feat(converters)!: Implement converter for single-attribute objects (…

…#11)

cryptodatahub/common/types.py

@@ -60,6 +60,31 @@ def convert_dict_to_object(object_type):
     return _DictObjectConverter(object_type)
 
 
+@attr.s(repr=False, slots=True, hash=True)
+class _ValueToObjectConverter(_ConverterBase):
+    object_type = attr.ib(validator=attr.validators.instance_of(type))
+    value_converter = attr.ib(validator=attr.validators.optional(attr.validators.instance_of(_ConverterBase)))
+
+    def __call__(self, value):
+        if value is None:
+            return None
+
+        if isinstance(value, self.object_type):
+            return value
+
+        if self.value_converter is not None:
+            value = self.value_converter(value)
+
+        return self.object_type(value)
+
+    def __repr__(self):
+        return '<value to object converter>'
+
+
+def convert_value_to_object(object_type, value_converter=None):
+    return _ValueToObjectConverter(object_type, value_converter)
+
+
 @attr.s(repr=False, slots=True, hash=True)
 class _EnumConverter(_ConverterBase):
     enum_type = attr.ib(validator=attr.validators.instance_of(type))

test/common/test_types.py

@@ -45,6 +45,7 @@
     convert_mapping,
     convert_url,
     convert_variadic,
+    convert_value_to_object,
 )
 
 
@@ -194,6 +195,25 @@ def test_repr(self):
         self.assertEqual(repr(convert_dict_to_object(str)), '<dict to object converter>')
 
 
+class TestValueToObjectConverter(unittest.TestCase):
+    def test_none(self):
+        converted_value = convert_value_to_object(TestJsonObjectComplex)(None)
+        self.assertEqual(converted_value, None)
+
+    def test_convert_object_class(self):
+        original_value = TestJsonObjectComplex('value')
+        converted_value = convert_value_to_object(TestJsonObjectComplex)(original_value)
+        self.assertEqual(original_value, converted_value)
+
+    def test_convert_converter(self):
+        original_value = '1970-01-01'
+        converted_value = convert_value_to_object(TestJsonObjectComplex, convert_datetime())(original_value)
+        self.assertEqual(converted_value.attr, datetime.datetime(1970, 1, 1, 0, 0))
+
+    def test_repr(self):
+        self.assertEqual(repr(convert_value_to_object(str)), '<value to object converter>')
+
+
 class TestBigNumberConverter(unittest.TestCase):
     def test_error_invalid_type(self):
         original_value = 1234