AWS SDK for JavaScript/Node.js in DynamoDB - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the DynamoDB client from AWS SDK.

DynamoDB

const { DynamoDBClient } = require('[1]');

Drag options to blanks, or click blank then click option'

A@aws-sdk/client-dynamodb

Baws-sdk

Caws-sdk-client

Daws-sdk-v3

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'aws-sdk' which is v2 and not modular.

Using incorrect package names like 'aws-sdk-client'.

The AWS SDK for JavaScript v3 modular packages require importing DynamoDBClient from '@aws-sdk/client-dynamodb'.

2fill in blank

medium

Complete the code to create a new DynamoDB client with region 'us-east-1'.

DynamoDB

const client = new DynamoDBClient({ region: '[1]' });

Drag options to blanks, or click blank then click option'

Aus-west-2

Beu-central-1

Cus-east-1

Dap-southeast-1

Attempts:

3 left

💡 Hint

Common Mistakes

Using a region that does not match the intended deployment.

Leaving the region undefined.

The region 'us-east-1' is specified as the AWS region for the DynamoDB client.

3fill in blank

hard

Fix the error in the code to put an item into DynamoDB using the client.

DynamoDB

const params = { TableName: 'Users', Item: { id: { S: '123' }, name: { S: 'Alice' } } };
await client.[1](new PutItemCommand(params));

Drag options to blanks, or click blank then click option'

Aput

Bsend

CputItemCommand

DputItem

Attempts:

3 left

💡 Hint

Common Mistakes

Calling 'putItem' directly on the client.

Using incorrect method names like 'put'.

In AWS SDK v3, you create a PutItemCommand and then call client.send(command). The client does not have a direct 'putItem' method.

4fill in blank

hard

Fill both blanks to import and create a PutItemCommand for DynamoDB.

DynamoDB

const { [1] } = require('@aws-sdk/client-dynamodb');
const command = new [2]({ TableName: 'Users', Item: { id: { S: '001' } } });

Drag options to blanks, or click blank then click option'

APutItemCommand

BDynamoDBClient

CPutCommand

DGetItemCommand

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing PutItemCommand with PutCommand or GetItemCommand.

Importing the client instead of the command.

The PutItemCommand is imported and instantiated to create a command for putting an item in DynamoDB.

5fill in blank

hard

Fill all three blanks to get an item from DynamoDB and extract the attribute 'name'.

DynamoDB

const { [1] } = require('@aws-sdk/client-dynamodb');
const client = new DynamoDBClient({ region: 'us-east-1' });
const command = new [2]({ TableName: 'Users', Key: { id: { S: '123' } } });
const response = await client.[3](command);
const userName = response.Item?.name?.S;

Drag options to blanks, or click blank then click option'

AGetItemCommand

BPutItemCommand

Csend

DgetItem

Attempts:

3 left

💡 Hint

Common Mistakes

Using PutItemCommand instead of GetItemCommand.

Calling 'getItem' method directly on the client.

To get an item, import and instantiate GetItemCommand, then call client.send(command) to execute it.

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