@aws-sdk/util-dynamodb

What is @aws-sdk/util-dynamodb?

The @aws-sdk/util-dynamodb package is part of the AWS SDK for JavaScript v3. It provides utility functions to serialize JavaScript objects into the DynamoDB record format and deserialize DynamoDB records into JavaScript objects. This is particularly useful when working with AWS DynamoDB, allowing developers to easily convert data between the formats used by their applications and the database.

What are @aws-sdk/util-dynamodb's main functionalities?

Marshall

Converts a JavaScript object into a DynamoDB record format. Useful for preparing data to be sent to DynamoDB.

const { marshall } = require('@aws-sdk/util-dynamodb');
const item = { id: 1, content: 'Hello World' };
const marshalledItem = marshall(item);
console.log(marshalledItem);

Unmarshall

Converts a DynamoDB record into a JavaScript object. This is useful when retrieving data from DynamoDB and using it within a JavaScript application.

const { unmarshall } = require('@aws-sdk/util-dynamodb');
const dynamoRecord = { id: { N: '1' }, content: { S: 'Hello World' } };
const item = unmarshall(dynamoRecord);
console.log(item);

ConvertEmptyValues

Allows the conversion of empty values (like null) to a specific DynamoDB type when marshalling. This helps in maintaining data consistency when storing in DynamoDB.

const { marshall } = require('@aws-sdk/util-dynamodb');
const item = { id: 1, content: null };
const options = { convertEmptyValues: true };
const marshalledItem = marshall(item, options);
console.log(marshalledItem);

Other packages similar to @aws-sdk/util-dynamodb

dynamodb-data-types

This package offers similar functionalities for attribute value wrapping and unwrapping for DynamoDB. It differs from @aws-sdk/util-dynamodb by being less integrated with the AWS SDK, potentially offering more flexibility in non-AWS SDK contexts.

README

@aws-sdk/util-dynamodb

This package provides utilities to be used with @aws-sdk/client-dynamodb

If you are looking for DynamoDB Document client, please check @aws-sdk/lib-dynamodb which automatically performs the necessary marshalling and unmarshalling.

Convert JavaScript object into DynamoDB Record

const { DynamoDB } = require("@aws-sdk/client-dynamodb");
const { marshall } = require("@aws-sdk/util-dynamodb");

const client = new DynamoDB(clientParams);
const params = {
  TableName: "Table",
  Item: marshall({
    HashKey: "hashKey",
    NumAttribute: 1,
    BoolAttribute: true,
    ListAttribute: [1, "two", false],
    MapAttribute: { foo: "bar" },
    NullAttribute: null,
  }),
};

await client.putItem(params);

Convert DynamoDB Record into JavaScript object

const { DynamoDB } = require("@aws-sdk/client-dynamodb");
const { marshall, unmarshall } = require("@aws-sdk/util-dynamodb");

const client = new DynamoDB(clientParams);
const params = {
  TableName: "Table",
  Key: marshall({
    HashKey: "hashKey",
  }),
};

const { Item } = await client.getItem(params);
unmarshall(Item);