fix lint

sqlmodel/_compat.py

@@ -22,6 +22,7 @@ from pydantic import VERSION as P_VERSION
 from pydantic import BaseModel
 from pydantic.fields import FieldInfo
 from sqlalchemy import inspect
+from sqlalchemy.orm import Mapper
 from typing_extensions import Annotated, get_args, get_origin
 
 # Reassign variable to make it reexported for mypy
@@ -293,20 +294,21 @@ if IS_PYDANTIC_V2:
         # End SQLModel override
         # Override polymorphic_on default value
         mapper = inspect(cls)
-        polymorphic_on = mapper.polymorphic_on
-        if polymorphic_on is not None:
-            polymorphic_property = mapper.get_property_by_column(polymorphic_on)
-            field_info = cls.model_fields.get(polymorphic_property.key)
-            if field_info:
-                v = values.get(polymorphic_property.key)
-                # if model is inherited or polymorphic_on is not explicitly set
-                # set the polymorphic_on by default
-                if mapper.inherits or v is None:
-                    setattr(
-                        self_instance,
-                        polymorphic_property.key,
-                        mapper.polymorphic_identity,
-                    )
+        if isinstance(mapper, Mapper):
+            polymorphic_on = mapper.polymorphic_on
+            if polymorphic_on is not None:
+                polymorphic_property = mapper.get_property_by_column(polymorphic_on)
+                field_info = cls.model_fields.get(polymorphic_property.key)
+                if field_info:
+                    v = values.get(polymorphic_property.key)
+                    # if model is inherited or polymorphic_on is not explicitly set
+                    # set the polymorphic_on by default
+                    if mapper.inherits or v is None:
+                        setattr(
+                            self_instance,
+                            polymorphic_property.key,
+                            mapper.polymorphic_identity,
+                        )
         return self_instance
 
     def sqlmodel_validate(

sqlmodel/main.py

@@ -551,9 +551,10 @@ class SQLModelMetaclass(ModelMetaclass, DeclarativeMeta):
         for base in bases[::-1]:
             if issubclass(base, BaseModel):
                 base_fields.update(base.model_fields)
-        for k, v in new_cls.model_fields.items():
+        fields = get_model_fields(new_cls)
+        for k, v in fields.items():
             if isinstance(v.default, InstrumentedAttribute):
-                new_cls.model_fields[k] = base_fields.get(k)
+                fields[k] = base_fields.get(k, FieldInfo())
 
         def get_config(name: str) -> Any:
             config_class_value = get_config_value(
@@ -572,7 +573,7 @@ class SQLModelMetaclass(ModelMetaclass, DeclarativeMeta):
             # or if __tablename__ is in __annotations__. Only set __tablename__ if it's
             # a table model
             if new_cls.__name__ != "SQLModel" and not hasattr(new_cls, "__tablename__"):
-                new_cls.__tablename__ = new_cls.__name__.lower()
+                setattr(new_cls, "__tablename__", new_cls.__name__.lower())  # noqa: B010
             # If it was passed by kwargs, ensure it's also set in config
             set_config_value(model=new_cls, parameter="table", value=config_table)
             for k, v in get_model_fields(new_cls).items():
@@ -731,7 +732,7 @@ def get_sqlalchemy_type(field: Any) -> Any:
     raise ValueError(f"{type_} has no matching SQLAlchemy type")
 
 
-def get_column_from_field(field: Any) -> Column:  # type: ignore
+def get_column_from_field(field: Any) -> Column | MappedColumn:  # type: ignore
     if IS_PYDANTIC_V2:
         field_info = field
     else: