"errorType": "TypeError",
"errorMessage": "Cannot read property 'origin' of undefined",
"trace": [
"TypeError: Cannot read property 'origin' of undefined",
"    at responseHeaders (/var/task/index.js:32:26)",
"    at /var/task/index.js:124:22",
"    at processTicksAndRejections (internal/process/task_queues.js:95:5)"
]

/**********************************************************************
*  Upsert Answer item into table
**********************************************************************/
/* POST test
{
"resource": "/",
"path": "/",
"httpMethod": "POST",
"body": "{\"answer\":\"This is my super important answer\",\"questionSlug\":\"this-is-my-super-important-answer\"}"
}
PUT test - make sure to change the ID to one in your database before running or this method will create a new record
{
"resource": "/",
"path": "/",
"httpMethod": "PUT",
"body": "{\"answer\":\"This is my super important answer\",\"negativeVotes\":0,\"positiveVotes\":1,\"id\":\"5ec9957e3f64b70004e7599e\"}"
}
*/
// we need access to the AWS SDK
var AWS = require("aws-sdk");
// we need uuid to generate unique ids
const { v4: uuidv4 } = require("uuid");
//  we need access to DynamoDB and choose the DocumentClient model
var docClient = new AWS.DynamoDB.DocumentClient();
const responseHeaders = (headers) => {
const origin = headers.origin || headers.Origin;
return {
// HTTP headers to pass back to the client
"Content-Type": "application/json",
// the next headers support CORS
"X-Requested-With": "*",
"Access-Control-Allow-Headers":
"Content-Type,X-Amz-Date,Authorization,X-Api-Key,x-requested-with",
"Access-Control-Allow-Origin": origin,
"Access-Control-Allow-Methods": "OPTIONS,*",
Vary: "Origin", // for proxies
// the "has-cors" library used by the Angular application wants this set
"Access-Control-Allow-Credentials": "true",
};
};
exports.handler = async (event) => {
// get the HTTP Method used
var httpMethod = event.httpMethod;
// get the HTTP body sent
var payload = JSON.parse(event.body);
// time to prepare the upsert
const paramQuery = async () => {
// define our query
let params = {
TableName: "Answer",
Key: { id: "" },
UpdateExpression: "set #qi = :qi, #a = :a, #nv = :nv, #pv = :pv",
ExpressionAttributeNames: {
// define the attributes used in the update expression
"#qi": "questionId",
"#a": "answer",
"#nv": "negativeVotes",
"#pv": "positiveVotes",
},
ExpressionAttributeValues: {
// set default values
":qi": "",
":a": "",
":nv": 0,
":pv": 0,
},
// this tells DynamoDB to return the new records with all fields, not just the changed ones
// see https://docs.aws.amazon.com/amazondynamodb/latest/APIReference/API_UpdateItem.html for
// information on the possible values
ReturnValues: "ALL_NEW",
};
// these three fields can be set during create or update
//  set the answer if there is one
if (payload.answer && payload.answer.trim())
params.ExpressionAttributeValues[":a"] = payload.answer;
//  set the category slug if there is one
if (payload.questionId && payload.questionId.trim())
params.ExpressionAttributeValues[":qi"] = payload.questionId;
if (httpMethod == "PUT") {
// PUTs are updates but the ID is passed as a path paremeter
// lets get the path parameters
let pathParameters = event.pathParameters;
//  set the unique key of the item to be modified
params.Key.id = pathParameters.id;
// these two values are only changed - they are always defaulted during create
//  set the negativeVotes
params.ExpressionAttributeValues[":nv"] = payload.negativeVotes;
//  set the positiveVotes
params.ExpressionAttributeValues[":pv"] = payload.positiveVotes;
} else {
// POSTs are inserts
// create and set the unique key. its a uuid without the '-'
var id = uuidv4().replace(/\-/g, "");
params.Key.id = id;
}
// uncomment the next line to see the parameters as sent to DynamoDB
//console.log(JSON.stringify(params));
// we create a promise to wrap the async DynamoDB execution
return new Promise((resolve, reject) => {
var queryParams = docClient.update(params).promise();
queryParams
.then(function (data) {
resolve({
statusCode: 200,
body: JSON.stringify(data),
// HTTP headers to pass back to the client
headers: responseHeaders(event.headers),
});
})
.catch(function (err) {
reject(err);
});
});
};
// we await our promise here and return the result (see the resolve above)
return await paramQuery();
};

const origin = headers.origin || headers.Origin;

 "Access-Control-Allow-Origin": origin,