In this example we’ll look at how to create an AppSync GraphQL API on AWS using SST. We’ll be allowing our users to get, create, update, delete, and list notes.

We’ll be using SST’s Live Lambda Development. It allows you to make changes and test AppSync locally without having to redeploy.

Here is a video of it in action.

Requirements

Create an SST app

Let’s start by creating an SST app.

$ npx create-sst@latest --template=minimal/typescript-starter graphql-appsync
$ cd graphql-appsync
$ npm install

By default, our app will be deployed to an environment (or stage) called dev and the us-east-1 AWS region. This can be changed in the sst.json in your project root.

{
  "name": "graphql-appsync",
  "region": "us-east-1",
  "main": "stacks/index.ts"
}

Project layout

An SST app is made up of two parts.

  1. stacks/ — App Infrastructure

    The code that describes the infrastructure of your serverless app is placed in the stacks/ directory of your project. SST uses AWS CDK, to create the infrastructure.

  2. services/ — App Code

    The code that’s run when your API is invoked is placed in the services/ directory of your project.

Setting up our infrastructure

Let’s start by defining our AppSync API.

Replace the stacks/MyStack.ts with the following.

import { StackContext, Table, AppSyncApi } from "@serverless-stack/resources";

export function MyStack({ stack }: StackContext) {
  // Create a notes table
  const notesTable = new Table(stack, "Notes", {
    fields: {
      id: "string",
    },
    primaryIndex: { partitionKey: "id" },
  });

  // Create the AppSync GraphQL API
  const api = new AppSyncApi(stack, "AppSyncApi", {
    schema: "services/graphql/schema.graphql",
    defaults: {
      function: {
        bind: [notesTable],
      },
    },
    dataSources: {
      notes: "functions/lambda.handler",
    },
    resolvers: {
      "Query    listNotes": "notes",
      "Query    getNoteById": "notes",
      "Mutation createNote": "notes",
      "Mutation updateNote": "notes",
      "Mutation deleteNote": "notes",
    },
  });

  // Show the AppSync API Id and API Key in the output
  stack.addOutputs({
    ApiId: api.apiId,
    ApiKey: api.cdk.graphqlApi.apiKey,
    APiUrl: api.url,
  });
}

We are creating an AppSync GraphQL API here using the AppSyncApi construct. We are also creating a DynamoDB table using the Table construct. It’ll store the notes we’ll be creating with our GraphQL API.

Finally, we bind our table to our API.

Define the GraphQL schema

Add the following to services/graphql/schema.graphql.

type Note {
  id: ID!
  content: String!
}

input NoteInput {
  id: ID!
  content: String!
}

input UpdateNoteInput {
  id: ID!
  content: String
}

type Query {
  listNotes: [Note]
  getNoteById(noteId: String!): Note
}

type Mutation {
  createNote(note: NoteInput!): Note
  deleteNote(noteId: String!): String
  updateNote(note: UpdateNoteInput!): Note
}

Let’s also add a type for our note object.

Add the following to a new file in services/Note.ts.

type Note = {
  id: string;
  content: string;
};

export default Note;

Adding the function handler

To start with, let’s create the Lambda function that’ll be our AppSync data source.

Replace services/functions/lambda.ts with the following.

import Note from "./Note";
import listNotes from "./listNotes";
import createNote from "./createNote";
import updateNote from "./updateNote";
import deleteNote from "./deleteNote";
import getNoteById from "./getNoteById";

type AppSyncEvent = {
  info: {
    fieldName: string;
  };
  arguments: {
    note: Note;
    noteId: string;
  };
};

export async function handler(
  event: AppSyncEvent
): Promise<Record<string, unknown>[] | Note | string | null | undefined> {
  switch (event.info.fieldName) {
    case "listNotes":
      return await listNotes();
    case "createNote":
      return await createNote(event.arguments.note);
    case "updateNote":
      return await updateNote(event.arguments.note);
    case "deleteNote":
      return await deleteNote(event.arguments.noteId);
    case "getNoteById":
      return await getNoteById(event.arguments.noteId);
    default:
      return null;
  }
}

Now let’s implement our resolvers.

Create a note

Starting with the one that’ll create a note.

Add a file to services/createNote.ts.

import { DynamoDB } from "aws-sdk";
import { Table } from "@serverless-stack/node/table";
import Note from "./Note";

const dynamoDb = new DynamoDB.DocumentClient();

export default async function createNote(note: Note): Promise<Note> {
  const params = {
    Item: note as Record<string, unknown>,
    TableName: Table.Notes.tableName,
  };

  await dynamoDb.put(params).promise();

  return note;
}

Here, we are storing the given note in our DynamoDB table.

Let’s install the aws-sdk package in the services/ folder package that we are using.

$ npm install aws-sdk

Read the list of notes

Next, let’s write the function that’ll fetch all our notes.

Add the following to services/listNotes.ts.

import { DynamoDB } from "aws-sdk";
import { Table } from "@serverless-stack/node/table";

const dynamoDb = new DynamoDB.DocumentClient();

export default async function listNotes(): Promise<
  Record<string, unknown>[] | undefined
> {
  const params = {
    TableName: Table.Notes.tableName,
  };

  const data = await dynamoDb.scan(params).promise();

  return data.Items;
}

Here we are getting all the notes from our table.

Read a specific note

We’ll do something similar for the function that gets a single note.

Create a services/getNoteById.ts.

import { DynamoDB } from "aws-sdk";
import { Table } from "@serverless-stack/node/table";
import Note from "./Note";

const dynamoDb = new DynamoDB.DocumentClient();

export default async function getNoteById(
  noteId: string
): Promise<Note | undefined> {
  const params = {
    Key: { id: noteId },
    TableName: Table.Notes.tableName,
  };

  const { Item } = await dynamoDb.get(params).promise();

  return Item as Note;
}

We are getting the note with the id that’s passed in.

Update a note

Now let’s update our notes.

Add a services/updateNote.ts with:

import { DynamoDB } from "aws-sdk";
import { Table } from "@serverless-stack/node/table";
import Note from "./Note";

const dynamoDb = new DynamoDB.DocumentClient();

export default async function updateNote(note: Note): Promise<Note> {
  const params = {
    Key: { id: note.id },
    ReturnValues: "UPDATED_NEW",
    UpdateExpression: "SET content = :content",
    TableName: Table.Notes.tableName,
    ExpressionAttributeValues: { ":content": note.content },
  };

  await dynamoDb.update(params).promise();

  return note as Note;
}

We are using the id and the content of the note that’s passed in to update a note.

Delete a note

To complete all the operations, let’s delete the note.

Add this to services/deleteNote.ts.

import { DynamoDB } from "aws-sdk";
import { Table } from "@serverless-stack/node/table";

const dynamoDb = new DynamoDB.DocumentClient();

export default async function deleteNote(noteId: string): Promise<string> {
  const params = {
    Key: { id: noteId },
    TableName: Table.Notes.tableName,
  };

  // await dynamoDb.delete(params).promise();

  return noteId;
}

Note that, we are purposely disabling the delete query for now. We’ll come back to this later.

Let’s install the aws-sdk package in the services/ folder.

$ npm install aws-sdk

Let’s test what we’ve created so far!

Starting your dev environment

SST features a Live Lambda Development environment that allows you to work on your serverless apps live.

$ npm start

The first time you run this command it’ll take a couple of minutes to deploy your app and a debug stack to power the Live Lambda Development environment.

===============
 Deploying app
===============

Preparing your SST app
Transpiling source
Linting source
Deploying stacks
dev-graphql-appsync-my-stack: deploying...

 ✅  dev-graphql-appsync-my-stack


Stack dev-graphql-appsync-my-stack
  Status: deployed
  Outputs:
    ApiId: lk2fgfxsizdstfb24c4y4dnad4
    ApiKey: da2-3oknz5th4nbj5oobjz4jwid62q
    ApiUrl: https://2ngraxbyo5cwdpsk47wgn3oafu.appsync-api.us-east-1.amazonaws.com/graphql

The ApiId is the Id of the AppSync API we just created, the ApiKey is the API key of our AppSync API and ApiUrl is the AppSync API URL.

Let’s test our endpoint with the SST Console. The SST Console is a web based dashboard to manage your SST apps. Learn more about it in our docs.

Go to the GraphQL tab and you should see the GraphQL Playground in action.

Note, The GraphQL explorer lets you query GraphQL endpoints created with the GraphQLApi and AppSyncApi constructs in your app.

Let’s start by creating a note. Paste the below mutation in the left part of the playground.

mutation createNote {
  createNote(note: { id: "001", content: "My note" }) {
    id
    content
  }
}

GraphQL console create note

Also let’s go to the DynamoDB tab in the SST Console and check that the value has been created in the table.

Note, The DynamoDB explorer allows you to query the DynamoDB tables in the Table constructs in your app. You can scan the table, query specific keys, create and edit items.

DynamoDB explorer create note

And let’s get the note we just created by running this query instead.

query getNoteById {
  getNoteById(noteId: "001") {
    id
    content
  }
}

GraphQL console get note

Let’s test our update mutation by running:

mutation updateNote {
  updateNote(note: { id: "001", content: "My updated note" }) {
    id
    content
  }
}

GraphQL console update note

Now let’s try deleting our note.

mutation deleteNote {
  deleteNote(noteId: "001")
}

GraphQL console delete note

Let’s test if the delete worked by getting all the notes.

query listNotes {
  listNotes {
    id
    content
  }
}

GraphQL console list notes

You’ll notice a couple of things. Firstly, the note we created is still there. This is because our deleteNote method isn’t actually running our query. Secondly, our note should have the updated content from our previous query.

Making changes

Let’s fix our services/deleteNote.ts by un-commenting the query.

await dynamoDb.delete(params).promise();

If you head back to the query editor and run the delete mutation again.

mutation deleteNote {
  deleteNote(noteId: "001")
}

GraphQL console delete note after change

And running the list query should now show that the note has been removed!

query listNotes {
  listNotes {
    id
    content
  }
}

GraphQL console list notes after change

Notice we didn’t need to redeploy our app to see the change.

Deploying your API

Now that our API is tested, let’s deploy it to production. You’ll recall that we were using a dev environment, the one specified in our sst.json. However, we are going to deploy it to a different environment. This ensures that the next time we are developing locally, it doesn’t break the API for our users.

Run the following in your terminal.

$ npx sst deploy --stage prod

Cleaning up

Finally, you can remove the resources created in this example using the following commands.

$ npx sst remove
$ npx sst remove --stage prod

Conclusion

And that’s it! You’ve got a brand new serverless GraphQL API built with AppSync. A local development environment, to test and make changes. And it’s deployed to production as well, so you can share it with your users. Check out the repo below for the code we used in this example. And leave a comment if you have any questions!