added a missing import when serialising Decimal values

Author: dantownsend

piccolo/apps/migrations/auto/serialisation.py

@@ -2,6 +2,7 @@
 from copy import deepcopy
 from dataclasses import dataclass
 import datetime
+import decimal
 from enum import Enum
 import inspect
 import typing as t
@@ -126,6 +127,7 @@ def serialise_params(params: t.Dict[str, t.Any]) -> SerialisedParams:
             )
             continue
 
+        # Dates and times
         if isinstance(
             value, (datetime.time, datetime.datetime, datetime.date)
         ):
@@ -144,6 +146,12 @@ def serialise_params(params: t.Dict[str, t.Any]) -> SerialisedParams:
             extra_imports.append(Import(module="uuid", target="UUID"))
             continue
 
+        # Decimals
+        if isinstance(value, decimal.Decimal):
+            # Already has a good __repr__.
+            extra_imports.append(Import(module="decimal", target="Decimal"))
+            continue
+
         # Enums
         if isinstance(value, Enum):
             # Enums already have a good __repr__.