Function for parsing an Array of data

Streamsheets Community Q&A
1

Hello,
I have an mqtt topic message in json with one key that has as its value an array of data that represents telemetry readings from devices attached to a controller. For this message each devices telemetry reading is a slot in the array.
ex.
{
“controllerID”: 6,
“devicetelemetry”:[23,34,344,22,67]
}

I am looking for a best practice in Stream Sheets to parse this array. It is not clear this is supported without treating the array as a text string and parsing it with split. This seems less than optimal.

thanks in advance for your reply.

2

Hi MrAbsaroka,

Streamsheets does support arrays. In your case it would look like this:

image

{“controllerID”:6,“devicetelemetry”:[23,34,344,22,67]}

To parse the JSON we use the parser from node/javascript.

If the Inbox parses your message as a string there could be two problems:

  1. you don´t send it as a JSON the parser understands
  2. the Consumer is set to “String”.
    image
    image511×773 17.2 KB

If this does not help, can you send me a screenshot of your Inbox (with the message in it), an export of your machine and maybe describe the way you are sending the message to the inbox. :slight_smile:

Cheers

Tizian

3

thank you for your prompt reply and clarification. the problem was indeed how I was structuring my test data generator. Your example clarified how to build the json object so Streamsheets would see it correctly.

4

I should point out the the mqtt message would not work as follows to achieve the result.

for your example I think the message in mqtt would need to be formatted as:
{
“controllerID”:6,
“devicetelemetry”:{“1”:23,“2”:34,“3”:344,“4”:22,“5”:67}
}

So at the point an actual array in the place of the value of the json object does not see to have a solution.

5

Hi MrAbsaroka

The numbers 0,1,2,3,… are only used to describe the array elements in a visual form.
This is the way Streamsheets displays every array.

If data is displayed differently the parser did not interpret it as an array (JSON).
If I understand correctly you still have this problem.
Can you send me an export of what you have done so far and describe how you generate/send your test data. :slight_smile:

Cheers