How to pass attributes in Ampscript rest api block for outbound SMS?

Question

I am trying to trigger outbound SMS for another outbound SMS, I am able to trigger it but not able to pass the subscriber key and attributes in the payload. Below is the script that's working with only mobile number in the content.

%%[
    VAR @apiid,@url,@exec,@accessToken,@mobileNumber,@OMedia,@apiresponse,@apistatusCode,@statusCode,@response,@httppost,@apitoken,@skey,@cpk1
    set @mobileNumber = "xxxxxx"
    set @skey="123#Test"
    set @cpk1="123##Test"
    SET @apiid = '{"client_id": "xxxxxx","client_secret": "xxxxx", "grant_type": "client_credentials"}'
    SET @httppost = HTTPPost2("https://subdomain.auth.marketingcloudapis.com/v2/token","application/json",@apiid,false,@apistatusCode,@apiresponse)
    SET @apitoken = Substring(@apistatusCode,18,512)
    IF @httppost ==  200 THEN
    SET @OMedia = concat('{"mobileNumbers":[', @mobileNumber,']}')
     
      SET @url ="https://subdomain.rest.marketingcloudapis.com/sms/v1/messageContact/**smskey**/send/"
    SET @exec = HTTPPost2(@url,"application/json",@OMedia,true,@statusCode,@response,'Authorization',CONCAT("Bearer ", @apitoken)) 
    ENDIF
]%%

but when I try to pass attributes in the payload content like below its not working

SET @OMedia = concat('{"Subscribers": [{"mobileNumbers":[', @mobileNumber,'],"SubscriberKey": [',@skey,'],"Attributes":{"COMPOSITE_PRIMARY_KEY":[', @cpk1,']}}]}')

Is there a way to pass a unique key to next message from current message through API?

Answer 1

I think you are using this SMS API - https://developer.salesforce.com/docs/atlas.en-us.mc-apis.meta/mc-apis/postMessageContactSend.htm

If so, looking at the second example. You payload seems to be incorrect. Please try with API tools like Postman and try to write the ampscript.

In your payload it should be 'MobileNumber' instead of mobileNumbers. Remove the array brackets. So, it should be looking like below:

SET @OMedia = concat('{"Subscribers": [{"MobileNumber":"', @mobileNumber,'","SubscriberKey":"',@skey,'","Attributes":{"COMPOSITE_PRIMARY_KEY":"', @cpk1,'"}}]}')

Let me know if this helps!