Module rusqlite::types

Expand description

Traits dealing with SQLite data types.

SQLite uses a dynamic type system. Implementations of the ToSql and FromSql traits are provided for the basic types that SQLite provides methods for:

Integers (i32 and i64; SQLite uses i64 internally, so getting an i32 will truncate if the value is too large or too small).
Reals (f64)
Strings (String and &str)
Blobs (Vec<u8> and &[u8])

Additionally, because it is such a common data type, implementations are provided for time::Timespec that use the RFC 3339 date/time format, "%Y-%m-%dT%H:%M:%S.%fZ", to store time values as strings. These values can be parsed by SQLite’s builtin datetime functions. If you want different storage for timespecs, you can use a newtype. For example, to store timespecs as f64s:

extern crate rusqlite;
extern crate time;

use rusqlite::types::{FromSql, FromSqlResult, ToSql, ToSqlOutput, ValueRef};
use rusqlite::Result;

pub struct TimespecSql(pub time::Timespec);

impl FromSql for TimespecSql {
    fn column_result(value: ValueRef) -> FromSqlResult<Self> {
        f64::column_result(value).map(|as_f64| {
            TimespecSql(time::Timespec {
                sec: as_f64.trunc() as i64,
                nsec: (as_f64.fract() * 1.0e9) as i32,
            })
        })
    }
}

impl ToSql for TimespecSql {
    fn to_sql(&self) -> Result<ToSqlOutput> {
        let TimespecSql(ts) = *self;
        let as_f64 = ts.sec as f64 + (ts.nsec as f64) / 1.0e9;
        Ok(as_f64.into())
    }
}

ToSql and FromSql are also implemented for Option<T> where T implements ToSql or FromSql for the cases where you want to know if a value was NULL (which gets translated to None).