Struct TimestampSecondsWithFrac

pub struct TimestampSecondsWithFrac<FORMAT = f64, STRICTNESS = Strict>(/* private fields */)
where
    FORMAT: Format,
    STRICTNESS: Strictness;

De/Serialize timestamps as seconds since the UNIX epoch

De/serialize timestamps as seconds since the UNIX epoch. Subsecond precision is only supported for TimestampSecondsWithFrac, but not for TimestampSeconds. You can configure the serialization format between integers, floats, and stringified numbers with the FORMAT specifier and configure the deserialization with the STRICTNESS specifier. Serialization of integers will round the timestamp to the nearest value.

The STRICTNESS specifier can either be formats::Strict or formats::Flexible and defaults to formats::Strict. formats::Strict means that deserialization only supports the type given in FORMAT, e.g., if FORMAT is i64 deserialization from a f64 will error. formats::Flexible means that deserialization will perform a best effort to extract the correct timestamp and allows deserialization from any type. For example, deserializing TimestampSeconds<f64, Flexible> will discard any subsecond precision during deserialization from f64 and will parse a String as an integer number.

This type also supports chrono::DateTime and chrono::NaiveDateTime with the chrono-feature flag. This type also supports [time::OffsetDateTime][::time_0_3::OffsetDateTime] and [time::PrimitiveDateTime][::time_0_3::PrimitiveDateTime] with the time_0_3-feature flag.

This table lists the available FORMATs for the different timestamp types. The FORMAT specifier defaults to i64 or f64.

Timestamp Type	Converter	Available FORMATs
std::time::SystemTime	TimestampSeconds	i64, f64, String
std::time::SystemTime	TimestampSecondsWithFrac	f64, String
chrono::DateTime<Utc>	TimestampSeconds	i64, f64, String
chrono::DateTime<Utc>	TimestampSecondsWithFrac	f64, String
chrono::DateTime<Local>	TimestampSeconds	i64, f64, String
chrono::DateTime<Local>	TimestampSecondsWithFrac	f64, String
chrono::NaiveDateTime	TimestampSeconds	i64, f64, String
chrono::NaiveDateTime	TimestampSecondsWithFrac	f64, String
time::OffsetDateTime	TimestampSeconds	i64, f64, String
time::OffsetDateTime	TimestampSecondsWithFrac	f64, String
time::PrimitiveDateTime	TimestampSeconds	i64, f64, String
time::PrimitiveDateTime	TimestampSecondsWithFrac	f64, String

Examples

use std::time::{Duration, SystemTime};

#[serde_as]
#[derive(Deserialize, Serialize)]
struct Timestamps {
    #[serde_as(as = "TimestampSecondsWithFrac<f64>")]
    st_f64: SystemTime,
    #[serde_as(as = "TimestampSecondsWithFrac<String>")]
    st_string: SystemTime,
}

// Serialization
// See how the values get rounded, since subsecond precision is not allowed.

let ts = Timestamps {
    st_f64: SystemTime::UNIX_EPOCH.checked_add(Duration::new(12345, 500_000_000)).unwrap(),
    st_string: SystemTime::UNIX_EPOCH.checked_add(Duration::new(12345, 999_999_000)).unwrap(),
};
// Observe the different data types
let expected = json!({
    "st_f64": 12345.5,
    "st_string": "12345.999999",
});
assert_eq!(expected, serde_json::to_value(ts).unwrap());

// Deserialization works too
// Subsecond precision in numbers will be rounded away

let json = json!({
    "st_f64": 12345.5,
    "st_string": "12345.987654",
});
let expected = Timestamps {
    st_f64: SystemTime::UNIX_EPOCH.checked_add(Duration::new(12345, 500_000_000)).unwrap(),
    st_string: SystemTime::UNIX_EPOCH.checked_add(Duration::new(12345, 987_654_000)).unwrap(),
};
assert_eq!(expected, serde_json::from_value(json).unwrap());

chrono::DateTime<Utc> and chrono::DateTime<Local> are also supported when using the chrono_0_4 feature. Like SystemTime, it is a signed timestamp, thus can be de/serialized as an i64.

use chrono::{DateTime, Local, TimeZone, Utc};

#[serde_as]
#[derive(Deserialize, Serialize)]
struct Timestamps {
    #[serde_as(as = "TimestampSecondsWithFrac<f64>")]
    dt_f64: DateTime<Utc>,
    #[serde_as(as = "TimestampSecondsWithFrac<String>")]
    dt_string: DateTime<Local>,
}

// Serialization

let ts = Timestamps {
    dt_f64: Utc.timestamp_opt(-12345, 500_000_000).unwrap(),
    dt_string: Local.timestamp_opt(12345, 999_999_000).unwrap(),
};
// Observe the different data types
let expected = json!({
    "dt_f64": -12344.5,
    "dt_string": "12345.999999",
});
assert_eq!(expected, serde_json::to_value(ts).unwrap());

// Deserialization works too

let json = json!({
    "dt_f64": -12344.5,
    "dt_string": "12345.987",
});
let expected = Timestamps {
    dt_f64: Utc.timestamp_opt(-12345, 500_000_000).unwrap(),
    dt_string: Local.timestamp_opt(12345, 987_000_000).unwrap(),
};
assert_eq!(expected, serde_json::from_value(json).unwrap());

Trait Implementations

impl<'de> DeserializeAs<'de, SystemTime> for TimestampSecondsWithFrac

fn deserialize_as<D>( deserializer: D, ) -> Result<SystemTime, <D as Deserializer<'de>>::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'de, FORMAT> DeserializeAs<'de, SystemTime> for TimestampSecondsWithFrac<FORMAT, Flexible>

where FORMAT: Format,

fn deserialize_as<D>( deserializer: D, ) -> Result<SystemTime, <D as Deserializer<'de>>::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'de> DeserializeAs<'de, SystemTime> for TimestampSecondsWithFrac<String>

fn deserialize_as<D>( deserializer: D, ) -> Result<SystemTime, <D as Deserializer<'de>>::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<STRICTNESS> SerializeAs<SystemTime> for TimestampSecondsWithFrac<String, STRICTNESS>

where STRICTNESS: Strictness,

fn serialize_as<S>( source: &SystemTime, serializer: S, ) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl<STRICTNESS> SerializeAs<SystemTime> for TimestampSecondsWithFrac<f64, STRICTNESS>

where STRICTNESS: Strictness,

fn serialize_as<S>( source: &SystemTime, serializer: S, ) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.