Macro time::serde::format_description

format_description!() { /* proc-macro */ }

Generate a custom serializer and deserializer from the provided string.

The syntax accepted by this macro is the same as format_description::parse(), which can be found in the book.

Usage

Invoked as serde::format_description!(mod_name, Date, "<format string>"). This puts a module named mod_name in the current scope that can be used to format Date structs. A submodule (mod_name::option) is also generated for Option<Date>. Both modules are only visible in the current scope.

The returned Option will contain a deserialized value if present and None if the field is present but the value is null (or the equivalent in other formats). To return None when the field is not present, you should use #[serde(default)] on the field.

Examples

use ::serde::{Serialize, Deserialize};
use time::serde;

// Makes a module `mod my_format { ... }`.
serde::format_description!(my_format, OffsetDateTime, "hour=[hour], minute=[minute]");
#[derive(Serialize, Deserialize)]
struct SerializesWithCustom {
    #[serde(with = "my_format")]
    dt: OffsetDateTime,
    #[serde(with = "my_format::option")]
    maybe_dt: Option<OffsetDateTime>,
}