[英]Using `serde::Serialize` with `Option<chrono::DateTime>`
When trying to serializeOption<chrono::DateTime<Utc>>
I'm encountering an error:尝试序列化Option<chrono::DateTime<Utc>>
时遇到错误:
error[E0308]: mismatched types
--> src/main.rs:39:14
|
39 | #[derive(Serialize, Debug)]
| ^^^^^^^^^ expected struct `DateTime`, found enum `std::option::Option`
|
= note: expected reference `&DateTime<Utc>`
found reference `&'__a std::option::Option<DateTime<Utc>>`
= note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info)
Code ( Playground ):代码( 游乐场):
use chrono::{serde::ts_seconds, DateTime, NaiveDate, Utc};
use serde::Serialize;
fn main() {
let test_struct = TestStruct {
a: 2.45,
date: Some(DateTime::from_utc(
NaiveDate::from_ymd(2000, 1, 1).and_hms(1, 1, 1),
Utc,
)),
};
let string = serde_json::to_string(&test_struct).unwrap();
println!("default: {}", string);
#[derive(Serialize, Debug)]
struct TestStruct {
pub a: f32,
#[serde(with = "ts_seconds")]
pub date: Option<DateTime<Utc>>,
}
}
Looking at chrono::ts_seconds
and serde_with I have no idea where to move forward here.看着chrono::ts_seconds
和serde_with我不知道该往哪里前进。
I would really appreciate any help with this.我真的很感激任何帮助。
Chrono already has a function for Option<DateTime<Utc>>
, namely chrono::serde::ts_seconds_option
. Chrono 已经有一个 function 用于Option<DateTime<Utc>>
,即chrono::serde::ts_seconds_option
。
#[derive(Serialize, Debug)]
struct TestStruct {
pub a: f32,
#[serde(with = "ts_seconds_option")]
pub date: Option<DateTime<Utc>>,
}
The solution with serde_with
looks like this:使用serde_with
的解决方案如下所示:
#[serde_as]
#[derive(Serialize, Debug)]
struct TestStruct {
pub a: f32,
#[serde_as(as = "Option<DurationSeconds<i64>>")]
pub date: Option<DateTime<Utc>>,
}
You can write your own wrapper and combine it with serialize_with
and skip_serializing_if
:您可以编写自己的包装器并将其与serialize_with
和skip_serializing_if
结合使用:
pub fn serialize_dt<S>(
dt: &Option<DateTime<Utc>>,
serializer: S
) -> Result<S::Ok, S::Error>
where
S: Serializer {
match dt {
Some(dt) => ts_seconds::serialize(dt, serializer),
_ => unreachable!(),
}
}
#[derive(Serialize, Debug)]
struct TestStruct {
pub a: f32,
#[serde(serialize_with = "serialize_dt", skip_serializing_if = "Option::is_none")]
pub date: Option<DateTime<Utc>>,
}
For when you want to use DateTime<Utc>
instead of a Unix timestamp.当您想使用DateTime<Utc>
而不是 Unix 时间戳时。
const FORMAT: &str = "%Y-%m-%d %H:%M:%S";
pub fn serialize<S>(date: &Option<DateTime<Utc>>, serializer: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
match date.is_some() {
true => {
let s = format!("{}", date.as_ref().unwrap().format(FORMAT));
serializer.serialize_str(&s)
}
false => serializer.serialize_none(),
}
}
"{\"a\":2.45,\"date\":\"2022-12-16 16:40:36\"}"
TestStruct { a: 2.45, date: Some(2022-12-16T16:40:36Z) }
"{\"a\":2.45,\"date\":null}"
TestStruct { a: 2.45, date: None }
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