Refactor: ensurer revision documents with created_at field is added/m…

…odified on point of creation

agenta-backend/agenta_backend/models/db_models.py

@@ -104,7 +104,7 @@ class AppVariantRevisionsDB(Document):
     modified_by: Link[UserDB]
     base: Link[VariantBaseDB]
     config: ConfigDB
-    created_at: Optional[datetime] = Field(default=datetime.now())
+    created_at: datetime
     updated_at: Optional[datetime] = Field(default=datetime.now())
 
     class Settings:
@@ -131,7 +131,7 @@ class AppEnvironmentRevisionDB(Document):
     modified_by: Link[UserDB]
     deployed_app_variant_revision: Optional[PydanticObjectId]
     deployment: Optional[PydanticObjectId]  # reference to deployment
-    created_at: Optional[datetime] = Field(default=datetime.utcnow())
+    created_at: datetime
 
     class Settings:
         name = "environments_revisions"

agenta-backend/agenta_backend/services/db_manager.py

@@ -404,6 +404,7 @@ async def create_new_app_variant(
         modified_by=user,
         base=base,
         config=config,
+        created_at=datetime.now()
     )
     await variant_revision.create()
 
@@ -891,6 +892,7 @@ async def add_variant_from_base_and_config(
         modified_by=user_db,
         base=base_db,
         config=config_db,
+        created_at=datetime.now()
     )
     await variant_revision.create()
 
@@ -1284,6 +1286,7 @@ async def create_environment_revision(
         environment=environment,
         revision=environment.revision,
         modified_by=user,
+        created_at=datetime.now()
     )
 
     if kwargs:
@@ -1497,6 +1500,7 @@ async def update_variant_parameters(
             modified_by=user,
             base=app_variant_db.base,
             config=config_db,
+            created_at=datetime.now()
         )
         await variant_revision.save()