session-2.md

Session 2: Learn how to use DynamoDB in your application

First, checkout session-2 branch, and deploy the ressources for session-2.

git checkout session-2-v2
cd backend
sls deploy

You can then open:

• Cloudformation interface to check out the ressources that have been created
• API Gateway interface to check out your API and your routes.
• AWS Lambda to check out your lambdas
• AWS Cloudwatch to check out their execution logs (log stream tab)

Create your first DynamoDb

If you haven't done it yet, in the front-end folder, copy-paste .env.development as .env.development.local and replace the httpApiId by yours (you can find it in API Gateway), and run yarn and yarn start.

Then, in the back-end folder, notice the new dynamodb.yml resource in the resources folder. Notice its TableName, AttributeNames and KeySchema.

To deploy it:

• Add the dynamo-db table as a ressource in the serverless.ts (end of file)
• Give your lambdas the IAM rights to Query, Put and Delete Items on this table by uncommenting the correct blocks in the serverless.ts.
• Deploy your stack
• Go to DynamoDB service to check your newly created table. Notice the default item attributes: partitionKey and sortKey from the yml ressource.

Now, it's your turn 💪

We will use the AWS SDK to interact with this table:

import { DynamoDB } from "aws-sdk";

Now, it's your turn:

• Open the AWS dynamoDb DocumentClient documentation to learn how to use its query, put and delete methods.
• Implement the get route to get Virus items instead of hard-coded ones.
• Create a post route that adds a Virus item to the db by adding a trigger to the createVirus lambda and call it in the frontend in the addVirus button onClick.
• Implement the delete route and call it in the frontend in viruses onClicks.

Pro tips:

• If you want to deploy only one function, use yarn deploy -f <your-function-name>. It is much faster (~10s) than deploying a stack (~30s) but will only deploy the function's code, not any config change in your serverless.ts.
• To call locally one function, use serverless invoke -f <your-function-name> --path path/to/mocked-event.json

Done ? Nice work ! Don't forget to kill your stack by running serverless remove in the backend folder !

To see final result, checkout the start of session 3.