Skip non-serde fields correctly (#702)

Author: Lxixnxuxs

serde/de.py

@@ -1194,7 +1194,7 @@ def to_iter_arg(f: DeField[T], *args: Any, **kwargs: Any) -> DeField[T]:
 
 
 def renderable(f: DeField[Any]) -> bool:
-    return f.init
+    return f.init and not f.skip
 
 
 jinja2_env = jinja2.Environment(

serde/se.py

@@ -600,24 +600,24 @@ def {{func}}(obj, reuse_instances = None, convert_sets = None, skip_none = False
 
   res = {}
   {% for f in fields -%}
-  subres = {{rvalue(f)}}
   {% if not f.skip -%}
-    {% if lvalue(f) == '__FLATTEN_DICT__' -%}
+  subres = {{rvalue(f)}}
+  {% if lvalue(f) == '__FLATTEN_DICT__' -%}
   # Merge flattened dict into result (declared fields take precedence)
   if subres:
     for __k, __v in subres.items():
       if __k not in res:
         res[__k] = __v
-    {% elif f.skip_if -%}
+  {% elif f.skip_if -%}
   if not {{f.skip_if.name}}(subres):
     {{lvalue(f)}} = subres
-    {% else -%}
+  {% else -%}
   if skip_none:
     if subres is not None:
       {{lvalue(f)}} = subres
   else:
     {{lvalue(f)}} = subres
-    {% endif -%}
+  {% endif -%}
   {% endif %}
 
   {% endfor -%}

tests/test_basics.py

@@ -780,6 +780,47 @@ class Foo:
     assert str(ex.value).startswith("Unsupported type: UnsupportedClass")
 
 
+def test_skip_with_unsupported_types() -> None:
+    class UnsupportedClass:
+        """A class that is NOT decorated with @serde."""
+
+        def __init__(self, value: int = 42) -> None:
+            self.value = value
+
+    # Decoration should succeed
+    @serde.serde
+    class Foo:
+        name: str
+        internal: UnsupportedClass = serde.field(default_factory=UnsupportedClass, skip=True)
+
+    # Serialization should work
+    f = Foo(name="test")
+    assert serde.to_dict(f) == {"name": "test"}
+
+    # Deserialization should work, using default for skipped field
+    restored = serde.from_dict(Foo, {"name": "test"})
+    assert restored.name == "test"
+    assert isinstance(restored.internal, UnsupportedClass)
+
+    # Also test with List of unsupported types
+    @serde.serde
+    class Bar:
+        name: str
+        items: list[UnsupportedClass] = serde.field(default_factory=list, skip=True)
+
+    b = Bar(name="test")
+    b.items.append(UnsupportedClass(1))
+    b.items.append(UnsupportedClass(2))
+
+    # Serialization should work even with non-empty list
+    assert serde.to_dict(b) == {"name": "test"}
+
+    # Deserialization should work
+    restored_bar = serde.from_dict(Bar, {"name": "test"})
+    assert restored_bar.name == "test"
+    assert restored_bar.items == []
+
+
 def test_dataclass_inheritance() -> None:
     @serde.serde
     class Base: