make sure deallocation fixes view model too [deallocation_to_readmodel]

Author: hjwp

src/allocation/domain/events.py

@@ -14,6 +14,13 @@ class Allocated(Event):
     batchref: str
 
 
+@dataclass
+class Deallocated(Event):
+    orderid: str
+    sku: str
+    qty: int
+
+
 @dataclass
 class OutOfStock(Event):
     sku: str

src/allocation/domain/model.py

@@ -35,7 +35,7 @@ def change_batch_quantity(self, ref: str, qty: int):
         batch._purchased_quantity = qty
         while batch.available_quantity < 0:
             line = batch.deallocate_one()
-            self.events.append(commands.Allocate(line.orderid, line.sku, line.qty))
+            self.events.append(events.Deallocated(line.orderid, line.sku, line.qty))
 
 
 @dataclass(unsafe_hash=True)

src/allocation/service_layer/handlers.py

@@ -1,5 +1,6 @@
 # pylint: disable=unused-argument
 from __future__ import annotations
+from dataclasses import asdict
 from typing import TYPE_CHECKING
 from allocation.adapters import email, redis_eventpublisher
 from allocation.domain import commands, events, model
@@ -39,6 +40,16 @@ def allocate(
         uow.commit()
 
 
+def reallocate(
+    event: events.Deallocated,
+    uow: unit_of_work.AbstractUnitOfWork,
+):
+    with uow:
+        product = uow.products.get(sku=event.sku)
+        product.events.append(commands.Allocate(**asdict(event)))
+        uow.commit()
+
+
 def change_batch_quantity(
     cmd: commands.ChangeBatchQuantity,
     uow: unit_of_work.AbstractUnitOfWork,
@@ -82,3 +93,18 @@ def add_allocation_to_read_model(
             dict(orderid=event.orderid, sku=event.sku, batchref=event.batchref),
         )
         uow.commit()
+
+
+def remove_allocation_from_read_model(
+    event: events.Deallocated,
+    uow: unit_of_work.SqlAlchemyUnitOfWork,
+):
+    with uow:
+        uow.session.execute(
+            """
+            DELETE FROM allocations_view
+            WHERE orderid = :orderid AND sku = :sku
+            """,
+            dict(orderid=event.orderid, sku=event.sku),
+        )
+        uow.commit()

src/allocation/service_layer/messagebus.py

@@ -60,6 +60,10 @@ def handle_command(
         handlers.publish_allocated_event,
         handlers.add_allocation_to_read_model,
     ],
+    events.Deallocated: [
+        handlers.remove_allocation_from_read_model,
+        handlers.reallocate,
+    ],
     events.OutOfStock: [handlers.send_out_of_stock_notification],
 }  # type: Dict[Type[events.Event], List[Callable]]
 

tests/integration/test_views.py

@@ -21,3 +21,15 @@ def test_allocations_view(sqlite_session_factory):
         {"sku": "sku1", "batchref": "sku1batch"},
         {"sku": "sku2", "batchref": "sku2batch"},
     ]
+
+
+def test_deallocation(sqlite_session_factory):
+    uow = unit_of_work.SqlAlchemyUnitOfWork(sqlite_session_factory)
+    messagebus.handle(commands.CreateBatch("b1", "sku1", 50, None), uow)
+    messagebus.handle(commands.CreateBatch("b2", "sku1", 50, today), uow)
+    messagebus.handle(commands.Allocate("o1", "sku1", 40), uow)
+    messagebus.handle(commands.ChangeBatchQuantity("b1", 10), uow)
+
+    assert views.allocations("o1", uow) == [
+        {"sku": "sku1", "batchref": "b2"},
+    ]