Google Apps Script: Amazon SP-API Add parameters to the request - amazon-web-services

Question

I'm trying to add additional parameters to my call to Amazon Selling Partner API.
The calls I'm doing at the moment is point at Amazon Get Orders
I'd like to add two parameters: MarketplaceIds(required, array) and OrderStatuses(optional, string; e.g.: "Shipped").
My question is:
shall this go only as part of the request or it also impacts on the canonical request?
and how to implement it?
This is my code so far:
function GetOrders(){
var access_token = AccessToken();
//Time variables
var currentDate = new Date();
var isoDate = currentDate.toISOString();
var isoString = isoDate.replace(/-/g, "").replace(/:/g, "").replace(/(\.\d{3})/, "");
var yearMonthDay= Utilities.formatDate(currentDate, 'GTM-5', 'yyyyMMdd');
//API variables
var end_point = 'https://sellingpartnerapi-eu.amazon.com';
//Credential variables
var aws_region = "eu-west-1";
var service = "execute-api";
var termination_string = "aws4_request";
//CanonicalRequest = httpRequestMethod + '\n' + CanonicalURI + '\n' + CanonicalQueryString + '\n' + CanonicalHeaders + '\n' + SignedHeaders + '\n' + HexEncode(Hash(RequestPayload));
//CanonicalRequest components:
var httpRequestMethod = 'GET';
var canonicalURI = '/orders/v0/orders';
var canonicalQueryString = '?marketplaceId=A1PA6795UKMFR9';
var canonicalheaders = 'host:' + "sellingpartnerapi-eu.amazon.com" + '\n' + 'user-agent:' + 'Mozilla/5.0 (compatible; Google-Apps-Script; beanserver; +https://script.google.com; id: UAEmdDd-KyWEWcR137UzUzWb1fu3rUgNviHA)' + '\n' + 'x-amz-access-token:' + access_token + '\n' + 'x-amz-date:' + isoDate;
var signedheaders = 'host;user-agent;x-amz-access-token;x-amz-date';//;user-agent & host; al comienzo
var requestPayloadHashed = Utilities.computeDigest(Utilities.DigestAlgorithm.SHA_256, "");
requestPayloadHashed = requestPayloadHashed.map(function(e) {return ("0" + (e < 0 ? e + 256 : e).toString(16)).slice(-2)}).join("");
//Building the canonical request
var canonical_string = httpRequestMethod + '\n' + canonicalURI + '\n' + "marketplaceId=A1PA6795UKMFR9" + '\n' + canonicalheaders + '\n\n' + signedheaders + '\n' + requestPayloadHashed;//UPDATED
var canonical_signature = Utilities.computeDigest(Utilities.DigestAlgorithm.SHA_256, canonical_string);
canonical_request = canonical_signature.map(function(e) {return ("0" + (e < 0 ? e + 256 : e).toString(16)).slice(-2)}).join("");
//CredentialScope = Date + AWS region + Service + Termination string;
//StringToSign = Algorithm + \n + RequestDateTime + \n + CredentialScope + \n + HashedCanonicalRequest;
var credential_scope = yearMonthDay + '/' + aws_region + '/' + service + '/' + termination_string;
var string_to_sign = "AWS4-HMAC-SHA256" + '\n' + isoString + '\n' + credential_scope + '\n' + canonical_request;
var kSecret = ACCESS_KEY;
var kDate = Utilities.computeHmacSha256Signature(yearMonthDay, "AWS4" + kSecret);
var kRegion = Utilities.computeHmacSha256Signature(toBytes(aws_region), kDate);
var kService = Utilities.computeHmacSha256Signature(toBytes(service), kRegion);
var kSigning = Utilities.computeHmacSha256Signature(toBytes(termination_string), kService);
var signature = hex(Utilities.computeHmacSha256Signature(toBytes(string_to_sign), kSigning));
var options = {
'method': 'GET',
'headers': {
//'host': end_point,
'user-agent': 'Mozilla/5.0 (compatible; Google-Apps-Script; beanserver; +https://script.google.com; id: UAEmdDd-KyWEWcR137UzUzWb1fu3rUgNviHA)',
'x-amz-access-token': access_token,
'x-amz-date': isoDate,
'Authorization': 'AWS4-HMAC-SHA256 Credential=' + ACCESS_ID + '/' + credential_scope + ', SignedHeaders=' + signedheaders + ', Signature=' + signature,
},
'muteHttpExceptions': true
}
var getOrders = UrlFetchApp.fetch(end_point + canonicalURI + canonicalQueryString, options);
Logger.log(getOrders);
}
I already have a variable marketplaceId on my canonicalQueryString parameter but using it as it is I'm getting the following response:
{
"errors": [
{
"message": "Missing or invalid request parameters: [MarketplaceIds]",
"code": "InvalidInput"
}
]
}

Answer 1

Change
var canonicalQueryString = '?marketplaceId=A1PA6795UKMFR9';
to
var canonicalQueryString = '?MarketplaceIds=A1PA6795UKMFR9';