AWS SDK for JavaScript/Node.js in DynamoDB - Mini Project: Build & Apply

Basic DynamoDB Table Interaction with AWS SDK for JavaScript/Node.js

📖 Scenario: You are building a simple Node.js application that interacts with an AWS DynamoDB table to store and retrieve product information.

🎯 Goal: Learn how to set up a DynamoDB client, prepare data, and perform basic operations like putting an item and scanning the table using the AWS SDK for JavaScript.

📋 What You'll Learn

Create a JavaScript object representing a product with specific attributes.

Configure the DynamoDB client with the AWS SDK.

Write code to put the product item into the DynamoDB table.

Write code to scan the DynamoDB table to retrieve all items.

💡 Why This Matters

🌍 Real World

This project simulates a common task in cloud applications: storing and retrieving data from a managed NoSQL database service like DynamoDB.

💼 Career

Understanding how to use AWS SDK for JavaScript to interact with DynamoDB is essential for backend developers working with AWS cloud infrastructure.

1

Create a product object

Create a JavaScript constant called product with these exact key-value pairs: id set to "101", name set to "Notebook", and price set to 9.99.

DynamoDB

# Create a constant called product with id, name, and price
// Your code here

Hint

Use const product = { id: "101", name: "Notebook", price: 9.99 };

2

Configure DynamoDB client

Import DynamoDBClient from @aws-sdk/client-dynamodb and create a constant called client that initializes DynamoDBClient with the region set to "us-east-1".

DynamoDB

const product = { id: "101", name: "Notebook", price: 9.99 };
// Import DynamoDBClient and create client with region us-east-1
// Your code here

Hint

Use import { DynamoDBClient } from "@aws-sdk/client-dynamodb"; and const client = new DynamoDBClient({ region: "us-east-1" });

3

Put the product item into DynamoDB

Import PutItemCommand from @aws-sdk/client-dynamodb. Create a constant called putParams with TableName set to "Products" and Item mapping id, name, and price to DynamoDB attribute types (S for strings, N for numbers as strings). Then create a constant called putCommand using PutItemCommand with putParams.

DynamoDB

const product = { id: "101", name: "Notebook", price: 9.99 };

import { DynamoDBClient, PutItemCommand } from "@aws-sdk/client-dynamodb";

const client = new DynamoDBClient({ region: "us-east-1" });

// Create putParams with TableName 'Products' and Item mapping product keys to DynamoDB types
// Create putCommand using PutItemCommand with putParams
// Your code here

Hint

Remember to convert the number price to string for DynamoDB number type.

4

Scan the DynamoDB table

Import ScanCommand from @aws-sdk/client-dynamodb. Create a constant called scanParams with TableName set to "Products". Then create a constant called scanCommand using ScanCommand with scanParams.

DynamoDB

const product = { id: "101", name: "Notebook", price: 9.99 };

import { DynamoDBClient, PutItemCommand, ScanCommand } from "@aws-sdk/client-dynamodb";

const client = new DynamoDBClient({ region: "us-east-1" });

const putParams = {
  TableName: "Products",
  Item: {
    id: { S: product.id },
    name: { S: product.name },
    price: { N: product.price.toString() }
  }
};

const putCommand = new PutItemCommand(putParams);

// Create scanParams with TableName 'Products'
// Create scanCommand using ScanCommand with scanParams
// Your code here

Hint

Use ScanCommand with the table name to get all items.

Practice

1. What is the first step to interact with DynamoDB using the AWS SDK for JavaScript/Node.js?

easy

A. Create a DynamoDB client instance

B. Write a SQL query

C. Install a database driver

D. Open a database connection manually

Solution

1. Step 1: Understand AWS SDK usage

   To work with DynamoDB, you first create a client object that represents the service.

2. Step 2: Recognize the role of the client

   The client handles requests and responses to DynamoDB; no manual connection or SQL is needed.

3. Final Answer:

   Create a DynamoDB client instance -> Option A

4. Quick Check:

   Client creation = First step [OK]

Hint: Always start by creating the service client [OK]

Common Mistakes:

• Trying to write SQL queries for DynamoDB
• Assuming manual connection is needed
• Skipping client creation

2. Which of the following is the correct way to import the DynamoDB client from AWS SDK v3 in Node.js?

easy

A. const DynamoDBClient = require('@aws-sdk/client-dynamodb');

B. const { DynamoDBClient } = require('aws-sdk');

C. import { DynamoDBClient } from '@aws-sdk/client-dynamodb';

D. import DynamoDBClient from 'aws-sdk';

Solution

1. Step 1: Identify AWS SDK v3 import style

   AWS SDK v3 uses ES modules and named imports from '@aws-sdk/client-dynamodb'.

2. Step 2: Match correct syntax

   import { DynamoDBClient } from '@aws-sdk/client-dynamodb'; uses ES module import with correct package and named import syntax.

3. Final Answer:

   import { DynamoDBClient } from '@aws-sdk/client-dynamodb'; -> Option C

4. Quick Check:

   ES module named import = import { DynamoDBClient } from '@aws-sdk/client-dynamodb'; [OK]

Hint: Use ES module imports from '@aws-sdk/client-dynamodb' [OK]

Common Mistakes:

• Using old AWS SDK v2 import style
• Using default import instead of named import
• Mixing require and import syntax

3. Given the following code snippet, what will be logged if the item exists in the DynamoDB table?

import { DynamoDBClient, GetItemCommand } from '@aws-sdk/client-dynamodb';
const client = new DynamoDBClient({ region: 'us-east-1' });

async function getItem() {
  const command = new GetItemCommand({
    TableName: 'Users',
    Key: { 'UserId': { S: '123' } }
  });
  const response = await client.send(command);
  console.log(response.Item);
}
getItem();

medium

A. Undefined because no item exists

B. An empty object {}

C. An error is thrown due to missing parameters

D. The item object with attributes if found

Solution

1. Step 1: Understand GetItemCommand behavior

   GetItemCommand returns an object with an Item property if the item exists.

2. Step 2: Analyze console.log output

   Logging response.Item will show the item's attributes as an object if found.

3. Final Answer:

   The item object with attributes if found -> Option D

4. Quick Check:

   response.Item = item object [OK]

Hint: GetItemCommand returns Item if found, else undefined [OK]

Common Mistakes:

• Expecting an error when item is missing
• Assuming response itself is the item
• Confusing empty object with undefined

4. What is wrong with the following code snippet that tries to put an item into DynamoDB?

import { DynamoDBClient, PutItemCommand } from '@aws-sdk/client-dynamodb';
const client = new DynamoDBClient({ region: 'us-east-1' });

async function putItem() {
  const command = new PutItemCommand({
    TableName: 'Users',
    Item: { UserId: '123', Name: 'Alice' }
  });
  await client.send(command);
}
putItem();

medium

A. TableName should be lowercase

B. Item attributes must be wrapped with DynamoDB data types like { S: 'value' }

C. PutItemCommand does not exist in AWS SDK

D. Missing await before client.send

Solution

1. Step 1: Check Item attribute format

   DynamoDB expects attribute values wrapped in type descriptors like { S: 'string' }.

2. Step 2: Identify the error cause

   Passing plain strings without type wrappers causes validation errors.

3. Final Answer:

   Item attributes must be wrapped with DynamoDB data types like { S: 'value' } -> Option B

4. Quick Check:

   Attribute values need type wrappers [OK]

Hint: Always wrap attribute values with DynamoDB types (S, N, etc.) [OK]

Common Mistakes:

• Passing plain strings instead of typed attributes
• Assuming table names are case-insensitive
• Forgetting to await async calls

5. You want to update a user's email in DynamoDB using AWS SDK for JavaScript/Node.js. Which approach correctly updates only the email attribute without overwriting the entire item?

const command = new UpdateItemCommand({
  TableName: 'Users',
  Key: { UserId: { S: '123' } },
  UpdateExpression: 'SET Email = :email',
  ExpressionAttributeValues: { ':email': { S: '[e-mail]' } }
});
await client.send(command);

hard

A. This code correctly updates only the Email attribute

B. UpdateExpression should be 'ADD Email :email' to update

C. You must use PutItemCommand to update attributes

D. ExpressionAttributeValues keys should not start with ':'

Solution

1. Step 1: Understand UpdateItemCommand usage

   UpdateExpression with 'SET' updates specified attributes without replacing the whole item.

2. Step 2: Verify ExpressionAttributeValues syntax

   Keys start with ':' and values use DynamoDB types, matching the expression.

3. Step 3: Confirm no overwrite occurs

   Using UpdateItemCommand with SET updates only Email, preserving other attributes.

4. Final Answer:

   This code correctly updates only the Email attribute -> Option A

5. Quick Check:

   UpdateExpression SET = partial update [OK]

Hint: Use UpdateItemCommand with SET to update attributes safely [OK]

Common Mistakes:

• Using PutItemCommand which overwrites entire item
• Using ADD instead of SET for attribute update
• Removing ':' prefix in ExpressionAttributeValues keys