Macro microdb::extract

macro_rules! extract {
    ($val:expr) => { ... };
}

Convenience macro to extract a value from the database and return Ok(None) if not found.

Example usage:

fn from_db<P: Path>(path: P, db: &MicroDB) -> Result<Option<Self>, std::io::Error> {
    Ok(Some(Self {
        username: extract!(db.get_raw(path.sub_path("username"))),
        email_address: extract!(db.get_raw(path.sub_path("email"))),
        password_hash: extract!(db.get_raw(path.sub_path("pass"))),
    }))
}