Merge and update methods in Ruby - Mini Project: Build & Apply

Merge and Update Methods

📖 Scenario: You are managing a small online store's inventory. You have a list of products with their current stock counts. Occasionally, you receive new shipments that update the stock counts or add new products.

🎯 Goal: Build a Ruby program that merges two hashes representing product stocks. The program will update existing products' stock counts and add new products from the shipment.

📋 What You'll Learn

Create a hash called current_stock with exact product names and stock counts

Create a hash called new_shipment with exact product names and stock counts

Use the merge! method with a block to update current_stock by adding stock counts from new_shipment

Print the updated current_stock hash

💡 Why This Matters

🌍 Real World

Managing inventory updates in small business software or online stores often requires merging stock data from different sources.

💼 Career

Understanding how to merge and update hashes is useful for backend developers working with data aggregation, inventory systems, or configuration management.

1

Create the current stock hash

Create a hash called current_stock with these exact entries: 'apple' => 30, 'banana' => 15, 'orange' => 20

Ruby

# Create the current_stock hash with given products and counts
# Your code here

Need a hint?

Use curly braces {} to create a hash. Separate keys and values with =>.

2

Create the new shipment hash

Create a hash called new_shipment with these exact entries: 'banana' => 10, 'orange' => 5, 'grape' => 12

Ruby

current_stock = { 'apple' => 30, 'banana' => 15, 'orange' => 20 }
# Create the new_shipment hash with given products and counts
# Your code here

Need a hint?

Use the same syntax as the first hash to create new_shipment.

3

Merge and update the stock counts

Use the merge! method on current_stock with new_shipment and a block that adds the old and new stock counts for matching products

Ruby

current_stock = { 'apple' => 30, 'banana' => 15, 'orange' => 20 }
new_shipment = { 'banana' => 10, 'orange' => 5, 'grape' => 12 }
# Merge new_shipment into current_stock, adding counts for duplicates
# Your code here

Need a hint?

The block receives the key, old value, and new value. Return the sum to update the stock count.

4

Print the updated stock

Print the current_stock hash to display the updated stock counts

Ruby

current_stock = { 'apple' => 30, 'banana' => 15, 'orange' => 20 }
new_shipment = { 'banana' => 10, 'orange' => 5, 'grape' => 12 }
current_stock.merge!(new_shipment) { |product, old_count, new_count| old_count + new_count }
# Print the updated current_stock hash
# Your code here

Need a hint?

Use puts to print the hash. The output shows the updated stock counts.