Optional chaining operation

[tmccombs]

Terraform Version

1.7.2

Use Cases

Suppose I have an optional variable like:

variable "test" {
  type = object({
     field1 = string
     # and some other fields
    })
  default = null
)

and then somewhere else I need to use use the value of var.test.field, but use a default value of var.test is null.

I would like to be able to do something like:

something = coalesce(var.test?.field1, "default") # the default may actually depend on other variables

Attempted Solutions

I can of course do something like:

something = var.test != null ? var.test.field1 : "default"

but that is awkward and hard to read. It becomes even more so if there are multiple levels of possibly null objects that need to be traversed, especially since && isn't short circuiting.

Another option is to use try:

something = try(var.test.field1, "default")

the problem with this is that if I misspell something in var.test.field1, it will silently use the default instead of giving me an error.

Proposal

Add a .? operator similar to javascript's optional chaining feature.

Or maybe add a function like lookup, except use the default value if the first argument is null.

Or have a variant of try that will still fail for any other error than trying to look up a field on a null value.

References

No response

[crw]

Thanks for this feature request! If you are viewing this issue and would like to indicate your interest, please use the 👍 reaction on the issue description to upvote this issue. We also welcome additional use case descriptions. Thanks again!