feat: enhance foreign key handling and add validation

- Updated `foreign_key` method in `BaseModel` to accept additional keyword arguments for flexibility.
- Added null check handling in `TypeIDType` methods for improved robustness.
- Integrated relationships and foreign key handling in test cases, ensuring enhanced functionality and validation of models.

Generated-by: aiautocommit

activemodel/base_model.py

@@ -145,16 +145,18 @@ def __tablename__(cls) -> str:
         return pydash.strings.snake_case(cls.__name__)
 
     @classmethod
-    def foreign_key(cls):
+    def foreign_key(cls, **kwargs):
         """
         Returns a Field object referencing the foreign key of the model.
         """
 
+        field_options = {"nullable": False} | kwargs
+
         return Field(
             # TODO id field is hard coded, should pick the PK field in case it's different
             sa_type=cls.model_fields["id"].sa_column.type,  # type: ignore
             foreign_key=f"{cls.__tablename__}.id",
-            nullable=False,
+            **field_options,
         )
 
     @classmethod

activemodel/types/typeid.py

@@ -55,6 +55,9 @@ def process_bind_param(self, value, dialect):
         This is run when a search query is built or ...
         """
 
+        if value is None:
+            return None
+
         if isinstance(value, UUID):
             # then it's a UUID class, such as UUID('01942886-7afc-7129-8f57-db09137ed002')
             return value
@@ -80,6 +83,9 @@ def process_bind_param(self, value, dialect):
         raise ValueError("Unexpected input type")
 
     def process_result_value(self, value, dialect):
+        if value is None:
+            return None
+
         return TypeID.from_uuid(value, self.prefix)
 
     # def coerce_compared_value(self, op, value):

test/typeid_test.py

@@ -8,6 +8,8 @@
 
 from activemodel import BaseModel
 from activemodel.mixins import TypeIDMixin
+from activemodel.types.typeid import TypeIDType
+from sqlmodel import Relationship
 
 
 def test_enforces_unique_prefixes():
@@ -25,10 +27,15 @@ def test_no_empty_prefixes_test():
 TYPEID_PREFIX = "myid"
 
 
-class ExampleWithId(BaseModel, TypeIDMixin(TYPEID_PREFIX), table=True):
+class AnotherExample(BaseModel, TypeIDMixin("myotherid"), table=True):
     pass
 
 
+class ExampleWithId(BaseModel, TypeIDMixin(TYPEID_PREFIX), table=True):
+    another_example_id: TypeIDType = AnotherExample.foreign_key(nullable=True)
+    another_example: AnotherExample = Relationship()
+
+
 def test_get_through_prefixed_uid():
     type_uid = TypeID(prefix=TYPEID_PREFIX)
 
@@ -88,3 +95,10 @@ def test_render_typeid(create_and_wipe_database):
     assert json.loads(wrapped_example.model_dump_json())["example"]["id"] == str(
         example.id
     )
+
+
+def test_json_schema(create_and_wipe_database):
+    "json schema generation shouldn't be meaningfully different than json rendering, but let's check it anyway"
+
+    example = ExampleWithId().save()
+    example.model_json_schema()