Deserialize "epoch" in milliseconds

[mbergkvist]

I'm deserializing a JSON data where one of the field is a unix timestamp in milliseconds. With chrono I'm using #[serde(deserialize_with = "chrono::serde::ts_milliseconds::deserialize")] but I'm now looking into replacing chrono with time but I can't seem to get the deserializer for time::OffsetDateTime to work. Any hints?

[jhpratt]

What code do you have? I presume you're using a custom deserializer, as there's not one in this library with the exact behavior you're looking for (I imagine you already noticed this).

[mbergkvist]

I was looking for a deserializer and couldn't find one, but I was hoping that it was my search skill that was lacking and not the a ready-to-use-deserializer in time ;-)

Any pointer to start looking if I'm to implement it myself?

[jhpratt]

Probably the best place to look is the source for the timestamp serde implementation. Only slight modifications should be necessary to have it use milliseconds.

[mbergkvist]

Thanks. I'll look into it.

[mbergkvist]

I ended up with a deserializer looking like this

pub(super) fn deserialize<'de, D>(deserializer: D) -> Result<OffsetDateTime, D::Error>
where
    D: Deserializer<'de>,
{
    let ms = i64::deserialize(deserializer)?;
    let sec = ms / 1000;
    OffsetDateTime::from_unix_timestamp(sec)
        .map_err(|err| de::Error::invalid_value(de::Unexpected::Signed(sec), &err))
}