DynamoDB Document Client

Document Client Overview

Document Client lets you structure DynamoDB work so it stays readable, testable, and easy to scale. Instead of ad-hoc code, you follow a clear pattern that other developers can recognise immediately.

The key is to keep document client focused and predictable. Start from the minimal example here, then layer in only the complexity your feature actually needs.

import { DynamoDBClient } from '@aws-sdk/client-dynamodb';
import { DynamoDBDocumentClient, GetCommand, PutCommand } from '@aws-sdk/lib-dynamodb';

const client = new DynamoDBClient({});
const docClient = DynamoDBDocumentClient.from(client);

// reuse docClient across the module for efficient, typed access
await docClient.send(new PutCommand({ TableName: 'Orders', Item: { pk: '1' } }));

The DynamoDBDocumentClient maps plain JavaScript objects to DynamoDB item format for you.

Document Client Example

import { DynamoDBClient } from '@aws-sdk/client-dynamodb';
import { DynamoDBDocumentClient } from '@aws-sdk/lib-dynamodb';

const docClient = DynamoDBDocumentClient.from(new DynamoDBClient({}));
// docClient.send(new PutCommand(...)) etc.

• Start from a minimal Document Client example and grow it only as needed.
• Keep configuration explicit so Document Client behaves the same in every environment.
• Name things clearly so teammates understand your Document Client at a glance.
• Add tests around Document Client early to lock in expected behaviour.

Amazon DynamoDB Cheatsheet

Handy DynamoDB (AWS SDK v3) reference related to document client.

How Document Client Works in DynamoDB

Document Client builds on DynamoDB's key-value and document model, where every item lives in a partition chosen by its partition key and is optionally ordered by a sort key.

The DynamoDBDocumentClient maps plain JavaScript objects to DynamoDB item format for you.

• Design access patterns first, then model keys around them.
• Prefer Query over Scan for predictable performance.
• Use expressions to read and write only what you need.
• Keep items small and avoid hot partitions.

Practical Guidance for Document Client

In production, document client should be cost-aware and resilient. Right-size capacity, handle throttling with retries, and lean on indexes to support your query patterns.

Common Mistakes

• Skipping error handling and edge cases when wiring up document client.
• Leaving document client untested, so regressions slip into production.
• Over-engineering document client before you actually need the extra flexibility.
• Ignoring documentation, which makes document client hard for the next developer to change.

Key Takeaways

• Document Client is a core part of working effectively with DynamoDB.
• Start small and keep document client focused on a single responsibility.
• Apply consistent patterns so document client scales across your project.
• Test and document document client to keep it maintainable over time.