Rust Postgres Diesel Timestamptz support with async-graphql

gqltimestamptz.rs

use std::io::Write;

use async_graphql::{InputValueError, InputValueResult, Scalar, ScalarType, Value};
use diesel::{
    deserialize,
    pg::Pg,
    serialize::{self, Output},
    sql_types::{self, Timestamp, Timestamptz},
    types::{FromSql, ToSql},
};

#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, FromSqlRow, AsExpression)]
#[sql_type = "Timestamp"]
#[sql_type = "Timestamptz"]
/// Timestamps are represented in Postgres as a 64 bit signed integer representing the number of
/// microseconds since January 1st 2000. This struct is a dumb wrapper type, meant only to indicate
/// the integer's meaning.
pub struct GqlTimestamptz(pub i64);

#[Scalar]
impl ScalarType for GqlTimestamptz {
    fn parse(value: Value) -> InputValueResult<Self> {
        if let Value::String(value) = &value {
            // Parse the integer value
            Ok(value.parse().map(GqlTimestamptz)?)
        } else {
            // If the type does not match
            Err(InputValueError::expected_type(value))
        }
    }

    fn to_value(&self) -> Value {
        Value::Number(self.0.into())
    }
}

impl ToSql<sql_types::Timestamp, Pg> for GqlTimestamptz {
    fn to_sql<W: Write>(&self, out: &mut Output<W, Pg>) -> serialize::Result {
        ToSql::<sql_types::BigInt, Pg>::to_sql(&self.0, out)
    }
}

impl FromSql<sql_types::Timestamp, Pg> for GqlTimestamptz {
    fn from_sql(bytes: Option<&[u8]>) -> deserialize::Result<Self> {
        FromSql::<sql_types::BigInt, Pg>::from_sql(bytes).map(GqlTimestamptz)
    }
}

impl ToSql<sql_types::Timestamptz, Pg> for GqlTimestamptz {
    fn to_sql<W: Write>(&self, out: &mut Output<W, Pg>) -> serialize::Result {
        ToSql::<sql_types::Timestamp, Pg>::to_sql(self, out)
    }
}

impl FromSql<sql_types::Timestamptz, Pg> for GqlTimestamptz {
    fn from_sql(bytes: Option<&[u8]>) -> deserialize::Result<Self> {
        FromSql::<sql_types::Timestamp, Pg>::from_sql(bytes)
    }
}