A Beginner’s Guide to CRUD Operations in DynamoDB

A Beginner’s Guide to CRUD Operations in DynamoDB

Objective

The objective of this article is to help you understand CRUD Operations in DynamoDB. In this article, you will learn about to create a DynamoDB table using the CloudFormation template and perform the create, read, update, and delete data using the AWS CLI tool.

Prerequisites

• An AWS account with permissions to access DynamoDB
• Basic knowledge of NoSQL database – DynamoDB

Step-1: Create a DynamoDB table using CloudFormation

Create a new file called “create-dynamo-db-cf.template” and paste the following code to create a DynamoDB Table.

{
    "AWSTemplateFormatVersion": "2010-09-09",
     "Parameters": {
        "TableName": {
            "Type": "String",
            "Default" : "CustomerTable",
            "Description": "Name of the DynamoDB table to be created"
        },
        "ReadCapacity": {
            "Type": "Number",
            "Default" : 5,
            "Description": "The maximum number of strongly consistent reads per second"
        },
        "WriteCapacity": {
            "Type": "Number",
            "Default" : 5,
            "Description": "The maximum number of writes per second"
        },
        "CapacityMode": {
            "Type": "String",
            "Description": "The capacity mode to use for the DynamoDB table",
            "AllowedValues": [
                "PAY_PER_REQUEST",
                "PROVISIONED"
            ]
        }
    },
    "Resources": {
        "DynamoDBTable": {
            "Type": "AWS::DynamoDB::Table",
            "Properties": {
                "AttributeDefinitions": [
                    {
                        "AttributeName": "Id",
                        "AttributeType": "N"
                    }
                ],
                "KeySchema": [
                    {
                        "AttributeName": "Id",
                        "KeyType": "HASH"
                    }
                ],
                "BillingMode": {"Ref" : "CapacityMode"},
                "ProvisionedThroughput": {
                    "ReadCapacityUnits": {"Ref" : "ReadCapacity"},
                    "WriteCapacityUnits": {"Ref" : "WriteCapacity" }
                },
                "TableName": {"Ref" : "TableName"}
            }
        }
    },   
    "Outputs": {
        "TableName": {
            "Description": "Name of the DynamoDB table",
            "Value": {
                "Ref": "DynamoDBTable"
            }
        }
    }
}

This cloud formation template is used to create a DynamoDB table with the following parameters:

• AWSTemplateFormatVersion: specifies the format version of the template
• Parameters: declares input parameters that can be passed into the template when it is run
  • TableName: specifies the name of the DynamoDB table to be created
  • ReadCapacity: specifies the maximum number of strongly consistent reads per second for the DynamoDB table
  • WriteCapacity: specifies the maximum number of writes per second for the DynamoDB table
  • CapacityMode: specifies the capacity mode to use for the DynamoDB table, with the allowed values of PAY_PER_REQUEST or PROVISIONED
• Resources: declares the resources that are created by the template, in this case, a DynamoDB table with the specified properties
  • DynamoDBTable: specifies the type of resource to create – AWS::DynamoDB::Table
  • AttributeDefinitions: specifies the attributes that define the key schema of the DynamoDB table
  • KeySchema: specifies the key attributes of the DynamoDB table
  • BillingMode: specifies the billing mode for the DynamoDB table using the value of the CapacityMode parameter
  • ProvisionedThroughput: specifies the provisioned throughput for the DynamoDB table using the values of the ReadCapacity and WriteCapacity parameters
• Outputs: declares the output values that can be returned by the template when it is run.

Step-2: Deploy cloud formation template from AWS console

• Login to your AWS Console and navigate to the “CloudFormation” service
• Click on the “Create stack” button to start the cloud formation creation process.
• Upload your created template file “create-dynamo-db-cf.template”, Click on “Next”
  
• Specify the stack details, Click on “Next”, “NEXT” and “Submit”. Wait until stack creation is complete.
  
• Using AWS Console search, navigate to the “DynamoDB” service. Verify that the DynamoDB table gets created by the cloud formation template.
  

Step-3: Create, Read, Update, and Delete operations using AWS CLI command

Here are example AWS CLI commands for CRUD operations on a DynamoDB table named “CustomerTable” with a primary key “Id” for the model

Customer
{ 
    "Id": int, 
    "Name": "string", 
     "Email": "string"
    "Address": "string", 
}

Following commands output based on Windows environment and AWS CLI2.

Create a new item – A new customer entry in DynamoDB table

aws dynamodb put-item --table-name CustomerTable --item "{\"Id\":{\"N\": \"123\"},\"Name\":{\"S\":\"John Wick\"},\"Email\":{\"S\": \"johnwick@example.com\"}, \"Address\": {\"S\": \"123 Main St\"}}"

Read item: Get the customer details with an Id of 123

aws dynamodb get-item --table-name CustomerTable --key "{ \"Id\": {\"N\": \"123\"} }"

Update item: update existing customer details with Id of 123

aws dynamodb update-item --table-name CustomerTable --key "{\"Id\": {\"N\": \"123\"}}" --update-expression "SET #name = :name, #email = :email, #address = :address" --expression-attribute-names "{\"#name\": \"Name\", \"#email\": \"Email\", \"#address\": \"Address\"}" --expression-attribute-values "{\":name\": {\"S\": \"James\"}, \":email\": {\"S\": \"James@example.com\"}, \":address\": {\"S\": \"456 Main St\"}}"

Delete item: Delete customer details from table with Id of 123

aws dynamodb delete-item --table-name CustomerTable --key "{ \"Id\": {\"N\": \"123\"} }"

Note: Delete the cloud formation stack “create-dynamo-db-cf.template” to delete DynamoDB.