User-defined types optional property failing bicep deployment

[georgeollis]

Hi, just curious, is this a known restriction within bicep or am I missing something? I'm trying to deploy an AVD host pool, I'm using a hostPoolProperties type with an optional friendlyName string. See below

I'm validating that the string may be null, and if so, it won't be used within the deployment.

I'm then calling the bicep file via a module that isn't specifying the friendlyName attribute because it's optional. Is the error expected?

[jeskew]

The expression empty(hostPoolObject.friendlyName) is what is failing at runtime because attempting to access a missing property in ARM will raise an error. There's an explanation for why ARM behaves this way in #11912 (comment)

Bicep introduced the .? (safe dereference) to try to help with this. empty(hostPoolObject.?friendlyName) will return false if the friendlyName property is missing, null, or an empty string (hostPoolObject.?friendlyName will evaluate to null if the property is missing).

It might help to have a linter rule that emits a warning diagnostic with a quick fix to replace a . (property access) operator with a .? operator if the accessed property is nullable.

[georgeollis]

Awesome, thank you. I would love to see that linter rule added.

[anthony-c-martin]

Closed by #15838