Module twin $metadata $lastUpdated property is updated for every desired property

Expected Behavior

The module twin provides metadata for desired properties including a $lastUpdated property which should be updated when the corresponding desired property is updated.

Current Behavior

Updating any property results in the $lastUpdated property being updated for EVERY existing desired property, not just the one that was actually updated.

Steps to Reproduce

1. Create 2 desired properties on a module in the Azure portal and click save.
2. Update the first property to a new value and click save
3. Observe the desired property metadata

Expected: $lastUpdated for the first property should be updated with a new timestamp, while the second property metadata does not change.

Actual: Both values are updated to the same timestamp.

Additional Information

This also happens from the C# SDK RegistryManager from Microsoft.Azure.Devices (v1.17.3)

Example:

var registryClient = RegistryManager.CreateFromConnectionString("connection-string");
var twin = await registryClient.GetTwinAsync(deviceId, moduleId);
twin.Properties.Desired[key] = value;
await registryClient.UpdateTwinAsync(deviceId, moduleId, twin, twin.ETag);

[isyama]

When you update desired properties (or tags), please call UpdateTwin by passing properties that you want to update only; otherwise, we will update all properties passed in the call. For example,

var registryClient = RegistryManager.CreateFromConnectionString(“connection-string”); var twin = await registryClient.GetTwinAsync(deviceId, moduleId);

var twinToUpdate = new Twin(); twinToUpdate.DeviceId = twin.DeviceId; twinToUpdate.ModuleId = twin.ModuleId; twinToUpdate.Properties.Desired[key] = value; await registryClient.UpdateTwinAsync(deviceId, moduleId, twinToUpdate, twin.ETag);

[AMCN41R]

Thanks @isyama. I’d seen those, and just wondered if there were any specific implementation examples (C# for instance). If not, it would be great to see those, but I’m happy to close the ticket.