Scan with filter expressions in DynamoDB - Mini Project: Build & Apply

Scan with filter expressions

📖 Scenario: You are managing a DynamoDB table that stores information about books in a library. Each book has attributes like Title, Author, and Year. You want to find books published after the year 2000.

🎯 Goal: Build a DynamoDB scan operation with a filter expression to retrieve only books published after the year 2000.

📋 What You'll Learn

Create a dictionary called table_data with three books, each having Title, Author, and Year attributes.

Create a variable called year_threshold and set it to 2000.

Write a scan operation using a filter expression that selects books with Year greater than year_threshold.

Add the final step to execute the scan and store the filtered results in a variable called filtered_books.

💡 Why This Matters

🌍 Real World

Filtering data in DynamoDB tables is common when you want to retrieve only relevant items without fetching the entire table.

💼 Career

Understanding scan operations with filter expressions is essential for backend developers and database administrators working with AWS DynamoDB.

1

Create the initial table data

Create a dictionary called table_data with these exact entries: {'BookID1': {'Title': 'The Hobbit', 'Author': 'J.R.R. Tolkien', 'Year': 1937}, 'BookID2': {'Title': 'Harry Potter and the Goblet of Fire', 'Author': 'J.K. Rowling', 'Year': 2000}, 'BookID3': {'Title': 'The Da Vinci Code', 'Author': 'Dan Brown', 'Year': 2003}}

DynamoDB

# Create the table_data dictionary with the exact book entries
# Your code here

Need a hint?

Use a dictionary with keys as book IDs and values as dictionaries of book attributes.

2

Set the year threshold

Create a variable called year_threshold and set it to 2000.

DynamoDB

table_data = {
    'BookID1': {'Title': 'The Hobbit', 'Author': 'J.R.R. Tolkien', 'Year': 1937},
    'BookID2': {'Title': 'Harry Potter and the Goblet of Fire', 'Author': 'J.K. Rowling', 'Year': 2000},
    'BookID3': {'Title': 'The Da Vinci Code', 'Author': 'Dan Brown', 'Year': 2003}
}
# Create the year_threshold variable and set it to 2000
# Your code here

Need a hint?

Just assign the number 2000 to the variable year_threshold.

3

Write the scan with filter expression

Write a scan operation using a filter expression that selects books with Year greater than year_threshold. Use a variable called filtered_books to store the filtered results. Use a dictionary comprehension to filter table_data where the book's Year is greater than year_threshold.

DynamoDB

filtered_books = {book_id: info for book_id, info in table_data.items() if info['Year'] > year_threshold}
# Finalize the scan operation

Need a hint?

Use a dictionary comprehension with for book_id, info in table_data.items() and filter with if info['Year'] > year_threshold.

4

Complete the scan operation

Add the final step to execute the scan and store the filtered results in a variable called filtered_books. Ensure the code includes the full dictionary comprehension filtering table_data by Year greater than year_threshold.

DynamoDB

filtered_books = {book_id: info for book_id, info in table_data.items() if info['Year'] > year_threshold}

Need a hint?

The final step is to have the filtered_books variable assigned with the filtered dictionary comprehension.