How to serialize and deserialize chrono::Duration? - rust

Question

In my current project I'm trying to store a chrono::Duration in a configuration struct, which will be serialized and deserialized occasionally using serde_json.
Unfortunately, it appears that Serialize and Deserialize aren't implemented for chrono::Duration. That said, chrono says it has support for serde via one of its optional features. I tried using this method, but now the compiler is complaining about return methods:
error[E0308]: mismatched types
--> src/config.rs:6:10
|
6 | #[derive(Serialize, Deserialize, Debug, Clone)]
| ^^^^^^^^^ expected struct `DateTime`, found struct `chrono::Duration`
|
= note: expected reference `&DateTime<Utc>`
found reference `&'__a chrono::Duration`
= note: this error originates in the derive macro `Serialize` (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0308]: mismatched types
--> src/config.rs:6:21
|
6 | #[derive(Serialize, Deserialize, Debug, Clone)]
| ^^^^^^^^^^^ expected struct `chrono::Duration`, found struct `DateTime`
|
= note: expected struct `chrono::Duration`
found struct `DateTime<Utc>`
= note: this error originates in the macro `try` (in Nightly builds, run with -Z macro-backtrace for more info)
Why is this happening? What can I do to fix it?
Here's the code in question:
use serde::{Serialize, Deserialize};
use chrono::{DateTime, Duration, Utc};
#[derive(Serialize, Deserialize, Debug, Clone)]
pub struct Config {
pub dest_ip: String,
#[serde(borrow)]
pub include_paths: Vec<&'static std::path::Path>,
pub exclude_paths: Vec<&'static std::path::Path>,
#[serde(with = "chrono::serde::ts_seconds")]
pub time_between_checks: Duration,
}
Also, here's the relevant bits of Cargo.toml:
serde_json = "1.0.72"
serde = { version = "1.0.130", features = ["derive"] }
chrono = { version = "0.4.19", features = ["serde"]}

Answer 1

You can use serde_with::DurationSeconds for serialization. It works identical to ts_seconds but supports more types and serialization forms.
#[serde_with::serde_as]
#[derive(Serialize, Deserialize, Debug, Clone)]
pub struct Config {
// ...
#[serde_as(as = "serde_with::DurationSeconds<i64>")]
pub time_between_checks: Duration,
}