Is time::serde::format_description well documented?

[ogarcia]

I am trying to do what this documentation says to set the iso8601 to four digits instead of six.

My code is quite simple. The only peculiarity is that I use serde re-exported from rocket to avoid versioning problems.

use rocket::serde::{Deserialize, Serialize};
use time::OffsetDateTime;
use time::format_description::well_known::{iso8601, Iso8601};

const CONFIG: iso8601::EncodedConfig = iso8601::Config::DEFAULT
    .set_year_is_six_digits(false)
    .encode();
const FORMAT: Iso8601<CONFIG> = Iso8601::<CONFIG>;
time::serde::format_description!(my_format, OffsetDateTime, FORMAT);

#[derive(Clone, Debug, Deserialize, Serialize)]
#[serde(crate = "rocket::serde")]
pub struct LesmaMeta {
    pub hash: String,
    pub password: Option<String>,
    pub name: String,
    pub binary: bool,
    pub limit: u8,
    pub current: u8,
    #[serde(with = "my_format")]
    pub create: OffsetDateTime,
    #[serde(with = "my_format")]
    pub expire: OffsetDateTime
}

If I run this I get the following error:

error[E0432]: unresolved import `serde`
 --> src/main.rs:9:1
  |
9 | time::serde::format_description!(my_format, OffsetDateTime, FORMAT);
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: a similar path exists: `time::serde`
  |
  = note: this error originates in the macro `time::serde::format_description` (in Nightly builds, run with -Z macro-backtrace for more info)

error[E0433]: failed to resolve: could not find `serde` in the list of imported crates
 --> src/main.rs:9:1
  |
9 | time::serde::format_description!(my_format, OffsetDateTime, FORMAT);
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ could not find `serde` in the list of imported crates
  |
  = note: this error originates in the macro `time::serde::format_description` (in Nightly builds, run with -Z macro-backtrace for more info)

Possibly the problem is because I'm using the re-exported serde, but I can't figure out how to fix it (or if there is a solution). Any ideas?

[jhpratt]

time requires that serde be a direct dependency, as it uses ::serde to begin paths in the generated code.

[ogarcia]

Do I understand that there is no way to use re-exported serde? Using re-exported serde is not so strange, especially when you want to avoid dependency problems.

[jhpratt]

I'm not certain why you need a lower version of serde, but you have to have it as a direct dependency. There is no way around this at the moment. It's a technical restriction.