Setting result error using py_sql with single result

[SnowyThinker]

#[py_sql("select ROUND(IFNULL(AVG(level), 0)) from rating WHERE id = #{id}  ")]
async fn query_rating_by_app(rb: &RBatis, id: usize) -> usize { impled!() }

called Result::unwrap() on an Err value: E("error while decoding value: invalid type: map, expected usize")

[zhuxiujia]

select ROUND return an float value(just like 1.0)
so,you should change to type f64

#[py_sql("select ROUND(IFNULL(AVG(level), 0)) from rating WHERE id = #{id}  ")]
async fn query_rating_by_app(rb: &RBatis, id: usize) -> f64{ impled!() }