Fixes [302](#302)

src/sqlacodegen/generators.py

@@ -1362,15 +1362,18 @@ def generate_base(self) -> None:
         self.base = Base(
             literal_imports=[],
             declarations=[],
-            metadata_ref="",
+            metadata_ref="metadata",
+            table_metadata_declaration="metadata = MetaData()",
         )
 
     def collect_imports(self, models: Iterable[Model]) -> None:
         super(DeclarativeGenerator, self).collect_imports(models)
+        if any(isinstance(model, Model) for model in models):
+            self.add_literal_import("sqlalchemy", "MetaData")
         if any(isinstance(model, ModelClass) for model in models):
-            self.remove_literal_import("sqlalchemy", "MetaData")
             self.add_literal_import("sqlmodel", "SQLModel")
             self.add_literal_import("sqlmodel", "Field")
+            self.add_literal_import("sqlalchemy.orm", "mapped_column")
 
     def collect_imports_for_model(self, model: Model) -> None:
         super(DeclarativeGenerator, self).collect_imports_for_model(model)

tests/test_cli.py

@@ -139,13 +139,14 @@ def test_cli_sqlmodels(db_path: Path, tmp_path: Path) -> None:
         == """\
 from typing import Optional
 
-from sqlalchemy import Column, Integer, Text
+from sqlalchemy import Integer, MetaData, Text
+from sqlalchemy.orm import mapped_column
 from sqlmodel import Field, SQLModel
 
 class Foo(SQLModel, table=True):
-    id: Optional[int] = Field(default=None, sa_column=Column('id', Integer, \
+    id: Optional[int] = Field(default=None, sa_column=mapped_column('id', Integer, \
 primary_key=True))
-    name: str = Field(sa_column=Column('name', Text, nullable=False))
+    name: str = Field(sa_column=mapped_column('name', Text))
 """
     )