Make field's description interpret as column's comment

Author: eumiro

sqlmodel/main.py

@@ -744,6 +744,9 @@ def get_column_from_field(field: Any) -> Column:  # type: ignore
         "index": index,
         "unique": unique,
     }
+    description = getattr(field_info, "description", Undefined)
+    if description is not Undefined:
+        kwargs["comment"] = description
     sa_default = Undefined
     if field_info.default_factory:
         sa_default = field_info.default_factory

tests/test_field_description.py

@@ -0,0 +1,23 @@
+from pytest import LogCaptureFixture
+from sqlmodel import Field, SQLModel, create_engine
+
+
+def test_sa_column_description(clear_sqlmodel: None, caplog: LogCaptureFixture) -> None:
+    class Team(SQLModel, table=True):
+        id: int = Field(primary_key=True, description="an id")
+        name: str = Field(description="a name")
+        age: int = Field()
+
+    assert Team.model_fields["id"].description == "an id"
+    assert Team.model_fields["name"].description == "a name"
+    assert Team.model_fields["age"].description is None
+
+    engine = create_engine("sqlite://", echo=True)  # TODO: this should go to Postgres
+    SQLModel.metadata.create_all(engine)
+    msgs = []
+    for msg in caplog.messages:
+        if "COMMENT ON COLUMN" in msg:
+            msgs.append(msg)
+    assert len(msgs) == 2
+    assert "COMMENT ON COLUMN team.id IS 'an id'" in msgs[0]
+    assert "COMMENT ON COLUMN team.name IS 'a name'" in msgs[1]