Todo app AppSync API with CDK

appsync-cdk-stack.ts

import * as cdk from '@aws-cdk/core';
import { CfnApiKey, PrimaryKey, Values, GraphQLApi, MappingTemplate, FieldLogLevel, AttributeValues } from '@aws-cdk/aws-appsync'
import { AttributeType, BillingMode, Table } from '@aws-cdk/aws-dynamodb';
import * as lambda from '@aws-cdk/aws-lambda'
import { join } from 'path';

export class AppsyncCdkStack extends cdk.Stack {
  constructor(scope: cdk.Construct, id: string, props?: cdk.StackProps) {
    super(scope, id, props);

    const api = new GraphQLApi(this, 'Api', {
      name: `cdkapi`,
      logConfig: {
        fieldLogLevel: FieldLogLevel.ALL,
      },
      schemaDefinitionFile: join('__dirname', '/../', 'graphql/schema.graphql'),
    });
    
    const apiKey = new CfnApiKey(this, 'public-api-key', {
      apiId: api.apiId
    });


    const todoTable = new Table(this, 'MainTodoTable', {
      billingMode: BillingMode.PAY_PER_REQUEST,
      partitionKey: {
        name: 'id',
        type: AttributeType.STRING,
      },
    });

    const todoDS = api.addDynamoDbDataSource('Todo', 'The todo data source', todoTable);

    // Query Resolver to get all Todos
    todoDS.createResolver({
      typeName: 'Query',
      fieldName: 'listTodos',
      requestMappingTemplate: MappingTemplate.fromString(`
        #set( $limit = $util.defaultIfNull($context.args.limit, 100) )
	#set( $ListRequest = {
	  "version": "2018-05-29",
	  "limit": $limit
	} )

	#if( $context.args.nextToken )
	  #set( $ListRequest.nextToken = $context.args.nextToken )
	#end

	$util.qr($ListRequest.put("operation", "Scan"))
	$util.toJson($ListRequest)
      `),
      responseMappingTemplate: MappingTemplate.fromString(`
      #if( $ctx.error)
        $util.error($ctx.error.message, $ctx.error.type)
      #else
        $util.toJson($ctx.result)
      #end
      `)
    });

    // Query Resolver to get an individual Todo by id
    todoDS.createResolver({
      typeName: 'Query',
      fieldName: 'getTodo',
      requestMappingTemplate: MappingTemplate.dynamoDbGetItem('id', 'id'),
      responseMappingTemplate: MappingTemplate.dynamoDbResultItem(),
    });

    // Mutation Resolver for creating a new Todo
    todoDS.createResolver({
      typeName: 'Mutation',
      fieldName: 'createTodo',
      requestMappingTemplate: MappingTemplate.dynamoDbPutItem(
        PrimaryKey.partition('id').auto(),
        Values.projecting('todo')),
      responseMappingTemplate: MappingTemplate.dynamoDbResultItem(),
    });

    // Mutation Resolver for updating an exisiting Todo
    todoDS.createResolver({
      typeName: 'Mutation',
      fieldName: 'updateTodo',
      requestMappingTemplate: MappingTemplate.dynamoDbPutItem(
        PrimaryKey.partition('id').is('id'),
        Values.projecting('todo')
      ),
      responseMappingTemplate: MappingTemplate.dynamoDbResultItem(),
    });

    // Mutation Resolver for deleting an exisiting Todo
    todoDS.createResolver({
      typeName: 'Mutation',
      fieldName: 'deleteTodo',
      requestMappingTemplate: MappingTemplate.dynamoDbDeleteItem('id', 'id'),
      responseMappingTemplate: MappingTemplate.dynamoDbResultItem(),
    });

    // defines an AWS Lambda resource
    const testLambda = new lambda.Function(this, 'CDKAppSyncLambdaTest', {
      runtime: lambda.Runtime.NODEJS_12_X,    // execution environment
      code: lambda.Code.asset('lambda-fns'),  // code loaded from the "lambda-fns" directory
      handler: 'callrest.handler',            // file is "callrest", function is "handler"
    });

    /**
     * Add Lambda as a Datasource for the Graphql API.
     */
    const lambdaDs = api.addLambdaDataSource('CDKLambdaTest', 'The test Lambda data source', testLambda);

    // Query Resolver to get all Customers
    lambdaDs.createResolver({
      typeName: 'Query',
      fieldName: 'getLambdaInfo',
      requestMappingTemplate: MappingTemplate.lambdaRequest(),
      responseMappingTemplate: MappingTemplate.lambdaResult(),
    });
    
    // GraphQL API Endpoint
    new cdk.CfnOutput(this, 'Endpoint', {
      value: api.graphQlUrl
    });

    // API Key
    new cdk.CfnOutput(this, 'API_Key', {
      value: apiKey.attrApiKey
    });
  }
}

/*
GraphQL Schema

type Todo {
  id: ID!
  name: String!
  completed: Completed
}

type ModelTodoConnection {
	items: [Todo]
	nextToken: String
}

enum Completed {
  yes
  no
}

type Query {
  listTodos: ModelTodoConnection
  getTodo(id: ID): Todo
  getLambdaInfo: LambdaResponse
}

type LambdaResponse {
  greeting: String
}

type Mutation {
  createTodo(todo: TodoInput!): Todo
  updateTodo(todo: TodoInput!): Todo
  deleteTodo(id: ID!): Todo
}

input TodoInput {
  id: ID!
  name: String
  completed: Completed
}
*/