    // Method to update a user's profile
    updateUser(userId, age, country, subscribed) {
        if (!this.users[userId]) {
            return false;  // Return false if the user does not exist
        }
        if (age !== null) {
            this.users[userId].age = age;  // Update age if provided
        }
        if (country !== null) {
            this.users[userId].country = country;  // Update country if provided
        }
        if (subscribed !== null) {
            this.users[userId].subscribed = subscribed;  // Update subscription status if provided
        }
        return true;  // Return true to indicate successful update
    }

    // Method to filter users based on criteria
    filterUsers(minAge, maxAge, country, subscribed) {
        const filteredUsers = [];
        for (const [userId, profile] of Object.entries(this.users)) {
            // Check minimum age criterion
            if (minAge !== null && profile.age < minAge) {
                continue;
            }
            // Check maximum age criterion
            if (maxAge !== null && profile.age > maxAge) {
                continue;
            }
            // Check country criterion
            if (country !== null && profile.country !== country) {
                continue;
            }
            // Check subscription status criterion
            if (subscribed !== null && profile.subscribed !== subscribed) {
                continue;
            }
            // Add userId to filteredUsers if all criteria are met
            filteredUsers.push(userId);
        }
        return filteredUsers;  // Return the list of filtered user IDs
    }

    // Method to aggregate statistics from user profiles
    aggregateStats() {
        const totalUsers = Object.keys(this.users).length;  // Get the total number of users
        if (totalUsers === 0) {  // If no users, return zeroed statistics
            return { totalUsers: 0, averageAge: 0, subscribedRatio: 0.00 };
        }
        
        // Calculate total age by summing ages of all users
        const totalAge = Object.values(this.users).reduce((sum, profile) => sum + profile.age, 0);
        // Count number of subscribed users
        const subscribedUsers = Object.values(this.users).filter(profile => profile.subscribed).length;
        
        // Calculate average age (rounded down)
        const averageAge = Math.floor(totalAge / totalUsers);
        // Calculate subscribed ratio (to two decimals)
        const subscribedRatio = (subscribedUsers / totalUsers).toFixed(2);
        
        return { totalUsers, averageAge, subscribedRatio: parseFloat(subscribedRatio) };  // Return statistics object
    }
}

// Example usage
const um = new UserManager();
um.addUser("u1", 25, "USA", true);
um.addUser("u2", 30, "Canada", false);
um.addUser("u3", 22, "USA", true);

console.log(um.filterUsers(20, 30, "USA", true));  // ["u1", "u3"]
console.log(um.filterUsers(null, 28, null, null));  // ["u1", "u3"]
console.log(um.filterUsers(null, null, "Canada", false));  // ["u2"]

console.log(um.aggregateStats());  // { totalUsers: 3, averageAge: 25, subscribedRatio: 0.67 }

Introduction

Starter Task Methods

Solution for the Starter Task

Join the 1M+ learners on CodeSignal

Introducing New Methods for Data Filtering and Aggregation

Step-by-Step Implementation: Step 1: Adding `filterUsers` Method

Step 2: Adding `aggregateStats` Method

The Final Solution

Lesson Summary