Fix dataclass initialization (dfurtado#48)

* Fix dataclass initialization

Fix the dataclass initialization so the order of the members of the dataclass doesn't need to match the order of the columns in the CSV file. That adds flexibility when non-required fields with default values needs to be defined last in the dataclass.

Author: dfurtado

dataclass_csv/dataclass_reader.py

@@ -178,7 +178,7 @@ def _parse_date_value(self, field, date_value):
         return datetime.strptime(date_value, dateformat)
 
     def _process_row(self, row):
-        values = []
+        values = dict()
 
         for field in dataclasses.fields(self._cls):
             if not field.init:
@@ -190,7 +190,7 @@ def _process_row(self, row):
                 raise CsvValueError(ex, line_number=self._reader.line_num) from None
 
             if not value and field.default is None:
-                values.append(None)
+                values[field.name] = None
                 continue
 
             field_type = self.type_hints[field.name]
@@ -206,7 +206,7 @@ def _process_row(self, row):
                 except ValueError as ex:
                     raise CsvValueError(ex, line_number=self._reader.line_num) from None
                 else:
-                    values.append(transformed_value)
+                    values[field.name] = transformed_value
                     continue
 
             if field_type is bool:
@@ -219,7 +219,7 @@ def _process_row(self, row):
                 except ValueError as ex:
                     raise CsvValueError(ex, line_number=self._reader.line_num) from None
                 else:
-                    values.append(transformed_value)
+                    values[field.name] = transformed_value
                     continue
 
             try:
@@ -233,8 +233,8 @@ def _process_row(self, row):
                     line_number=self._reader.line_num,
                 ) from e
             else:
-                values.append(transformed_value)
-        return self._cls(*values)
+                values[field.name] = transformed_value
+        return self._cls(**values)
 
     def __next__(self):
         row = next(self._reader)

tests/mocks.py

@@ -122,3 +122,9 @@ class UserWithSSN:
 class UserWithEmail:
     name: str
     email: str
+
+
+@dataclasses.dataclass
+class UserWithOptionalEmail:
+    name: str
+    email: str = "not specified"

tests/test_dataclass_reader.py

@@ -15,6 +15,7 @@
     UserWithSSN,
     SSN,
     UserWithEmail,
+    UserWithOptionalEmail,
 )
 
 
@@ -248,3 +249,36 @@ def test_skip_header_validation(create_csv):
     with csv_file.open() as f:
         reader = DataclassReader(f, UserWithEmail, validate_header=False)
         list(reader)
+
+
+def test_dt_different_order_as_csv(create_csv):
+    csv_file = create_csv(
+        {"email": "[email protected]", "name": "User1"},
+        fieldnames=[
+            "email",
+            "name",
+        ],
+    )
+
+    with csv_file.open() as f:
+        reader = DataclassReader(f, UserWithEmail)
+        list(reader)
+
+
+def test_dt_different_order_as_csv_and_option_field(create_csv):
+    data = [
+        {"email": "[email protected]", "name": "User1"},
+        {"name": "User1"},
+    ]
+
+    csv_file = create_csv(
+        data,
+        fieldnames=[
+            "email",
+            "name",
+        ],
+    )
+
+    with csv_file.open() as f:
+        reader = DataclassReader(f, UserWithOptionalEmail)
+        list(reader)

tests/test_decorators.py

@@ -14,70 +14,70 @@
 
 
 def test_should_raise_error_without_dateformat(create_csv):
-    csv_file = create_csv({'name': 'Test', 'create_date': '2018-12-09'})
+    csv_file = create_csv({"name": "Test", "create_date": "2018-12-09"})
 
-    with csv_file.open('r') as f:
+    with csv_file.open("r") as f:
         with pytest.raises(AttributeError):
             reader = DataclassReader(f, UserWithoutDateFormatDecorator)
             list(reader)
 
 
 def test_shold_not_raise_error_when_using_dateformat_decorator(create_csv):
-    csv_file = create_csv({'name': 'Test', 'create_date': '2018-12-09'})
+    csv_file = create_csv({"name": "Test", "create_date": "2018-12-09"})
 
-    with csv_file.open('r') as f:
+    with csv_file.open("r") as f:
         reader = DataclassReader(f, UserWithDateFormatDecorator)
         list(reader)
 
 
 def test_shold_not_raise_error_when_dateformat_metadata(create_csv):
-    csv_file = create_csv({'name': 'Test', 'create_date': '2018-12-09'})
+    csv_file = create_csv({"name": "Test", "create_date": "2018-12-09"})
 
-    with csv_file.open('r') as f:
+    with csv_file.open("r") as f:
         reader = DataclassReader(f, UserWithDateFormatMetadata)
         list(reader)
 
 
 def test_use_decorator_when_metadata_is_not_defined(create_csv):
     csv_file = create_csv(
         {
-            'name': 'Test',
-            'birthday': '1977-08-26',
-            'create_date': '2018-12-09 11:11',
+            "name": "Test",
+            "birthday": "1977-08-26",
+            "create_date": "2018-12-09 11:11",
         }
     )
 
-    with csv_file.open('r') as f:
+    with csv_file.open("r") as f:
         reader = DataclassReader(f, UserWithDateFormatDecoratorAndMetadata)
         list(reader)
 
 
 def test_should_raise_error_when_value_is_whitespaces(create_csv):
-    csv_file = create_csv({'name': '     '})
+    csv_file = create_csv({"name": "     "})
 
-    with csv_file.open('r') as f:
+    with csv_file.open("r") as f:
         with pytest.raises(CsvValueError):
             reader = DataclassReader(f, UserWithoutAcceptWhiteSpacesDecorator)
             list(reader)
 
 
 def test_should_not_raise_error_when_value_is_whitespaces(create_csv):
-    csv_file = create_csv({'name': '     '})
+    csv_file = create_csv({"name": "     "})
 
-    with csv_file.open('r') as f:
+    with csv_file.open("r") as f:
         reader = DataclassReader(f, UserWithAcceptWhiteSpacesDecorator)
         data = list(reader)
 
         user = data[0]
-        assert user.name == '     '
+        assert user.name == "     "
 
 
 def test_should_not_raise_error_when_using_meta_accept_whitespaces(create_csv):
-    csv_file = create_csv({'name': '     '})
+    csv_file = create_csv({"name": "     "})
 
-    with csv_file.open('r') as f:
+    with csv_file.open("r") as f:
         reader = DataclassReader(f, UserWithAcceptWhiteSpacesMetadata)
         data = list(reader)
 
         user = data[0]
-        assert user.name == '     '
+        assert user.name == "     "