Nexus bug fix: accept event type name casing variant used by latest server

[dandavison]

The Nexus link conversion was assuming that the server sends an event type name formatted as CONSTANT_CASE with the EVENT_TYPE_ prefix. However, the latest server sends PascalCase without the prefix:

18:42:52 [ WARNING] Failed to parse event type from Nexus link URL query parameters: Link(url='temporal:///namespaces/default/workflows/367a1427-1d37-470b-a761-30fbd12e7ed7/0197f15b-2963-79d7-814d-352bba12e672/hist
ory?eventID=5&eventType=NexusOperationScheduled&referenceType=EventReference', type='temporal.api.common.v1.Link.WorkflowEvent') (Enum EventType has no value defined for name 'NEXUS_OPERATION_SCHEDULED') (_operatio
n_context.py:550)

temporalio/sdk-go@a10de39

With this PR:

# CLI 1.3.1, Server 1.27.0
#
# send inbound links with StartWorkflow request:
# _query_params_to_event_reference:
# eventID=5&eventType=EVENT_TYPE_NEXUS_OPERATION_SCHEDULED&referenceType=EventReference
# ->
# event_id: 5, event_type: EVENT_TYPE_NEXUS_OPERATION_SCHEDULED

# add outbound links to StartWorkflow response:
# _event_reference_to_query_params:
# event_id: 1, event_type: EVENT_TYPE_WORKFLOW_EXECUTION_STARTED
#  ->
# eventID=1&eventType=WorkflowExecutionStarted&referenceType=EventReference


# CLI 1.4.0 (Server 1.28.0)
#
# send inbound links with StartWorkflow request:
# _query_params_to_event_reference:
# eventID=5&eventType=NexusOperationScheduled&referenceType=EventReference
# ->
# event_id: 5, event_type: EVENT_TYPE_NEXUS_OPERATION_SCHEDULED

# add outbound links to StartWorkflow response:
# _event_reference_to_query_params:
# event_id: 1, event_type: EVENT_TYPE_WORKFLOW_EXECUTION_STARTED
#  ->
# eventID=1&eventType=WorkflowExecutionStarted&referenceType=EventReference

[bergundy]

You also would want to convert to pascal case when you generate a link.

[bergundy]

nit: you could save the list construction in the happy path

Suggested change

	[raw_event_type_name] = query_params.get(LINK_EVENT_TYPE_PARAM_NAME, [None])
	[raw_event_type_name] = query_params.get(LINK_EVENT_TYPE_PARAM_NAME) or [None]

[dandavison]

You also would want to convert to pascal case when you generate a link.

I've done this now.

[dandavison]

Incidentally, there are a couple of bugs in the TS versions of these functions (e.g. \b in a character class is backspace I believe, not word boundary, and the utilities would fail on ContainsAOneLetterWord). Probably doesn't affect their actual usage in practice on event type names. cc @mjameswh

[bergundy]

\b is a word boundary.

[bergundy]

But I do see how this case isn't covered in TS.

[bergundy]

This works though and is more compact:

function pascalCaseToConstantCase(s: string) {
  return s.replace(/\B[A-Z]/g, (m) => `_${m[0]}`).toUpperCase();
}

[dandavison]

\b in a character class is backspace I believe, not word boundary

\b is a word boundary.

Not in a character class, which is how it's being used in sdk-typescript

console.log('a'.match(/\b/))   // ""
console.log('a'.match(/[\b]/)) // null

[bergundy]

This is just a generic helper, nothing to do with event types.

Suggested change

	def _event_type_constant_case_to_pascal_case(s: str) -> str:
	def _constant_case_to_pascal_case(s: str) -> str:

[dandavison]

I decided to qualify their names with the event_type prefix to avoid any implication that they are suitable for use as general case conversion utilities. For example, they have undefined behavior currently if the input doesn't match the expectation that it is already in the expected input form, and the tests don't cover trailing/leading underscores, etc.

[bergundy]

But I do see how this case isn't covered in TS.

[bergundy]

Same here.