Newline encoding in url to SNS Service

Question

Hi,  
  
I am triggering the SNS Service through the API Gateway.  
My RequestBody looks like this:  
{  
    "sender_id": "Alias",  
    "phone_number": "+4912345678",  
    "message_text": "Break 
 here"  
}  
  
The Url Query Parameter is mapped like this:  
Message	method.request.body.message_text  
Action Publish  
  
etc.  
This alone should work fine, but it isn't, as it's passed to the SNS service via URL and the 
 gets decoded to %5Cn.   
"Action=Publish&Message=Break_%5Cn_here"  
This should be passed as %0A. Even writing "Break %0A here" in the message is not working as the % is then urlencoded as %25, which results in %250A in the URL and a '%0A' in the received SMS.  
  
I tried overwriting the Message through a Mapping Template and using $util.javaScriptEscape and so on.. Nothing works, it's always too heavy encoded. Is there a way to trick AWS into not doing this? Or a way to pass the Message other than through the URL Query?  
  
I hope this request is detailed enough, thanks in advance.

Answer

Thanks to the AWS Support the problem has been solved. It was wrong to use URL Query Parameters. I removed all of them.  
I needed one HTTP Header: Content-Type: 'application/x-www-form-urlencoded'  
  
Then I used a Messaging Template like this:  
#set($message = $input.path('$.message_text'))  
#set($phoneNumber = $input.path('$.phone_number'))  
Action=Publish&PhoneNumber=$util.urlEncode($phoneNumber)&Message=$util.urlEncode($message)&MessageAttributes.entry.1.Name=AWS.SNS.SMS.SenderID&MessageAttributes.entry.1.Value.DataType=String&MessageAttributes.entry.1.Value.StringValue=Alias  
  
Having my JSON Object in the Request like this:  
{  
    "phone_number": "+4912345678",  
    "message_text": "Break
Here",  
    "sender_id":"Alias"  
}  
  
Works perfectly fine with a line break

Newline encoding in url to SNS Service

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