Not able to send JSON payload request to API end point using HTTPPOST2 ampscript

Question

This is the RMM functionality we have implemented to capture customers response to our Marketing email and send that customer's response to an external API endpoint.

We are trying to send Json payload to an external API endpoint using HTTPPOST2 ampscript function which is implemented in marketing cloud Email. but system is encountering an error with below error , and it is not even reaching to API end point , we are sending customers response to API endpoint using standard RMM Personalization strings

Below is the response we received from HTTPPOST2 ampscript function

{"error":{
"code":"InvalidRequestContent",
"message":"The request content is not valid and could not be deserialized: 
'Unable to translate bytes [B9] at index 355 from specified code page to Unicode.'
."}} " 

Below AMPscript code is implemented in triggered Email , once customer reply to our marketing emails we are triggering emails with below ampscript to send customer's response to endpoint , I can not share Email and email response which causing the issue , but for plain , text email it is working fine we are able to send payload to external API successfully , the issue is with email with some special character or some content not compatible with Json ( not sure)

Below AMPscript code is implemented in triggered Email

%%[

set @FirstName = RequestParameter('FirstName')
set @LastName = RequestParameter('LastName')
set @email = RequestParameter('email')
set @SubscriberKey = _RMM_RecipientSubscriberKey
set @Email_Address = _RMM_RecipientEmailAddress
SET @replymsg = _replycontent


set @authurl = "https://staging/SampleEndpoint/"
set @payload = Concat('{"FirstName": "',@FirstName,'","LastName": "',@LastName,'","Email": "',@email,'","replymsg":"',@replymsg,'","SubscriberKey":"',@SubscriberKey,'","Email_Address":"',@Email_Address,'"}')
set @key = "xxxxxxxxx-secret-key"

SET @httppost = HTTPPost2(@authurl,"application/json",@payload,false,@apistatusCode,@respheader,"Key",@key)


]%%

Not sure if there is any non JSON format character in Payload ?

Answer 1

Two things I noticed in your code:

1. You have two @ symbols in front of the @payload variable
2. You have two commas in a row in your payload CONCAT which is likely causing the issue:

...'","replymsg":"',@replymsg,'",,"SubscriberKey":"',@SubscriberKey,'",,"Email_Address":"',@Email_Address,'"}'

You will see the double comma after @replymsg and after @SubscriberKey.

So it should be:

set @payload = Concat('{"FirstName": "',@FirstName,'","LastName": "',@LastName,'","Email": "',@email,'","replymsg": "',@replymsg,'","SubscriberKey": "',@SubscriberKey,'","Email_Address": "',@Email_Address,'"}')

As to your issue with conflicting characters, likely you will want to do some Replaces on your content to handle potential conflicting characters. For instance something like below examples:

Set @replyMsg = Replace(@replyMsg,'"', '\"')

Which would then escape each of your double quotation marks inside of the replyMsg variable which are most likely the major culprit. Outside that would want to shift things along the lines of { and }, [ and ], etc.