diff --git a/django2pydantic/getter.py b/django2pydantic/getter.py
index d966a06..d177ca2 100644
--- a/django2pydantic/getter.py
+++ b/django2pydantic/getter.py
@@ -58,6 +58,10 @@ def _get_prefetched_values(self, key: str) -> Result:
             if k.startswith(f"{key}__"):
                 values[k[len(key) + 2 :]] = v
 
+        # If values is empty, bubble up AttributeError as there's no value for the key
+        if not values:
+            raise AttributeError(key)
+
         return values
 
     def __init__(self, obj: Any, schema_cls: Any, context: Any = None) -> None:
diff --git a/django2pydantic/mixin.py b/django2pydantic/mixin.py
index 1a480fe..825806d 100644
--- a/django2pydantic/mixin.py
+++ b/django2pydantic/mixin.py
@@ -18,7 +18,7 @@ class BaseMixins(BaseModel):
         "from_attributes": True,
         "arbitrary_types_allowed": True,
         "use_enum_values": True,
-        "validate_default": True,
+        "validate_default": False,
     }
 
     @model_validator(mode="wrap")