jsonrustserderust-chrono

Unable to deserialize chrono::DateTime from json

I encounter an interesting issue. For some reason serde is unable to deserialize a chrono::DateTime<Utc> object from a string in the same format it was serialized (but it does if I save a variable with it):

use chrono; // 0.4.11
use serde_json; // 1.0.48

fn main() {
    let date = chrono::Utc::now();
    println!("{}", date);

    let date_str = serde_json::to_string(&date).unwrap();
    println!("{}", date_str);

    let parsed_date: chrono::DateTime<chrono::Utc> = serde_json::from_str(&date_str).unwrap();
    println!("{}", parsed_date);

    assert_eq!(date, parsed_date);

    let date = "2020-03-28T16:29:04.644008111Z";
    let _: chrono::DateTime<chrono::Utc> = serde_json::from_str(&date).unwrap();
}

Here is the playground link

Which outputs:

   Compiling playground v0.0.1 (/playground)
    Finished dev [unoptimized + debuginfo] target(s) in 1.01s
     Running `target/debug/playground`
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Error("invalid type: integer `2020`, expected a formatted date and time string or a unix timestamp", line: 1, column: 4)', src/main.rs:17:44
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Standard Output

2020-03-28 17:57:04.222452521 UTC
"2020-03-28T17:57:04.222452521Z"
2020-03-28 17:57:04.222452521 UTC

Why is this happening? How should I be doing it?

Solution

  • You need to put valid json, don't forget double quote:

    let date = "\"2020-03-28T16:29:04.644008111Z\"";

    You can see it with println!("{:?}", date_str);