小编a_d*_*zle的帖子

我在尝试创建 Diesel 默认情况下未实现的自定义类型时遇到了以下代码的U128困难u128。我的目标是将原u128语作为文本格式或数字（最好是数字）存储在 Postgresql 数据库中。

use std::io::Write;
use diesel::{AsExpression, deserialize, FromSqlRow, serialize};
use diesel::deserialize::{FromSql};
use diesel::pg::{Pg};
use diesel::serialize::{IsNull, Output, ToSql};
use diesel::sql_types::{Text};

#[derive(AsExpression, FromSqlRow, Debug, Clone, Copy)]
#[diesel(sql_type = Text)]
pub struct U128(pub u128);

impl ToSql<Text, Pg> for U128 {
    fn to_sql<'b>(&self, out: &mut Output<'b, '_, Pg>) -> serialize::Result {
        write!(out, "{}", self.0.to_string())?;
        Ok(IsNull::No)
    }
}

impl FromSql<Text, Pg> for U128 {
    fn from_sql(bytes: Option<&[u8]>) -> deserialize::Result<Self> {
        let s = String::from_utf8_lossy(bytes.as_bytes());
        Ok(U128(s.parse()?))
    } …