How to render JSON using Stream Analytics Query - azure

Question

I have Inputs in the form of JSON stored in Blob Storage
I have Output in the form of SQL Azure table.
My wrote query and successfully moving value of specific property in JSON to corresponding Column of SQL Azure table.
Now for one column I want to copy entire JSON payload as Serialized string in one sql column , I am not getting proper library function to do that.
SELECT
CASE
WHEN GetArrayLength(E.event) > 0
THEN GetRecordPropertyValue(GetArrayElement(E.event, 0), 'name')
ELSE ''
END AS EventName
,E.internal.data.id as DataId
,E.internal.data.documentVersion as DocVersion
,E.context.custom As CustomDimensionsPayload
Into OutputTblEvents
FROM InputBlobEvents E
This CustomDimensionsPayload should be a JSON actually

Answer 1

I made a user defined function which did the job for me:
function main(InputJSON) {
var InputJSONString = JSON.stringify(InputJSON);
return InputJSONString;
}
Then, inside the Query, I used the function like this:
SELECT udf.ConvertToJSONString(COLLECT()) AS InputJSON
INTO outputX
FROM inputY

Answer 2

You need to just reference the input object itself instead of COLLECT() if you want the entire payload to be converted. I was trying to do this also so figured I'd add what i did.
I used the same function suggested by PerSchjetne, query then becomes
SELECT udf.JSONToString(IoTInputStream)
INTO [SQLTelemetry]
FROM [IoTInputStream]
Your output will now be the full JSON string, including all the metadata extras that IOT hub adds on.