Query by partition key in DynamoDB - Mini Project: Build & Apply

Query Items by Partition Key in DynamoDB

📖 Scenario: You are managing a DynamoDB table that stores information about books in a library. Each book has a unique ISBN as the partition key and contains details like Title and Author.You want to retrieve all information about a specific book by querying the table using its ISBN.

🎯 Goal: Build a DynamoDB query that fetches all attributes of a book using its ISBN as the partition key.

📋 What You'll Learn

Create a dictionary called book_item with the exact keys: 'ISBN', 'Title', and 'Author' with given values.

Create a variable called isbn_to_query and set it to the exact string value of the ISBN you want to query.

Write a query expression dictionary called query_params that uses isbn_to_query as the partition key value for the KeyConditionExpression.

Add the final call to dynamodb_client.query() with query_params to complete the query setup.

💡 Why This Matters

🌍 Real World

Querying by partition key is a common operation to retrieve specific items quickly from DynamoDB tables in real-world applications like inventory systems, user profiles, or product catalogs.

💼 Career

Understanding how to query DynamoDB by partition key is essential for backend developers and cloud engineers working with AWS services to build scalable and efficient data-driven applications.

1

Create the book item dictionary

Create a dictionary called book_item with these exact entries: 'ISBN': '978-0132350884', 'Title': 'Clean Code', and 'Author': 'Robert C. Martin'.

DynamoDB

# Create the book_item dictionary with ISBN, Title, and Author
# Your code here

Need a hint?

Use curly braces {} to create a dictionary with the exact keys and values.

2

Set the ISBN to query

Create a variable called isbn_to_query and set it to the string '978-0132350884'.

DynamoDB

book_item = {'ISBN': '978-0132350884', 'Title': 'Clean Code', 'Author': 'Robert C. Martin'}
# Create isbn_to_query variable with the exact ISBN string
# Your code here

Need a hint?

Assign the exact ISBN string to the variable isbn_to_query.

3

Create the query parameters dictionary

Create a dictionary called query_params with the keys TableName set to 'Books', and KeyConditionExpression set to 'ISBN = :isbn'. Also add ExpressionAttributeValues with {':isbn': {'S': isbn_to_query}}.

DynamoDB

book_item = {'ISBN': '978-0132350884', 'Title': 'Clean Code', 'Author': 'Robert C. Martin'}
isbn_to_query = '978-0132350884'
# Create query_params dictionary with TableName, KeyConditionExpression, and ExpressionAttributeValues
# Your code here

Need a hint?

Use the exact keys and values as shown to build the query parameters dictionary.

4

Complete the query call

Add a line that calls dynamodb_client.query() with the argument **query_params to perform the query.

DynamoDB

book_item = {'ISBN': '978-0132350884', 'Title': 'Clean Code', 'Author': 'Robert C. Martin'}
isbn_to_query = '978-0132350884'
query_params = {
    'TableName': 'Books',
    'KeyConditionExpression': 'ISBN = :isbn',
    'ExpressionAttributeValues': {':isbn': {'S': isbn_to_query}}
}
# Call dynamodb_client.query() with query_params
# Your code here

Need a hint?

Use the double asterisk ** to unpack the query_params dictionary as arguments.