refactor: use discriminated unions for Trigger model to eliminate redundant validation

Changes:
- Refactored Trigger.value from dict to typed TriggerValue union
- Added discriminated union support using Literal type for CronTrigger.type
- Removed redundant CronTrigger.model_validate() call in verify_graph.py
- Updated all tests to include type field in trigger value dicts

Benefits:
- Single validation at request time (no re-validation needed)
- Type safety with IDE autocomplete and static analysis
- Cleaner code: trigger.value.expression vs trigger.value["expression"]
- Extensible: easy to add new trigger types to the union
- All 38 trigger-related tests passing

Also bumped python-sdk version to 0.0.3b2

Author: spa-raj

python-sdk/exospherehost/_version.py

@@ -1 +1 @@
-version = "0.0.3b1"
+version = "0.0.3b2"

state-manager/app/models/trigger_models.py

@@ -1,7 +1,7 @@
-from pydantic import BaseModel, Field, field_validator, model_validator
+from pydantic import BaseModel, Field, field_validator
 from enum import Enum
 from croniter import croniter
-from typing import Self, Optional
+from typing import Union, Annotated, Optional, Literal
 from zoneinfo import available_timezones
 
 # Cache available timezones at module level to avoid repeated filesystem queries
@@ -18,6 +18,7 @@ class TriggerStatusEnum(str, Enum):
     TRIGGERING = "TRIGGERING"
 
 class CronTrigger(BaseModel):
+    type: Literal[TriggerTypeEnum.CRON] = Field(default=TriggerTypeEnum.CRON, description="Type of the trigger")
     expression: str = Field(..., description="Cron expression for the trigger")
     timezone: Optional[str] = Field(default="UTC", description="Timezone for the cron expression (e.g., 'America/New_York', 'Europe/London', 'UTC')")
 
@@ -37,14 +38,16 @@ def validate_timezone(cls, v: Optional[str]) -> str:
             raise ValueError(f"Invalid timezone: {v}. Must be a valid IANA timezone (e.g., 'America/New_York', 'Europe/London', 'UTC')")
         return v
 
+# Union type for all trigger types - add new trigger types here
+TriggerValue = Annotated[Union[CronTrigger], Field(discriminator="type")]
+
 class Trigger(BaseModel):
+    """
+    Extensible trigger model using discriminated unions.
+    To add a new trigger type:
+    1. Add the enum value to TriggerTypeEnum
+    2. Create a new trigger class (e.g., WebhookTrigger) with type field
+    3. Add it to the TriggerValue Union
+    """
     type: TriggerTypeEnum = Field(..., description="Type of the trigger")
-    value: dict = Field(default_factory=dict, description="Value of the trigger")
-
-    @model_validator(mode="after")
-    def validate_trigger(self) -> Self:
-        if self.type == TriggerTypeEnum.CRON:
-            CronTrigger.model_validate(self.value)
-        else:
-            raise ValueError(f"Unsupported trigger type: {self.type}")
-        return self
+    value: TriggerValue = Field(..., description="Value of the trigger")

state-manager/app/tasks/verify_graph.py

@@ -11,6 +11,7 @@
 from app.singletons.logs_manager import LogsManager
 from app.models.trigger_models import TriggerStatusEnum, TriggerTypeEnum
 from app.models.db.trigger import DatabaseTriggers
+from app.models.trigger_models import CronTrigger
 
 # Cache UTC timezone at module level to avoid repeated instantiation
 UTC = ZoneInfo("UTC")
@@ -105,13 +106,12 @@ async def verify_inputs(graph_template: GraphTemplate, registered_nodes: list[Re
     return errors
 
 async def create_crons(graph_template: GraphTemplate):
-    # Build a map of (expression, timezone) -> validated CronTrigger for deduplication
+    # Build a map of (expression, timezone) -> CronTrigger for deduplication
     triggers_to_create = {}
     for trigger in graph_template.triggers:
         if trigger.type == TriggerTypeEnum.CRON:
-            # Validate through CronTrigger model to normalize timezone (None -> "UTC")
-            from app.models.trigger_models import CronTrigger
-            cron_trigger = CronTrigger.model_validate(trigger.value)
+            # trigger.value is already a validated CronTrigger instance
+            cron_trigger = trigger.value
             triggers_to_create[(cron_trigger.expression, cron_trigger.timezone)] = cron_trigger
 
     current_time = datetime.now(UTC).replace(tzinfo=None)

state-manager/tests/unit/models/test_trigger_models.py

@@ -84,27 +84,28 @@ def test_valid_trigger_with_cron_and_timezone(self):
         """Test creating a valid trigger with CRON type and timezone"""
         trigger = Trigger(
             type=TriggerTypeEnum.CRON,
-            value={"expression": "0 9 * * *", "timezone": "America/New_York"}
+            value={"type": TriggerTypeEnum.CRON, "expression": "0 9 * * *", "timezone": "America/New_York"}
         )
         assert trigger.type == TriggerTypeEnum.CRON
-        assert trigger.value["expression"] == "0 9 * * *"
-        assert trigger.value["timezone"] == "America/New_York"
+        assert trigger.value.expression == "0 9 * * *"
+        assert trigger.value.timezone == "America/New_York"
 
     def test_valid_trigger_with_cron_without_timezone(self):
         """Test creating a valid trigger with CRON type without timezone"""
         trigger = Trigger(
             type=TriggerTypeEnum.CRON,
-            value={"expression": "0 9 * * *"}
+            value={"type": TriggerTypeEnum.CRON, "expression": "0 9 * * *"}
         )
         assert trigger.type == TriggerTypeEnum.CRON
-        assert trigger.value["expression"] == "0 9 * * *"
+        assert trigger.value.expression == "0 9 * * *"
+        assert trigger.value.timezone == "UTC"  # Should default to UTC
 
     def test_invalid_trigger_with_invalid_cron_expression(self):
         """Test creating a trigger with invalid cron expression"""
         with pytest.raises(ValidationError) as exc_info:
             Trigger(
                 type=TriggerTypeEnum.CRON,
-                value={"expression": "invalid cron"}
+                value={"type": TriggerTypeEnum.CRON, "expression": "invalid cron"}
             )
 
         errors = exc_info.value.errors()
@@ -115,7 +116,7 @@ def test_invalid_trigger_with_invalid_timezone(self):
         with pytest.raises(ValidationError) as exc_info:
             Trigger(
                 type=TriggerTypeEnum.CRON,
-                value={"expression": "0 9 * * *", "timezone": "Invalid/Zone"}
+                value={"type": TriggerTypeEnum.CRON, "expression": "0 9 * * *", "timezone": "Invalid/Zone"}
             )
 
         errors = exc_info.value.errors()

state-manager/tests/unit/tasks/test_create_crons.py

@@ -14,6 +14,14 @@
 from app.tasks.verify_graph import create_crons
 from app.models.trigger_models import Trigger, TriggerTypeEnum
 
+# Helper function to create trigger value dict
+def make_trigger_value(expression: str, timezone: str = None):
+    """Helper to create trigger value dict with required 'type' field"""
+    result = {"type": TriggerTypeEnum.CRON, "expression": expression}
+    if timezone is not None:
+        result["timezone"] = timezone
+    return result
+
 
 @pytest.mark.asyncio
 async def test_create_crons_with_america_new_york_timezone():
@@ -24,7 +32,7 @@ async def test_create_crons_with_america_new_york_timezone():
     graph_template.triggers = [
         Trigger(
             type=TriggerTypeEnum.CRON,
-            value={"expression": "0 9 * * *", "timezone": "America/New_York"}
+            value=make_trigger_value("0 9 * * *", "America/New_York")
         )
     ]
 
@@ -58,7 +66,7 @@ async def test_create_crons_with_default_utc_timezone():
     graph_template.triggers = [
         Trigger(
             type=TriggerTypeEnum.CRON,
-            value={"expression": "0 9 * * *"}  # No timezone specified
+            value=make_trigger_value("0 9 * * *")  # No timezone specified
         )
     ]
 
@@ -83,7 +91,7 @@ async def test_create_crons_with_europe_london_timezone():
     graph_template.triggers = [
         Trigger(
             type=TriggerTypeEnum.CRON,
-            value={"expression": "0 17 * * *", "timezone": "Europe/London"}
+            value=make_trigger_value("0 17 * * *", "Europe/London")
         )
     ]
 
@@ -108,11 +116,11 @@ async def test_create_crons_with_multiple_different_timezones():
     graph_template.triggers = [
         Trigger(
             type=TriggerTypeEnum.CRON,
-            value={"expression": "0 9 * * *", "timezone": "America/New_York"}
+            value=make_trigger_value("0 9 * * *", "America/New_York")
         ),
         Trigger(
             type=TriggerTypeEnum.CRON,
-            value={"expression": "0 17 * * *", "timezone": "Europe/London"}
+            value=make_trigger_value("0 17 * * *", "Europe/London")
         )
     ]
 
@@ -159,11 +167,11 @@ async def test_create_crons_deduplicates_same_expression_and_timezone():
     graph_template.triggers = [
         Trigger(
             type=TriggerTypeEnum.CRON,
-            value={"expression": "0 9 * * *", "timezone": "America/New_York"}
+            value=make_trigger_value("0 9 * * *", "America/New_York")
         ),
         Trigger(
             type=TriggerTypeEnum.CRON,
-            value={"expression": "0 9 * * *", "timezone": "America/New_York"}
+            value=make_trigger_value("0 9 * * *", "America/New_York")
         )
     ]
 
@@ -190,11 +198,11 @@ async def test_create_crons_keeps_same_expression_different_timezones():
     graph_template.triggers = [
         Trigger(
             type=TriggerTypeEnum.CRON,
-            value={"expression": "0 9 * * *", "timezone": "America/New_York"}
+            value=make_trigger_value("0 9 * * *", "America/New_York")
         ),
         Trigger(
             type=TriggerTypeEnum.CRON,
-            value={"expression": "0 9 * * *", "timezone": "Europe/London"}
+            value=make_trigger_value("0 9 * * *", "Europe/London")
         )
     ]
 
@@ -221,7 +229,7 @@ async def test_create_crons_trigger_time_is_datetime():
     graph_template.triggers = [
         Trigger(
             type=TriggerTypeEnum.CRON,
-            value={"expression": "0 9 * * *", "timezone": "America/New_York"}
+            value=make_trigger_value("0 9 * * *", "America/New_York")
         )
     ]
 
@@ -244,7 +252,7 @@ async def test_create_crons_with_null_timezone_normalizes_to_utc():
     graph_template.triggers = [
         Trigger(
             type=TriggerTypeEnum.CRON,
-            value={"expression": "0 9 * * *", "timezone": None}  # Explicit None
+            value={"type": TriggerTypeEnum.CRON, "expression": "0 9 * * *", "timezone": None}  # Explicit None
         )
     ]