Add an API to Get a Note

Now that we created a note and saved it to our database, let’s add an API to retrieve a note given its id.

Add the Function

Create a new file in packages/functions/src/get.ts with the following:

import { Resource } from "sst";
import { Util } from "@notes/core/util";
import { DynamoDBClient } from "@aws-sdk/client-dynamodb";
import { GetCommand, DynamoDBDocumentClient } from "@aws-sdk/lib-dynamodb";

const dynamoDb = DynamoDBDocumentClient.from(new DynamoDBClient({}));

export const main = Util.handler(async (event) => {
  const params = {
    TableName: Resource.Notes.name,
    // 'Key' defines the partition key and sort key of
    // the item to be retrieved
    Key: {
      userId: "123", // The id of the author
      noteId: event?.pathParameters?.id, // The id of the note from the path
    },
  };

  const result = await dynamoDb.send(new GetCommand(params));
  if (!result.Item) {
    throw new Error("Item not found.");
  }

  // Return the retrieved item
  return JSON.stringify(result.Item);
});

This follows exactly the same structure as our previous create.ts function. The major difference here is that we are doing a GetCommand(params) to get a note object given the userId (still hardcoded) and noteId that’s passed in through the request.

Add the route

Let’s add a new route for the get note API.

Add the following below the POST /notes route in infra/api.ts.

api.route("GET /notes/{id}", "packages/functions/src/get.main");

Deploy Our Changes

If you switch over to your terminal, you will notice that your changes are being deployed.

You should see that the new API has been deployed and given an AWS generated subdomain that looks something like https://<generated_subdomain>.execute-api.<aws_region>.amazonaws.com.

+  Complete
   Api: https://5bv7x0iuga.execute-api.us-east-1.amazonaws.com

Test the API

Let’s test the get notes API. In the previous chapter we tested our create note API. It should’ve returned the new note’s id as the noteId.

Run the following in your terminal. Remember to replace the generated subdomain and region with the values generated earlier.

$ curl https://<generated_subdomain>.execute-api.<aws_region>.amazonaws.com/notes/<NOTE_ID>

Make sure to replace the endpoint URL with your ApiEndpoint value and the at the end of the URL with the `noteId` that was created previously.

Since we are making a simple GET request, we could also go to this URL directly in your browser.

The response should look something like this.

{"attachment":"hello.jpg","content":"Hello World","createdAt":1629336889054,"noteId":"a46b7fe0-008d-11ec-a6d5-a1d39a077784","userId":"123"}

Next, let’s create an API to list all the notes a user has.