Require 'Dict' annotations to have types

CHANGELOG.md

@@ -1,3 +1,7 @@
+# 0.11.1 (2020-09-12)
+
+- Fixed error message for `Dict` annotations lacking types.
+
 # 0.11 (2020-09-10)
 
 - Added support to treat `Mapping` type annotations as dictionaries.

datafiles/converters/__init__.py

@@ -70,8 +70,14 @@ def map_type(cls, *, name: str = '', item_cls: Optional[type] = None):
                 value = map_type(item_cls)
             else:
                 log.warn("Schema enforcement not possible with 'Dict' annotation")
-                key = map_type(cls.__args__[0])
-                value = map_type(cls.__args__[1])
+                try:
+                    key = map_type(cls.__args__[0])
+                    value = map_type(cls.__args__[1])
+                except TypeError as e:
+                    assert '~' in str(e), f'Unhandled error: ' + str(e)
+                    raise TypeError(
+                        "Types are required with 'Dict' annotation"
+                    ) from None
 
             converter = Dictionary.of_mapping(key, value)
 

datafiles/tests/test_converters.py

@@ -66,6 +66,10 @@ def it_handles_dict_annotations(expect):
         converter = converters.map_type(Dict[str, int])
         expect(converter.__name__) == 'StringIntegerDict'
 
+    def it_requires_dict_annotations_to_have_types(expect):
+        with expect.raises(TypeError, "Types are required with 'Dict' annotation"):
+            converters.map_type(Dict)
+
     def it_handles_abstract_mapping_types(expect):
         converter = converters.map_type(Mapping[str, int])
         expect(converter.__name__) == 'StringIntegerDict'

docs/requirements.txt

@@ -1,2 +1,2 @@
 mkdocs==1.0.4
-Pygments==2.6.1
+Pygments==2.7.0

pyproject.toml

@@ -1,7 +1,7 @@
 [tool.poetry]
 
 name = "datafiles"
-version = "0.11"
+version = "0.11.1"
 description = "File-based ORM for dataclasses."
 
 license = "MIT"