Snippet to specify custom date format when using Serde and Chrono

serde_chrono_dateformat.rs

use serde::Deserialize;
use serde_json;
use chrono::{DateTime,Utc,NaiveDateTime,NaiveDate};

#[derive(Debug, Deserialize)]
struct TheStruct {
    #[serde(deserialize_with = "datetime_deserializer")]
    time: DateTime<Utc>,
}

const DATE_FORMAT: &str = "%F %T";

pub fn datetime_deserializer<'de, D>(d: D) -> Result<DateTime<Utc>, D::Error>
where
    D: serde::Deserializer<'de>,
{
    let as_str: &str = Deserialize::deserialize(d)?;
    return NaiveDateTime::parse_from_str(as_str, DATE_FORMAT)
        .map(|dt| DateTime::<Utc>::from_utc(dt, Utc))
        .map_err(|e| { 
            serde::de::Error::custom(format!("Error parting date: {}", e.to_string())) 
        });
}

#[test]
fn test_date_format() {
    let json = r#"{
        "time": "2019-04-01 12:00:00"
    }"#;
    let val: TheStruct = serde_json::from_str(json)
        .expect("failed to parse json");
    let expected = DateTime::<Utc>::from_utc(
        NaiveDate::from_ymd(2019, 4, 1).and_hms(12, 0, 0),
        Utc);
    assert_eq!(val.time, expected);
}