Expression attribute values in DynamoDB - Mini Project: Build & Apply

Using Expression Attribute Values in DynamoDB Queries

📖 Scenario: You are managing a DynamoDB table that stores information about books in a library. You want to query the table to find books by a specific author using expression attribute values to safely insert the author name into the query.

🎯 Goal: Build a DynamoDB query using expression attribute values to find all books by the author 'J.K. Rowling'.

📋 What You'll Learn

Create a dictionary called expression_attribute_values with the key ':author' and value {"S": "J.K. Rowling"}.

Create a variable called key_condition_expression with the value 'Author = :author'.

Write a query dictionary called query_params that includes TableName, KeyConditionExpression, and ExpressionAttributeValues using the variables above.

Add a final key ReturnConsumedCapacity with the value 'TOTAL' to the query_params dictionary.

💡 Why This Matters

🌍 Real World

Using expression attribute values helps prevent injection attacks and errors when querying DynamoDB tables in real applications like library management systems.

💼 Career

Understanding how to safely build DynamoDB queries with expression attribute values is essential for backend developers and cloud engineers working with AWS databases.

1

Create expression attribute values dictionary

Create a dictionary called expression_attribute_values with one key ':author' and its value as a dictionary with key 'S' and value 'J.K. Rowling'.

DynamoDB

# Create expression_attribute_values dictionary
# Your code here

Need a hint?

Use a dictionary with the key ':author' and the value as another dictionary with key 'S' and value 'J.K. Rowling'.

2

Create key condition expression string

Create a variable called key_condition_expression and set it to the string 'Author = :author'.

DynamoDB

expression_attribute_values = {':author': {'S': 'J.K. Rowling'}}
# Create key_condition_expression string
# Your code here

Need a hint?

Assign the string 'Author = :author' to the variable key_condition_expression.

3

Create query parameters dictionary

Create a dictionary called query_params with keys 'TableName' set to 'Books', 'KeyConditionExpression' set to key_condition_expression, and 'ExpressionAttributeValues' set to expression_attribute_values.

DynamoDB

expression_attribute_values = {':author': {'S': 'J.K. Rowling'}}
key_condition_expression = 'Author = :author'
# Create query_params dictionary
# Your code here

Need a hint?

Use the variables key_condition_expression and expression_attribute_values as values in the query_params dictionary.

4

Add ReturnConsumedCapacity to query parameters

Add a key 'ReturnConsumedCapacity' with the value 'TOTAL' to the query_params dictionary.

DynamoDB

expression_attribute_values = {':author': {'S': 'J.K. Rowling'}}
key_condition_expression = 'Author = :author'
query_params = {
    'TableName': 'Books',
    'KeyConditionExpression': key_condition_expression,
    'ExpressionAttributeValues': expression_attribute_values
}
# Add ReturnConsumedCapacity key to query_params
# Your code here

Need a hint?

Add the key 'ReturnConsumedCapacity' with value 'TOTAL' inside the query_params dictionary.