Function columns 

pub fn columns<C: Conventions>(input: TokenStream) -> TokenStream

#[derive(Columns)]: queryweave_sql::Columns for a sqlx entity, recording which column stores each field of the domain model named by #[columns(model = Model)].

Each entity field is a column (named after the field, or its #[sqlx(rename = "...")]) storing the domain field of the same name, or the one named by #[domain_field(name)], which must exist on the domain model. #[sqlx(skip)] and #[sqlx(flatten)] fields are not columns.

Attributes: columns (model = path), domain_field.