update.js

import * as dynamoDbLib from "./libs/dynamodb-lib";
import { success, failure } from "./libs/response-lib.js";

export async function main(event, context, callback){
    // Request body is passed in as a JSON embedded string in 'event.body'
    const data = JSON.parse(event.body);
    const params = {
        TableName: "notes",
        // 'Item' contains the attributes of the item to be created // - 'userId': user identities are federated through the
        //             Cognito Identity Pool, we will use the identity id
        //             as the user id of the authenticated user
        // - 'noteId': a unique uuid
        // - 'content': parsed from request body
        // - 'attachment': parsed from request body
        // - 'createdAt': current Unix timestamp
        Key: {
            userId: event.requestContext.identity.cognitoIdentityId,
            noteId: event.pathParameters.id
        },
        UpdateExpression: "SET content = :content, attachment = :attachment",
        ExpressionAttributeValues: {
            ":attachment": data.attachment ? data.attachment : null,
            ":content": data.content ? data.content : null
        },
        ReturnValues: "ALL_NEW"
    };

    try {
        const result = await dynamoDbLib.call("update", params);
        callback(null, success({status: true}));
    } catch(e){
        console.log(e);
        callback(null, failure({status: false}));        
    }
}