examples/tutorial-read-serde-invalid-02.rs

use std::error::Error;
use std::io;
use std::process;

use serde::Deserialize;
#[derive(Debug, Deserialize)]
#[serde(rename_all = "PascalCase")]
struct Record {
    latitude: f64,
    longitude: f64,
    #[serde(deserialize_with = "csv::invalid_option")]
    population: Option<u64>,
    city: String,
    state: String,
}

fn run() -> Result<(), Box<dyn Error>> {
    let mut rdr = csv::Reader::from_reader(io::stdin());
    for result in rdr.deserialize() {
        let record: Record = result?;
        println!("{:?}", record);
    }
    Ok(())
}

fn main() {
    if let Err(err) = run() {
        println!("{}", err);
        process::exit(1);
    }
}