Fix NiklasRosenstein#66: dataclass from Generic now serializes

.changelog/_unreleased.toml

@@ -0,0 +1,5 @@
+[[entries]]
+id = "693674ea-b2b2-4733-bce6-4d5bae59b164"
+type = "fix"
+description = "Fix #66: dataclasses inheriting from uninstantiated Generic did not get all their fields serialized"
+author = "@rhaps0dy"

databind/src/databind/core/schema.py

@@ -245,7 +245,7 @@ class A(Generic[T]):
             pass
 
         # Continue with the base classes.
-        for base in hint.bases or hint.type.__bases__:
+        for base in (*hint.bases, *hint.type.__bases__):
             base_hint = TypeHint(base, source=hint.type).evaluate().parameterize(parameter_map)
             assert isinstance(base_hint, ClassTypeHint), f"nani? {base_hint}"
             if dataclasses.is_dataclass(base_hint.type):

databind/src/databind/core/tests/schema_test.py

@@ -456,3 +456,25 @@ def test_parse_dataclass_with_forward_ref() -> None:
         ClassWithForwardRef,
         ClassWithForwardRef,
     )
+
+T = t.TypeVar("T")
+
+@dataclasses.dataclass
+class GenericClass(t.Generic[T]):
+    a_field: int
+
+
+@dataclasses.dataclass
+class InheritGeneric(GenericClass):
+    b_field: str
+
+
+def test_schema_generic_dataclass() -> None:
+    """Regression test for #66: dataclasses inheriting from Generic with an uninstantiated TypeVar don't get their
+    parents' fields.
+    """
+    assert convert_dataclass_to_schema(InheritGeneric) == Schema(
+        {"a_field": Field(TypeHint(int), True), "b_field": Field(TypeHint(str), True)},
+        InheritGeneric,
+        InheritGeneric,
+    )

databind/src/databind/json/tests/converters_test.py

@@ -713,3 +713,25 @@ def of(cls, v: str) -> "MyCls":
     mapper = make_mapper([JsonConverterSupport()])
     assert mapper.serialize(MyCls(), MyCls) == "MyCls"
     assert mapper.deserialize("MyCls", MyCls) == MyCls()
+
+
+T = t.TypeVar("T")
+
+
+@dataclasses.dataclass
+class GenericClass(t.Generic[T]):
+    a_field: int
+
+
+@dataclasses.dataclass
+class InheritGeneric(GenericClass):
+    b_field: str
+
+
+def test_serialize_generic_dataclass() -> None:
+    """Regression test for #66: dataclasses inheriting from Generic with an uninstantiated TypeVar don't get their
+    parents' fields.
+    """
+    obj = InheritGeneric(2, "hi")
+    mapper = make_mapper([SchemaConverter(), PlainDatatypeConverter()])
+    assert mapper.serialize(obj, InheritGeneric) == {"a_field": obj.a_field, "b_field": obj.b_field}