实现更新和删除方法

有了上一章的基础，我们实现更新和删除方法也不是难事。

实现更新方法

pub(crate) fn update_ts(dm: &DbMeta) -> proc_macro2::TokenStream {
    let field_list = dm.update_fileds();
    let field_list_str = field_list
        .iter()
        .map(|f| format!("{:?} = ", f.to_string()))
        .collect::<Vec<_>>();
    let field_list_com = field_list
        .iter()
        .enumerate()
        .map(|(idx, _)| format!("{}", if idx < field_list.len() - 1 { ", " } else { "" }))
        .collect::<Vec<_>>();

    let table = dm.table.clone();
    let sql = format!("UPDATE {:?} SET ", &table,);
    let pk = dm.pk_ident().clone();
    let pk_str = pk.to_string();

    quote! {
        pub async fn update<'a>(&self, e: impl  ::sqlx::PgExecutor<'a>) -> ::sqlx::Result<u64> {
            let sql = #sql;
            let mut q = ::sqlx::QueryBuilder::new(sql);
            #(
                q.push(#field_list_str)
                .push_bind(&self.#field_list)
                .push(#field_list_com);
            )*

            q.push(format!(" WHERE {} = ", #pk_str)).push_bind(&self.#pk);

            let aff = q.build().execute(e).await?.rows_affected();
            Ok(aff)
        }
    }
}

pub(crate) fn del_ts(dm: &DbMeta) -> proc_macro2::TokenStream {
    let table = dm.table.clone();
    let pk = dm.pk_ident().clone();
    let pk_str = pk.to_string();
    let sql = format!("DELETE FROM {:?} WHERE {:?} = ", &table, &pk_str);

    quote! {
        pub async fn delete<'a>(&self, e: impl  ::sqlx::PgExecutor<'a>) -> ::sqlx::Result<u64> {
            let sql = #sql;
            let mut q = ::sqlx::QueryBuilder::new(sql);
            q.push_bind(&self.#pk);
            let aff = q.build().execute(e).await?.rows_affected();
            Ok(aff)
        }
    }
}