Allow all types to be used in field mapping

CHANGELOG.rst

@@ -1,5 +1,13 @@
+1.2.0, TBD
+----------
+Features & fixes:
+
+* Allow all types, including special forms, to be used in ``serializer_field_mapping``.
+
 1.1.1, 25 January 2021
 ----------------------
+Features & fixes:
+
 * Fix usage of PEP 585 generics with forward references (e.g. ``list["str"]``).
 * Fix usage of ``allow_empty`` with ``many=True``.
 

rest_framework_dataclasses/field_utils.py

@@ -89,6 +89,10 @@ def get_relation_info(type_info: TypeInfo) -> RelationInfo:
 
 
 def lookup_type_in_mapping(mapping: typing.Dict[type, T], key: type) -> T:
+    # Allow all types, including special forms, to be used when they're present in the mapping
+    if key in mapping:
+        return mapping[key]
+
     try:
         # _SpecialForm types like Literal, NoReturn don't have an __mro__ attribute
         bases = inspect.getmro(key)

tests/test_field_utils.py

@@ -0,0 +1,25 @@
+import unittest
+import typing
+
+from rest_framework_dataclasses import field_utils
+from rest_framework_dataclasses.types import Literal
+
+
+class FieldUtilsTest(unittest.TestCase):
+    def test_lookup_type(self):
+        mapping = {
+            str: 1,
+            int: 2,
+            typing.Union[int, str]: 3
+        }
+
+        self.assertEqual(field_utils.lookup_type_in_mapping(mapping, str), 1)
+        self.assertEqual(field_utils.lookup_type_in_mapping(mapping, int), 2)
+        self.assertEqual(field_utils.lookup_type_in_mapping(mapping, typing.Union[int, str]), 3)
+
+        self.assertEqual(field_utils.lookup_type_in_mapping(mapping, type('email', (str, ), {})), 1)
+
+        with self.assertRaises(KeyError):
+            field_utils.lookup_type_in_mapping(mapping, float)
+        with self.assertRaises(KeyError):
+            field_utils.lookup_type_in_mapping(mapping, Literal['a', 'b'])