One-to-many relationship patterns in DynamoDB - Mini Project: Build & Apply

One-to-many relationship patterns in DynamoDB

📖 Scenario: You are building a simple online bookstore database using DynamoDB. Each author can write many books, so you need to model this one-to-many relationship efficiently.

🎯 Goal: Create a DynamoDB table structure and queries to store authors and their books using a one-to-many relationship pattern.

📋 What You'll Learn

Create a DynamoDB table with a partition key and sort key to model authors and books

Add a configuration variable for the table name

Write a query to get all books by a specific author

Add a final configuration to enable consistent reads

💡 Why This Matters

🌍 Real World

Modeling one-to-many relationships in DynamoDB is common for applications like online stores, social media, and content management systems where one entity relates to many others.

💼 Career

Understanding how to design DynamoDB tables with partition and sort keys and how to query them efficiently is essential for backend developers and cloud engineers working with AWS.

1

Create DynamoDB table with partition and sort keys

Create a DynamoDB table called Bookstore with AuthorID as the partition key and BookID as the sort key.

DynamoDB

# Define the DynamoDB table with partition key AuthorID and sort key BookID
# Your code here

Need a hint?

Use KeySchema with HASH for partition key and RANGE for sort key.

2

Add table name configuration variable

Create a variable called table_name and set it to the string 'Bookstore'.

DynamoDB

Bookstore = {
    'TableName': 'Bookstore',
    'KeySchema': [
        {'AttributeName': 'AuthorID', 'KeyType': 'HASH'},
        {'AttributeName': 'BookID', 'KeyType': 'RANGE'}
    ],
    'AttributeDefinitions': [
        {'AttributeName': 'AuthorID', 'AttributeType': 'S'},
        {'AttributeName': 'BookID', 'AttributeType': 'S'}
    ],
    'BillingMode': 'PAY_PER_REQUEST'
}

# Your code here

Need a hint?

Just assign the string 'Bookstore' to table_name.

3

Write query to get all books by an author

Write a query dictionary called query_books_by_author that uses table_name and a key condition expression to get all books where AuthorID equals author_id. Use Key('AuthorID').eq(author_id) for the key condition expression.

DynamoDB

Bookstore = {
    'TableName': 'Bookstore',
    'KeySchema': [
        {'AttributeName': 'AuthorID', 'KeyType': 'HASH'},
        {'AttributeName': 'BookID', 'KeyType': 'RANGE'}
    ],
    'AttributeDefinitions': [
        {'AttributeName': 'AuthorID', 'AttributeType': 'S'},
        {'AttributeName': 'BookID', 'AttributeType': 'S'}
    ],
    'BillingMode': 'PAY_PER_REQUEST'
}

table_name = 'Bookstore'

# Your code here

Need a hint?

Use KeyConditionExpression with Key('AuthorID').eq(author_id).

4

Enable consistent reads in the query

Add ConsistentRead=True to the query_books_by_author dictionary to enable strongly consistent reads.

DynamoDB

from boto3.dynamodb.conditions import Key

Bookstore = {
    'TableName': 'Bookstore',
    'KeySchema': [
        {'AttributeName': 'AuthorID', 'KeyType': 'HASH'},
        {'AttributeName': 'BookID', 'KeyType': 'RANGE'}
    ],
    'AttributeDefinitions': [
        {'AttributeName': 'AuthorID', 'AttributeType': 'S'},
        {'AttributeName': 'BookID', 'AttributeType': 'S'}
    ],
    'BillingMode': 'PAY_PER_REQUEST'
}

table_name = 'Bookstore'

author_id = 'author123'

query_books_by_author = {
    'TableName': table_name,
    'KeyConditionExpression': Key('AuthorID').eq(author_id)
}

# Your code here

Need a hint?

Add the key 'ConsistentRead' with value True inside the query dictionary.