Reading and writing items in batch in DynamoDB - AWS SDK for JavaScript
The scenarioPrerequisite tasksReading items in a batchWriting items in a batch

The AWS SDK for JavaScript V3 API Reference Guide describes in detail all the API operations for the AWS SDK for JavaScript version 3 (V3).

Reading and writing items in batch in DynamoDB

JavaScript code example that applies to Node.js execution

This Node.js code example shows:

  • How to read and write batches of items in a DynamoDB table.

The scenario

In this example, you use a series of Node.js modules to put a batch of items in a DynamoDB table and read a batch of items. The code uses the SDK for JavaScript to perform batch read and write operations using these methods of the DynamoDB client class:

Prerequisite tasks

To set up and run this example, first complete these tasks:

  • Set up the project environment to run these Node TypeScript examples, and install the required AWS SDK for JavaScript and third-party modules. Follow the instructions on GitHub.

  • Create a shared configurations file with your user credentials. For more information about providing a shared credentials file, see Shared config and credentials files in the AWS SDKs and Tools Reference Guide.

  • Create a DynamoDB table whose items you can access. For more information about creating a DynamoDB table, see Creating and using tables in DynamoDB.

Important

These examples use ECMAScript6 (ES6). This requires Node.js version 13.x or higher. To download and install the latest version of Node.js, see Node.js downloads..

However, if you prefer to use CommonJS syntax, please refer to JavaScript ES6/CommonJS syntax.

Note

For information about the data types used in these examples, see Supported data types and naming rules in Amazon DynamoDB.

Reading items in a batch

Create a Node.js module with the file name batch-get-item.js. Be sure to configure the SDK as previously shown, including downloading the required clients and packages. To access DynamoDB, create a DynamoDB client service object. Create a JSON object containing the parameters needed to get a batch of items, which in this example includes the name of one or more tables from which to read, the values of keys to read in each table, and the projection expression that specifies the attributes to return. Call the BatchGetItemCommand method of the DynamoDB service object.

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

const client = new DynamoDBClient({});

export const main = async () => {
  const command = new BatchGetItemCommand({
    RequestItems: {
      // Each key in this object is the name of a table. This example refers
      // to a PageAnalytics table.
      PageAnalytics: {
        // Each entry in Keys is an object that specifies a primary key.
        Keys: [
          {
            // "PageName" is the partition key (simple primary key).
            // "S" specifies a string as the data type for the value "Home".
            // For more information about data types,
            // see https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.NamingRulesDataTypes.html#HowItWorks.DataTypes and
            // https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/Programming.LowLevelAPI.html#Programming.LowLevelAPI.DataTypeDescriptors
            PageName: { S: "Home" },
          },
          {
            PageName: { S: "About" },
          },
        ],
        // Only return the "PageName" and "PageViews" attributes.
        ProjectionExpression: "PageName, PageViews",
      },
    },
  });

  const response = await client.send(command);
  console.log(response.Responses["PageAnalytics"]);
  return response;
};

To run the example, enter the following at the command prompt.

node batch-get-item.js

This example code can be found here on GitHub.

Writing items in a batch

Create a Node.js module with the file name batch-write-item.js. Be sure to configure the SDK as previously shown, including downloading the required clients and packages. To access DynamoDB, create a DynamoDB client service object. Create a JSON object containing the parameters needed to get a batch of items, which in this example includes the table into which you want to write items, the keys you want to write for each item, and the attributes along with their values. Call the BatchWriteItemCommand method of the DynamoDB service object.

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

const client = new DynamoDBClient({});

export const main = async () => {
  const command = new BatchWriteItemCommand({
    RequestItems: {
      // Each key in this object is the name of a table. This example refers
      // to a Coffees table.
      Coffees: [
        // Each entry in Coffees is an object that defines either a PutRequest or DeleteRequest.
        {
          // Each PutRequest object defines one item to be inserted into the table.
          PutRequest: {
            // The keys of Item are attribute names. Each attribute value is an object with a data type and value.
            // For more information about data types,
            // see https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.NamingRulesDataTypes.html#HowItWorks.DataTypes
            Item: {
              Name: { S: "Donkey Kick" },
              Process: { S: "Wet-Hulled" },
              Flavors: { SS: ["Earth", "Syrup", "Spice"] },
            },
          },
        },
        {
          PutRequest: {
            Item: {
              Name: { S: "Flora Ethiopia" },
              Process: { S: "Washed" },
              Flavors: { SS: ["Stone Fruit", "Toasted Almond", "Delicate"] },
            },
          },
        },
      ],
    },
  });

  const response = await client.send(command);
  console.log(response);
  return response;
};

To run the example, enter the following at the command prompt.

node batch-write-item.js

This example code can be found here on GitHub.