Make round trip exclude computed fields (#934)

Author: dmontagu

src/serializers/computed_fields.rs

@@ -48,6 +48,10 @@ impl ComputedFields {
         exclude: Option<&PyAny>,
         extra: &Extra,
     ) -> PyResult<()> {
+        if extra.round_trip {
+            // Do not serialize computed fields
+            return Ok(());
+        }
         for computed_fields in &self.0 {
             computed_fields.to_python(model, output_dict, filter, include, exclude, extra)?;
         }
@@ -63,6 +67,10 @@ impl ComputedFields {
         exclude: Option<&PyAny>,
         extra: &Extra,
     ) -> Result<(), S::Error> {
+        if extra.round_trip {
+            // Do not serialize computed fields
+            return Ok(());
+        }
         for computed_field in &self.0 {
             let property_name_py = computed_field.property_name_py.as_ref(model.py());
             if let Some((next_include, next_exclude)) = filter

tests/serializers/test_model.py

@@ -570,6 +570,9 @@ def area(self) -> bytes:
     assert s.to_python(Model(width=3, height=4), mode='json') == {'width': 3, 'height': 4, 'area': '12'}
     assert s.to_json(Model(width=3, height=4)) == b'{"width":3,"height":4,"area":"12"}'
 
+    assert s.to_python(Model(width=3, height=4), round_trip=True) == {'width': 3, 'height': 4}
+    assert s.to_json(Model(width=3, height=4), round_trip=True) == b'{"width":3,"height":4}'
+
 
 def test_property_alias():
     @dataclasses.dataclass