Cannot invoke C2D command with JSON argument when using typescript

[rerkcp]

Context

• OS and version used: <Ubuntu 20.04>
• Node.js version: <v14.17.2>
• npm version: <7.20.2>
• list of installed packages: <
  [email protected] /e2e-test
  ├── @azure/[email protected]
  ├── @types/[email protected]
  ├── @types/[email protected]
  ├── [email protected]
  ├── [email protected]
  ├── [email protected]
  ├── [email protected]
  ├── [email protected]
  └── [email protected] >

Description of the issue

Problem 1: cannot hand JS object to invokeCommand directly

const digitalTwinClient = new iothub.DigitalTwinClient(new iothub.IoTHubTokenCredentials(connectionString));
const argument = { Name: 'test', Config: 'someconfig' };
return await digitalTwinClient.invokeCommand(deviceId, 'command', argument);

This fails to compile in typescript, because the typescript bindings only allow the argument to be a string.

Problem 2: SDK adds a layer of escaping when argument is already translated to string containing JSON.

const digitalTwinClient = new iothub.DigitalTwinClient(new iothub.IoTHubTokenCredentials(connectionString));
const argument = { Name: 'test', Config: 'someconfig' };
return await digitalTwinClient.invokeCommand(deviceId, 'command', JSON.stringify(argument));

This compiles, but the device receives not the expected argument

{ "Name": "test", "Config": "someconfig:" }

but

"{ \"Name\": \"test\", \"Config\": \"someconfig:\" }"

which obviously is not the format the device expects the argument to be.

Workaround (by falling back to JS behavior):

const digitalTwinClient = new iothub.DigitalTwinClient(new iothub.IoTHubTokenCredentials(connectionString));
const argument = { Name: 'test', Config: 'someconfig' };
const dummyClient : any = digitalTwinClient;
return await client.invokeCommand(deviceId, 'command', argument);

This works, but is unintuitive and eliminates type safety for the invokeCommand and the response.

If a better workaround is available please state, but maybe this should also be something added to the typescript examples.

[anthonyvercolano]

Fixed in release 09/09/21