diff --git a/tests/codegen/mappers/test_dict.py b/tests/codegen/mappers/test_dict.py
index f0d5fda4a..f82726c56 100644
--- a/tests/codegen/mappers/test_dict.py
+++ b/tests/codegen/mappers/test_dict.py
@@ -89,13 +89,13 @@ def test_build_class_attribute_from_empty_list(self):
                 AttrTypeFactory.native(DataType.ANY_SIMPLE_TYPE, tag=Tag.ELEMENT),
             ],
         )
-        restrictions = Restrictions(min_occurs=1, max_occurs=sys.maxsize)
+        restrictions = Restrictions(min_occurs=0, max_occurs=sys.maxsize)
         self.assertEqual(expected, target.attrs[0])
         self.assertEqual(restrictions, target.attrs[0].restrictions)
 
     def test_build_class_attribute_from_dict(self):
         target = ClassFactory.create()
-        data = {"sub1": 1, "sub2": "value"}
+        data = {"sub1": 1, "sub2": "value", "sub3": None}
         DictMapper.build_class_attribute(target, "a", data)
 
         expected = AttrFactory.create(
@@ -113,9 +113,14 @@ def test_build_class_attribute_from_dict(self):
             attrs=[
                 AttrFactory.native(DataType.SHORT, name="sub1"),
                 AttrFactory.native(DataType.STRING, name="sub2"),
+                AttrFactory.native(DataType.STRING, name="sub3"),
             ],
         )
 
         self.assertEqual(expected, target.attrs[0])
         self.assertEqual(expected_inner, target.inner[0])
         self.assertEqual(1, len(target.inner))
+
+        self.assertFalse(target.inner[0].attrs[0].restrictions.is_optional)
+        self.assertFalse(target.inner[0].attrs[1].restrictions.is_optional)
+        self.assertTrue(target.inner[0].attrs[2].restrictions.is_optional)
diff --git a/xsdata/codegen/mappers/dict.py b/xsdata/codegen/mappers/dict.py
index 3f5b5cf51..a62be0ba4 100644
--- a/xsdata/codegen/mappers/dict.py
+++ b/xsdata/codegen/mappers/dict.py
@@ -71,4 +71,4 @@ def build_class_attribute(cls, target: Class, name: str, value: Any):
             else:
                 attr_type = cls.build_attr_type(name, value)
 
-            cls.build_attr(target, name, attr_type)
+            cls.build_attr(target, name, attr_type, value=value)
diff --git a/xsdata/codegen/mappers/mixins.py b/xsdata/codegen/mappers/mixins.py
index 59c1d7736..d05002e64 100644
--- a/xsdata/codegen/mappers/mixins.py
+++ b/xsdata/codegen/mappers/mixins.py
@@ -7,6 +7,8 @@
 from xsdata.utils import collections
 from xsdata.utils.namespaces import split_qname
 
+_UNSET = object()
+
 
 class RawDocumentMapper:
     """Mixin class for raw json/xml documents."""
@@ -20,6 +22,7 @@ def build_attr(
         parent_namespace: Optional[str] = None,
         tag: str = Tag.ELEMENT,
         sequence: int = 0,
+        value: Any = _UNSET,
     ):
         """Build an attr for the given class instance.
 
@@ -30,6 +33,7 @@ def build_attr(
             parent_namespace: The parent namespace
             tag: The attr tag
             sequence: The attr sequence number
+            value: The attr sample value
         """
         namespace, name = split_qname(qname)
         namespace = cls.select_namespace(namespace, parent_namespace, tag)
@@ -43,6 +47,10 @@ def build_attr(
 
         attr.restrictions.min_occurs = 1
         attr.restrictions.max_occurs = 1
+
+        if value is None:
+            attr.restrictions.min_occurs = 0
+
         cls.add_attribute(target, attr)
 
     @classmethod