fixing some edge cases for UUID column defaults, when using migrations

Author: dantownsend

piccolo/apps/migrations/auto/serialisation.py

@@ -149,7 +149,7 @@ def __eq__(self, other):
         return self.__hash__() == other.__hash__()
 
     def __repr__(self):
-        return f"UUID({str(self.instance)})"
+        return f"UUID('{str(self.instance)}')"
 
 
 ###############################################################################

piccolo/columns/base.py

@@ -7,6 +7,7 @@
 from enum import Enum
 import inspect
 import typing as t
+import uuid
 
 from piccolo.columns.operators.comparison import (
     ComparisonOperator,
@@ -342,6 +343,7 @@ def _validate_default(
         self,
         default: t.Any,
         allowed_types: t.Iterable[t.Union[None, t.Type[t.Any]]],
+        allow_recursion: bool = True,
     ) -> bool:
         """
         Make sure that the default value is of the allowed types.
@@ -357,9 +359,14 @@ def _validate_default(
         ):
             self._validated = True
             return True
-        elif callable(default):
-            self._validated = True
-            return True
+        elif inspect.isfunction(default):
+            # We need to prevent recursion, otherwise a function which returns
+            # a function would be an infinite loop.
+            if allow_recursion and self._validate_default(
+                default(), allowed_types=allowed_types, allow_recursion=False
+            ):
+                self._validated = True
+                return True
         elif (
             isinstance(default, Enum) and type(default.value) in allowed_types
         ):
@@ -536,6 +543,8 @@ def get_sql_value(self, value: t.Any) -> t.Any:
             output = f"'{value.isoformat().replace('T', '')}'"
         elif isinstance(value, bytes):
             output = f"'{value.hex()}'"
+        elif isinstance(value, uuid.UUID):
+            output = f"'{value}'"
         elif isinstance(value, list):
             # Convert to the array syntax.
             output = (

piccolo/columns/column_types.py

@@ -303,11 +303,23 @@ class Band(Table):
     value_type = uuid.UUID
 
     def __init__(self, default: UUIDArg = UUID4(), **kwargs) -> None:
+        if default is UUID4:
+            # In case the class is passed in, instead of an instance.
+            default = UUID4()
+
         self._validate_default(default, UUIDArg.__args__)  # type: ignore
 
         if default == uuid.uuid4:
             default = UUID4()
 
+        if isinstance(default, str):
+            try:
+                default = uuid.UUID(default)
+            except ValueError:
+                raise ValueError(
+                    "The default is a string, but not a valid uuid."
+                )
+
         self.default = default
         kwargs.update({"default": default})
         super().__init__(**kwargs)

piccolo/columns/defaults/uuid.py

@@ -18,7 +18,7 @@ def python(self):
         return uuid.uuid4()
 
 
-UUIDArg = t.Union[UUID4, uuid.UUID, Enum, None]
+UUIDArg = t.Union[UUID4, uuid.UUID, str, Enum, None]
 
 
 __all__ = ["UUIDArg", "UUID4"]

tests/apps/migrations/auto/integration/test_migrations.py

@@ -32,6 +32,10 @@ def integer_default():
     return 1
 
 
+def uuid_default():
+    return uuid.uuid4()
+
+
 @postgres_only
 class TestMigrations(TestCase):
     def tearDown(self):
@@ -139,18 +143,19 @@ def test_uuid_column(self):
                 self.table(column)
                 for column in [
                     UUID(),
-                    # UUID(default="ecf338cd-6da7-464c-b31e-4b2e3e12f0f0"),
-                    # UUID(
-                    #     default=uuid.UUID(
-                    #         "2dfc9c47-adab-4692-b804-f692f3b0fc07"
-                    #     )
-                    # ),
-                    # UUID(default=uuid.uuid4),
-                    # UUID(default=UUID4),
-                    # UUID(null=True),
-                    # UUID(null=False),
-                    # UUID(index=True),
-                    # UUID(index=False),
+                    UUID(default="ecf338cd-6da7-464c-b31e-4b2e3e12f0f0"),
+                    UUID(
+                        default=uuid.UUID(
+                            "2dfc9c47-adab-4692-b804-f692f3b0fc07"
+                        )
+                    ),
+                    UUID(default=uuid.uuid4),
+                    UUID(default=uuid_default),
+                    UUID(default=UUID4()),
+                    UUID(null=True),
+                    UUID(null=False),
+                    UUID(index=True),
+                    UUID(index=False),
                 ]
             ]
         )