Azure-iot-sdk-c: How to get update of only recently updated desired properties?

[hizzawaseem]

My device twin has the following structure where properties A, B and C and so on are being added on run time (not predefined). The JSON object “States” can have up to 160 objects inside.

"desired":
"States": {
"PropertyA": {
"x": 0,
"y": "A"
},
" PropertyB": {
"x": 1,
"y": "B"
},
" PropertyC": {
"x": 2,
"y": "C"
}
}

Currently the complete device twin structure is provided at startup including desired and reported properties, and partial updates are received afterwards. In the device twin partial update I receive the complete object of desired properties.
How can I receive the newly added property only e.g “Property D” or only the most recent changes in a specific property? Is there a predefined function in Azure for this operation?
I do not want to iterate over all the objects inside the “States” object.

[danewalton]

Hi @hizzawaseem
Currently, when updated PATCH requests for twin properties (desired properties) come in to the device, all of the desired properties are sent. So in your example, PropertyA through PropertyD will indeed come in. We do not currently have functionality which only shows the updated "diff".

[danewalton]

I'm going to go ahead and close this for now but please leave a comment if you would like this reopened.

[az-iot-builder-01]

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