In this article, we show how to add data to Amazon DynamoDB using the command line and Python. If you’re new to this product, see our DynamoDB introduction.

(This tutorial is part of our DynamoDB Guide. Use the right-hand menu to navigate.)

Set up DynamoDB First, download DynamoDB from Amazon. Run it locally to avoid paying subscription fees before you’re ready to push your project to the cloud. (Amazon says this is how you should use their database.)

Unzip DynamoDB then start it like this:

"java -Djava.library.path=./DynamoDBLocal_lib -jar DynamoDBLocal.jar -sharedDb"

Install the Amazon Boto3 API. Boto3 is Amazon’s Python interface to all their products, S3, DynamoDB, etc.

pip install boto3 Now, we will make up some data. This will be financial transactions. The key will be transNo. so create the expenses table. You need to install the AWS CLI client first.

Note that we use endpoint-url to indicate that we are using DynamoDB locally.

aws dynamodb create-table \ --table-name expenses \ --attribute-definitions AttributeName=transNo,AttributeType=N \ --key-schema AttributeName=transNo,KeyType=HASH \ --provisioned-throughput ReadCapacityUnits=5,WriteCapacityUnits=5 \ --endpoint-url localhost:8000 Open a Python shell and check that table exists.

import boto3

boto3.resource('dynamodb', endpoint_url='localhost:8000').Table('expenses') It should respond:

Add data from the command line Below we add a transaction with just a transaction number and a date. The N means that the transNo is a number and S means that the date is a string. (DynamoDB recognizes this ISO-8601 date format, so you can work with that attribute as if it were a date.)

Important note: When you use the put-item you have to put the data type (N, number, S, string, etc.) with the value in the JSON. You put numbers in quotes too. When you use Boto3 you don’t need to do --return-consumed-capacity TOTAL --endpoint-url localhost:8000 Add data with Python Boto3 The code below is self-explanatory, with these additional notes.

Dictionaries and JSON are also the same when using Python. So, construct JSON using dictionaries as it’s far simpler. The put_item method will accept a dictionary or JSON. Note that Boto3 does not accept floating point numbers. Instead use the Decimal For an amount, we pick a random integer randint() and multiply it by random(), since that’s less than 1 (financial amounts are probably usually greater than 1). The data we pass to DynamDB looks like this: