Start async handlers as copy of sync handlers

Author: dandavison

Diff for: message_passing/introduction/workflow_with_async_handlers.py

@@ -0,0 +1,70 @@
+from dataclasses import dataclass
+from enum import IntEnum
+from typing import Optional
+
+from temporalio import workflow
+
+
+class Language(IntEnum):
+    CHINESE = 1
+    ENGLISH = 2
+    FRENCH = 3
+    SPANISH = 4
+    PORTUGUESE = 5
+
+
+@dataclass
+class GetLanguagesInput:
+    include_unsupported: bool
+
+
+@dataclass
+class ApproveInput:
+    name: str
+
+
+@workflow.defn
+class GreetingWorkflow:
+    def __init__(self) -> None:
+        self.approved_for_release = False
+        self.approver_name: Optional[str] = None
+        self.language = Language.ENGLISH
+        self.greetings = {
+            Language.ENGLISH: "Hello, world",
+            Language.CHINESE: "你好，世界",
+        }
+
+    @workflow.run
+    async def run(self) -> str:
+        await workflow.wait_condition(lambda: self.approved_for_release)
+        return self.greetings[self.language]
+
+    @workflow.query
+    def get_languages(self, input: GetLanguagesInput) -> list[Language]:
+        # 👉 A Query handler returns a value: it can inspect but must not mutate the Workflow state.
+        if input.include_unsupported:
+            return list(Language)
+        else:
+            return list(self.greetings)
+
+    @workflow.signal
+    def approve(self, input: ApproveInput) -> None:
+        # 👉 A Signal handler mutates the Workflow state but cannot return a value.
+        self.approved_for_release = True
+        self.approver_name = input.name
+
+    @workflow.update
+    def set_language(self, language: Language) -> Language:
+        # 👉 An Update handler can mutate the Workflow state and return a value.
+        previous_language, self.language = self.language, language
+        return previous_language
+
+    @set_language.validator
+    def validate_language(self, language: Language) -> None:
+        if language not in self.greetings:
+            # 👉 In an Update validator you raise any exception to reject the Update.
+            raise ValueError(f"{language.name} is not supported")
+
+    @workflow.query
+    def get_language(self) -> Language:
+        return self.language