Simple example showing a javascript appsync resolver that leverages the use of directy dynamodb integration to perform an "update item" on a dynamodb table.

updateItemResolver.js

export function request (ctx) {
  const { args } = ctx;
  const { blogPost } = args;

  // Any validation logic or transformation/mapping logic

  return {
    operation: 'UpdateItem',
    key: util.dynamodb.toMapValues({ BlogPostId: blogPost.id }),
    update: {
      expression: 'SET #BlogPost = :blogPost',
      expressionNames: { '#BlogPost': 'BlogPost' },
      expressionValues: {
        ':blogPost': util.dynamodb.toDynamoDB(blogPost),
      }
    },
  };
}

export function response (ctx) {
  const { result } = ctx;
  // ... any transformation/mapping logic, etc

  return result.Attributes.BlogPost;
}