Data aggregation patterns in Firebase - Mini Project: Build & Apply

Data Aggregation Patterns with Firebase

📖 Scenario: You are building a simple Firebase database to track sales data for a small store. Each sale records the product name and the quantity sold. You want to organize this data so you can easily find the total quantity sold for each product.

🎯 Goal: Create a Firebase Realtime Database structure to store sales data, add a configuration variable to filter products, write a query to aggregate total quantities sold per product, and finalize the database rules to allow read access.

📋 What You'll Learn

Create a Firebase Realtime Database node called sales with exact entries for three sales.

Add a configuration variable called filterProduct to select a product name.

Write a Firebase query to sum the quantities sold for the selected product.

Add database rules to allow read access to the sales node.

💡 Why This Matters

🌍 Real World

Stores and small businesses often track sales data in Firebase to analyze product performance and inventory needs.

💼 Career

Understanding data aggregation and Firebase rules is essential for cloud developers managing real-time databases and ensuring secure data access.

1

Create initial sales data in Firebase

Create a Firebase Realtime Database node called sales with these exact entries: sale1 with product: 'apple' and quantity: 10, sale2 with product: 'banana' and quantity: 5, and sale3 with product: 'apple' and quantity: 7.

Firebase

// Your code here to create sales data in Firebase

Need a hint?

Use a JavaScript object named sales with keys sale1, sale2, and sale3. Each key holds an object with product and quantity.

2

Add a filter configuration variable

Add a variable called filterProduct and set it to the string 'apple' to select the product to aggregate.

Firebase

const sales = {
  sale1: { product: 'apple', quantity: 10 },
  sale2: { product: 'banana', quantity: 5 },
  sale3: { product: 'apple', quantity: 7 }
};
// Your code here to add filterProduct variable

Need a hint?

Declare a constant named filterProduct and assign it the string 'apple'.

3

Aggregate total quantity for the filtered product

Write code to calculate the total quantity sold for the product stored in filterProduct. Use a for loop with variables saleKey and sale to iterate over Object.entries(sales). Sum the quantity of sales where sale.product === filterProduct into a variable called totalQuantity.

Firebase

const sales = {
  sale1: { product: 'apple', quantity: 10 },
  sale2: { product: 'banana', quantity: 5 },
  sale3: { product: 'apple', quantity: 7 }
};

const filterProduct = 'apple';

// Your code here to calculate totalQuantity

Need a hint?

Initialize totalQuantity to 0. Use a for loop with saleKey and sale from Object.entries(sales). Inside the loop, add sale.quantity to totalQuantity only if sale.product matches filterProduct.

4

Add Firebase database rules for read access

Add Firebase Realtime Database rules to allow read access to the sales node for all users. The rules should have a rules object with a sales child that has .read set to true.

Firebase

const sales = {
  sale1: { product: 'apple', quantity: 10 },
  sale2: { product: 'banana', quantity: 5 },
  sale3: { product: 'apple', quantity: 7 }
};

const filterProduct = 'apple';

let totalQuantity = 0;
for (const [saleKey, sale] of Object.entries(sales)) {
  if (sale.product === filterProduct) {
    totalQuantity += sale.quantity;
  }
}

// Your code here to add Firebase database rules

Need a hint?

Define a constant databaseRules with a rules object. Inside rules, add a sales object with '.read' set to true.